EXAR XRT75R03D

XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
DECEMBER 2003
REV. 1.0.2
GENERAL DESCRIPTION
TRANSMITTER:
The XRT75R03D is a three-channel fully integrated
Line Interface Unit (LIU) featuring EXAR’s R3
Technology (Reconfigurable, Relayless Redundancy)
with Jitter Attenuator for E3/DS3/STS-1 applications.
It
incorporates
3
independent
Receivers,
Transmitters and Jitter Attenuators in a single 128 pin
LQFP package.
Each channel of the XRT75R03D can be
independently configured to operate in the data rate,
E3 (34.368 MHz), DS3 (44.736 MHz) or STS-1 (51.84
MHz). Each transmitter can be turned off and tristated for redundancy support or for conserving
power.
The XRT75R03D’s differential receiver provides high
noise interference margin and is able to receive the
data over 1000 feet of cable or with up to 12 dB of
cable attenuation.
The XRT75R03D incorporates an advanced crystalless jitter attenuator per channel that can be selected
either in the transmit or receive path. The jitter
attenuator performance meets the ETSI TBR-24 and
Bellcore GR-499 specifications.
• R3
Technology
Redundancy)
(Reconfigurable,
• Compliant with Bellcore GR-499, GR-253 and ANSI
T1.102 Specification for transmit pulse
• Tri-state Transmit output capability for redundancy
applications
• Each Transmitter can be independently turned on
or off
• Transmitters provide Voltage Output Drive
JITTER ATTENUATOR:
• On chip advanced crystal-less Jitter Attenuator for
each channel
• Jitter Attenuator can be selected in Receive or
Transmit paths
• Meets ETSI TBR 24 Jitter Transfer Requirements
• Compliant with jitter transfer template outlined in
ITU G.751, G.752, G.755 and GR-499-CORE,1995
standards
• Jitter Attenuator can be disabled
The
XRT75R03D
provides
both
Serial
Microprocessor Interface as well as Hardware mode
for programming and control.
CONTROL AND DIAGNOSTICS:
The XRT75R03D supports local, remote and digital
loop-backs. The device also has a built-in Pseudo
Random Binary Sequence (PRBS) generator and
detector with the ability to insert and detect single bit
error for diagnostic purposes.
• Supports
FEATURES
Technology
Redundancy)
• 5 wire Serial Microprocessor Interface for control
and configuration
optional
internal
Transmit
(Reconfigurable,
Relayless
• On chip Clock and Data Recovery circuit for high
input jitter tolerance
• Meets E3/DS3/STS-1 Jitter Tolerance Requirement
• Detects and Clears LOS as per G.775
• Receiver Monitor mode handles up to 20 dB flat
loss with 6 dB cable attenuation
• On chip B3ZS/HDB3 encoder and decoder that can
be either enabled or disabled
• On-chip clock synthesizer provides the appropriate
rate clock from a single 12.288 MHz Clock
• Provides low jitter output clock
driver
monitoring
• Hardware Mode for control and configuration
• Each channel supports Local, Remote and Digital
Loop-backs
RECEIVER:
• R3
Relayless
• Single 3.3 V ± 5% power supply
• 5 V Tolerant I/O
• Available in 128 pin LQFP
• - 40°C to 85°C Industrial Temperature Range
APPLICATIONS
• E3/DS3 Access Equipment
• STS1-SPE to DS3 De-Synchronizing
• DSLAMs
• Digital Cross Connect Systems
• CSU/DSU Equipment
• Routers
• Fiber Optic Terminals
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
FIGURE 1. BLOCK DIAGRAM OF THE XRT 75R03D
SDI
SDO
INT
SClk
CS
RESET
HOST/HW
STS-1/DS3_(n)
E3_(n)
REQEN_(n)
RTIP_(n)
RRing_(n)
SR/DR
LLB_(n)
XRT75R03D
XRT75R03D
Serial
Processor
Interface
CLKOUT
E3Clk,DS3Clk,
STS-1Clk
RLOL_(n)
RxON
RxClkINV
Clock
Synthesizer
Peak Detector
AGC/
Equalizer
Clock & Data
Recovery
Slicer
Jitter
Attenuator
LOS
Detector
Local
LoopBack
MUX
Invert
RxClk_(n)
HDB3/
B3ZS
Decoder
RPOS_(n)
Remote
LoopBack
RNEG_(n)/
LCV_(n)
RLB_(n)
RLOS_(n)
LOSTHR
JATx/Rx
TTIP_(n)
TRing_(n)
MTIP_(n)
MRing_(n)
Line
Driver
Device
Monitor
Tx
Pulse
Shaping
Jitter
Attenuator
Timing
Control
MUX
HDB3/
B3ZS
Encoder
TPData_(n)
TNData_(n)
TxClk_(n)
TAOS_(n)
Tx
Control
DMO_(n)
TxLEV_(n)
Channel 0
TxON_(n)
Channel 1
Channel 2
Notes: 1. (n) = 0, 1 or 2 for respective Channels
2. Serial Processor Interface input pins are shared by the three Channels in "Host" Mode and redefined in the "Hardware" Mode.
TRANSMIT INTERFACE CHARACTERISTICS
• Accepts either Single-Rail or Dual-Rail data from Terminal Equipment and generates a bipolar signal to the
line
• Integrated Pulse Shaping Circuit
• Built-in B3ZS/HDB3 Encoder (which can be disabled)
• Accepts Transmit Clock with duty cycle of 30%-70%
• Generates pulses that comply with the ITU-T G.703 pulse template for E3 applications
• Generates pulses that comply with the DSX-3 pulse template, as specified in Bellcore GR-499 -CORE and
ANSI T1.102_1993
• Generates pulses that comply with the STSX-1 pulse template, as specified in Bellcore GR-253-CORE
• Transmitter can be turned off in order to support redundancy designs
RECEIVE INTERFACE CHARACTERISTICS
• Integrated Adaptive Receive Equalization (optional) for optimal Clock and Data Recovery
• Declares and Clears the LOS defect per ITU-T G.775 requirements for E3 and DS3 applications
• Meets Jitter Tolerance Requirements, as specified in ITU-T G.823_1993 for E3 Applications
• Meets Jitter Tolerance Requirements, as specified in Bellcore GR-499-CORE for DS3 Applications
• Declares Loss of Signal (LOS) and Loss of Lock (LOL) Alarms
• Built-in B3ZS/HDB3 Decoder (which can be disabled)
• Recovered Data can be muted while the LOS Condition is declared
• Outputs either Single-Rail or Dual-Rail data to the Terminal Equipment
2
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
TEST
RESET
AGND_2
LOSTHR
STS-1/DS3_1
LLB_1
RLB_1
REQEN_1
E3_1
RxAVDD_1
RRing_1
RTIP_1
RxAGND_1
RxAGND_2
RTIP_2
RRing_2
RxAVDD_2
E3_2
REQEN_2
RLB_2
LLB_2
STS-1/DS3_2
RxAGND_0
RTIP_0
RRing_0
RxAVDD_0
E3_0
REQEN_0
RLB_0
LLB_0
STS-1/DS3_0
LOSMUT/INT
HOST/HW
RxMON/SDO
RxON/SDI
TxClkINV/SClk
RxClkINV/CS
SR/DR
FIGURE 2. PIN OUT OF THE XRT75R03D
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
XRT75R03D
RLOL_2
RLOS_2
ICT
RLOL_0
RLOS_0
RxDGND_0
RPOS_0
RNEG_0/LCV_0
RxClk_0
RxDVDD_0
RxDVDD_2
RPOS_2
RNEG_2/LCV_2
RxClk_2
RxDGND_2
AGND_0
JAGND_2
JAGND_0
JAVDD_0
JAVDD_2
JA0
JATx/Rx
JA1
TxAGND_0
DMO_0
TxAVDD_0
TxON_1
TNData_1
TPData_1
TxClk_1
MRing_1
MTIP_1
TAOS_1
TAOS_2
TxLEV_1
TxLEV_2
TTIP_1
TxVDD_1
TRing_1
TxGND_1
TxAGND_2
MRing_2
MTIP_2
TxGND_2
TRing_2
TxVDD_2
TTIP_2
DMO_2
TxAVDD_2
TNData_2
TPData_2
TxClk_2
TxGND_0
TRing_0
TxVDD_0
TTIP_0
MTIP_0
MRing_0
TNData_0
TPData_0
TxClk_0
TxLEV_0
TAOS_0
TxON_0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RLOL_1
RLOS_1
EXDGND
SFM_EN
E3Clk/CLK_EN
DS3Clk/CLK_OUT
STS-1Clk/12M
EXDVDD
RxDVDD_1
RPOS_1
RNEG_1/LCV_1
RxClk_1
RxDGND_1
AGND_1
JADGND
JAGND_1
JADVDD
JAVDD_1
REFAVDD
RXA
RXB
REFGND
TxON_2
TxAGND_1
DMO_1
TxAVDD_1
ORDERING INFORMATION
PART NUMBER
PACKAGE
OPERATING TEMPERATURE RANGE
XRT75R03DIV
128 Pin LQFP
- 40°C to + 85°C
3
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE OF CONTENTS
GENERAL DESCRIPTION ................................................................................................. 1
FEATURES .................................................................................................................................................... 1
APPLICATIONS .............................................................................................................................................. 1
TRANSMIT INTERFACE CHARACTERISTICS ...................................................................................................... 2
RECEIVE INTERFACE CHARACTERISTICS ........................................................................................................ 2
Figure 1. Block Diagram of the XRT 75R03D ................................................................................................... 2
Figure 2. Pin Out of the XRT75R03D ............................................................................................................... 3
ORDERING INFORMATION ................................................................................................................... 3
TABLE OF CONTENTS .................................................................................................................................... I
PIN DESCRIPTIONS (BY FUNCTION) .............................................................................. 4
SYSTEM-SIDE TRANSMIT INPUT AND TRANSMIT CONTROL PINS ...................................................................... 4
TRANSMIT LINE SIDE PINS ............................................................................................................................ 8
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS .................................................................... 10
RECEIVE LINE SIDE PINS ............................................................................................................................ 17
GENERAL CONTROL PINS ........................................................................................................................... 18
CONTROL AND ALARM INTERFACE ............................................................................................................... 20
JITTER ATTENUATOR INTERFACE ................................................................................................................. 20
POWER SUPPLY AND GROUND PINS ............................................................................................................ 23
XRT75R03D PIN LISTING IN NUMERICAL ORDER ........................................................................................ 25
1.0 R3 Technology (reconfigurable, relayless redundancy) ............................................................... 30
1.1 NETWORK ARCHITECTURE ................................................................................................................................ 30
Figure 3. Network Redundancy Architecture ................................................................................................. 30
1.2 POWER FAILURE PROTECTION .......................................................................................................................... 30
1.3 SOFTWARE VS HARDWARE AUTOMATIC PROTECTION SWITCHING ...................................................................... 30
2.0 ELECTRICAL CHARACTERISTICS .................................................................................................
TABLE 1: ABSOLUTE MAXIMUM RATINGS ............................................................................................................
TABLE 2: DC ELECTRICAL CHARACTERISTICS: ...................................................................................................
3.0 TIMING CHARACTERISTICS ............................................................................................................
Figure 4. Typical interface between terminal equipment and the XRT75R03D (dual-rail data) ......................
Figure 5. Transmitter Terminal Input Timing ...................................................................................................
Figure 6. Receiver Data output and code violation timing ..............................................................................
Figure 7. Transmit Pulse Amplitude test circuit for E3, DS3 and STS-1 Rates ...............................................
4.0 LINE SIDE CHARACTERISTICS: .....................................................................................................
31
31
31
32
32
32
33
33
34
4.1 E3 LINE SIDE PARAMETERS: ............................................................................................................................. 34
Figure 8. Pulse Mask for E3 (34.368 mbits/s) interface as per itu-t G.703 .....................................................
TABLE 3: E3 TRANSMITTER LINE SIDE OUTPUT AND RECEIVER LINE SIDE INPUT SPECIFICATIONS ...........................
Figure 9. Bellcore GR-253 CORE Transmit Output Pulse Template for SONET STS-1 Applications ............
TABLE 4: STS-1 PULSE MASK EQUATIONS ........................................................................................................
TABLE 5: STS-1 TRANSMITTER LINE SIDE OUTPUT AND RECEIVER LINE SIDE INPUT SPECIFICATIONS (GR-253) .
Figure 10. Transmit Ouput Pulse Template for DS3 as per Bellcore GR-499 ................................................
TABLE 6: DS3 PULSE MASK EQUATIONS ...........................................................................................................
TABLE 7: DS3 TRANSMITTER LINE SIDE OUTPUT AND RECEIVER LINE SIDE INPUT SPECIFICATIONS (GR-499) .....
Figure 11. Microprocessor Serial Interface Structure ......................................................................................
Figure 12. Timing Diagram for the Microprocessor Serial Interface ................................................................
TABLE 8: MICROPROCESSOR SERIAL INTERFACE TIMINGS ( TA = 250C, VDD=3.3V± 5% AND LOAD = 10PF) .....
34
35
36
36
37
37
38
38
39
39
39
FUNCTIONAL DESCRIPTION: ........................................................................................ 41
5.0 The Transmitter Section: ................................................................................................................. 41
Figure 13. Single-Rail or NRZ Data Format (Encoder and Decoder are Enabled) ......................................... 41
Figure 14. Dual-Rail Data Format (encoder and decoder are disabled) ......................................................... 41
5.1 TRANSMIT CLOCK: ...........................................................................................................................................
5.2 B3ZS/HDB3 ENCODER: ..................................................................................................................................
5.2.1 B3ZS Encoding: .................................................................................................................................
5.2.2 HDB3 Encoding: .................................................................................................................................
I
42
42
42
42
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
Figure 15. B3ZS Encoding Format ................................................................................................................. 42
Figure 16. HDB3 Encoding Format ................................................................................................................ 42
5.3 TRANSMIT PULSE SHAPER: ..............................................................................................................................
5.3.1 Guidelines for using Transmit Build Out Circuit: ...........................................................................
5.3.2 Interfacing to the line: .......................................................................................................................
5.4 TRANSMIT DRIVE MONITOR: .............................................................................................................................
5.5 TRANSMITTER SECTION ON/OFF: ......................................................................................................................
43
43
43
44
44
6.0 The Receiver Section: ...................................................................................................................... 44
6.1 AGC/EQUALIZER: ............................................................................................................................................ 44
Figure 17. Transmit Driver Monitor set-up. ..................................................................................................... 44
6.1.1 Interference Tolerance: ..................................................................................................................... 45
Figure 18. Interference Margin Test Set up for DS3/STS-1 ........................................................................... 45
6.2 CLOCK AND DATA RECOVERY: ......................................................................................................................... 46
Figure 19. Interference Margin Test Set up for E3. ........................................................................................ 46
TABLE 9: INTERFERENCE MARGIN TEST RESULTS .............................................................................................. 46
6.3 B3ZS/HDB3 DECODER: .................................................................................................................................. 47
6.4 LOS (LOSS OF SIGNAL) DETECTOR: ................................................................................................................ 47
6.4.1 DS3/STS-1 LOS Condition: ................................................................................................................ 47
DISABLING ALOS/DLOS DETECTION: ......................................................................................................... 47
6.4.2 E3 LOS Condition: ............................................................................................................................. 47
TABLE 10: THE ALOS (ANALOG LOS) DECLARATION AND CLEARANCE THRESHOLDS FOR A GIVEN SETTING OF
LOSTHR AND REQEN (DS3 AND STS-1 APPLICATIONS) ................................................................... 47
Figure 20. Loss Of Signal Definition for E3 as per ITU-T G.775 .................................................................... 48
Figure 21. Loss of Signal Definition for E3 as per ITU-T G.775. .................................................................... 48
6.4.3 Muting the Recovered Data with LOS condition: ............................................................................ 49
7.0 Jitter: ................................................................................................................................................. 49
7.1 JITTER TOLERANCE - RECEIVER: ...................................................................................................................... 49
7.1.1 DS3/STS-1 Jitter Tolerance Requirements: ..................................................................................... 49
Figure 22. Jitter Tolerance Measurements ..................................................................................................... 49
7.1.2 E3 Jitter Tolerance Requirements: ................................................................................................... 50
Figure 23. Input Jitter Tolerance For DS3/STS-1 .......................................................................................... 50
Figure 24. Input Jitter Tolerance for E3 ......................................................................................................... 50
7.2 JITTER TRANSFER - RECEIVER/TRANSMITTER: .................................................................................................. 51
7.3 JITTER ATTENUATOR: ...................................................................................................................................... 51
TABLE 11: JITTER AMPLITUDE VERSUS MODULATION FREQUENCY (JITTER TOLERANCE) ..................................... 51
TABLE 12: JITTER TRANSFER SPECIFICATION/REFERENCES ............................................................................... 51
7.3.1 Jitter Generation: ............................................................................................................................... 52
8.0 Serial Host interface: ....................................................................................................................... 52
TABLE 13: JITTER TRANSFER PASS MASKS ....................................................................................................... 52
Figure 25. Jitter Transfer Requirements and Jitter Attenuator Performance .................................................. 52
TABLE 14: FUNCTIONS OF SHARED PINS ............................................................................................................ 53
TABLE 15: XRT75R03D REGISTER MAP - QUICK LOOK .................................................................................... 54
................................................................................................................................................................. 56
THE REGISTER MAP AND DESCRIPTION FOR THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU IC .
56
Legend: ..................................................................................................................................................................56
TABLE 16: COMMAND REGISTER ADDRESS MAP, WITHIN THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU W/ JITTER
ATTENUATOR IC ................................................................................................................................. 56
THE GLOBAL/CHIP-LEVEL REGISTERS ............................................................................................... 58
................................................................................................................................................................. 58
REGISTER DESCRIPTION - GLOBAL REGISTERS .............................................................................. 58
TABLE 17: LIST AND ADDRESS LOCATIONS OF GLOBAL REGISTERS .................................................................... 58
TABLE 18: APS/REDUNDANCY CONTROL REGISTER - CR0 (ADDRESS LOCATION = 0X00) .................................. 58
TABLE 19: BLOCK LEVEL INTERRUPT ENABLE REGISTER - CR32 (ADDRESS LOCATION = 0X20) ......................... 61
TABLE 20: BLOCK LEVEL INTERRUPT STATUS REGISTER - CR33 (ADDRESS LOCATION = 0X21) ......................... 62
TABLE 21: DEVICE/PART NUMBER REGISTER - CR62 (ADDRESS LOCATION = 0X3E) .......................................... 63
................................................................................................................................................................. 64
II
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
THE PER-CHANNEL REGISTERS .......................................................................................................... 64
TABLE 22: CHIP REVISION NUMBER REGISTER - CR63 (ADDRESS LOCATION = 0X3F) ........................................ 64
TABLE 23: COMMAND REGISTER ADDRESS MAP, WITHIN THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU W/ JITTER
ATTENUATOR IC ................................................................................................................................. 64
REGISTER DESCRIPTION - PER CHANNEL REGISTERS ................................................................... 66
TABLE 24: SOURCE LEVEL INTERRUPT ENABLE REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X01 .................. 66
TABLE 25: SOURCE LEVEL INTERRUPT STATUS REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X02 .................. 68
TABLE 26: ALARM STATUS REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X03 ................................................ 70
TABLE 27: TRANSMIT CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X04 ......................................... 75
TABLE 28: RECEIVE CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X05 ........................................... 78
TABLE 29: CHANNEL CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X06 ......................................... 80
TABLE 30: JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07 ......................... 83
9.0 Diagnostic Features: ........................................................................................................................ 85
9.1 PRBS GENERATOR AND DETECTOR: ................................................................................................................ 85
9.2 LOOPBACKS: ............................................................................................................................................... 85
9.2.1 ANALOG LOOPBACK: ....................................................................................................................... 85
Figure 26. PRBS MODE ................................................................................................................................. 85
Figure 27. Analog Loopback ........................................................................................................................... 86
9.2.2 DIGITAL LOOPBACK: ........................................................................................................................ 87
9.2.3 REMOTE LOOPBACK: ....................................................................................................................... 87
Figure 28. Digital Loopback ............................................................................................................................ 87
Figure 29. Remote Loopback .......................................................................................................................... 87
9.3 TRANSMIT ALL ONES (TAOS): ................................................................................................................... 88
10.0 THE SONET/SDH DE-SYNC FUNCTION WITHIN THE XRT75R03D ............................................ 88
Figure 30. Transmit All Ones (TAOS) ............................................................................................................. 88
10.1 BACKGROUND AND DETAILED INFORMATION - SONET DE-SYNC APPLICATIONS ........................ 89
Figure 31. A Simple Illustration of a DS3 signal being mapped into and transported over the SONET Network
90
10.2 MAPPING/DE-MAPPING JITTER/WANDER .............................................................................................. 91
10.2.1 HOW DS3 DATA IS MAPPED INTO SONET .................................................................................... 91
Figure 32. A Simple Illustration of the SONET STS-1 Frame ......................................................................... 92
Figure 33. A Simple Illustration of the STS-1 Frame Structure with the TOH and the Envelope Capacity Bytes
Designated .................................................................................................................................... 93
Figure 34. The Byte-Format of the TOH within an STS-1 Frame .................................................................... 94
Figure 35. The Byte-Format of the TOH within an STS-1 Frame .................................................................... 95
Figure 36. Illustration of the Byte Structure of the STS-1 SPE ....................................................................... 96
Figure 37. An Illustration of Telcordia GR-253-CORE’s Recommendation on how map DS3 data into an STS-1
SPE ............................................................................................................................................... 97
Figure 38. A Simplified "Bit-Oriented" Version of Telcordia GR-253-CORE’s Recommendation on how to map
DS3 data into an STS-1 SPE ........................................................................................................ 97
10.2.2 DS3 Frequency Offsets and the Use of the "Stuff Opportunity" Bits .......................................... 98
Figure 39. A Simple Illustration of a DS3 Data-Stream being Mapped into an STS-1 SPE, via a PTE .......... 99
Figure 40. An Illustration of the STS-1 SPE traffic that will be generated by the "Source" PTE, when mapping in
a DS3 signal that has a bit rate of 44.736Mbps + 1ppm, into an STS-1 signal .......................... 100
10.3 JITTER/WANDER DUE TO POINTER ADJUSTMENTS ........................................................................................ 102
10.3.1 The Concept of an STS-1 SPE Pointer ......................................................................................... 102
Figure 41. An Illustration of the STS-1 SPE traffic that will be generated by the Source PTE, when mapping a
DS3 signal that has a bit rate of 44.736Mbps - 1ppm, into an STS-1 signal .............................. 102
Figure 42. An Illustration of an STS-1 SPE straddling across two consecutive STS-1 frames ..................... 103
10.3.2 Pointer Adjustments within the SONET Network ........................................................................ 104
Figure 43. The Bit-format of the 16-Bit Word (consisting of the H1 and H2 bytes) with the 10 bits, reflecting the
location of the J1 byte, designated ............................................................................................. 104
Figure 44. The Relationship between the Contents of the "Pointer Bits" (e.g., the 10-bit expression within the H1
and H2 bytes) and the Location of the J1 Byte within the Envelope Capacity of an STS-1 Frame ...
104
10.3.3 Causes of Pointer Adjustments .................................................................................................... 105
III
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
Figure 45. An Illustration of an STS-1 signal being processed via a Slip Buffer .......................................... 106
Figure 46. An Illustration of the Bit Format within the 16-bit word (consisting of the H1 and H2 bytes) with the "I"
bits designated ........................................................................................................................... 107
Figure 47. An Illustration of the Bit-Format within the 16-bit word (consisting of the H1 and H2 bytes) with the
"D" bits designated ..................................................................................................................... 108
10.3.4 Why are we talking about Pointer Adjustments? ........................................................................ 109
10.4 CLOCK GAPPING JITTER .............................................................................................................................. 109
Figure 48. Illustration of the Typical Applications for the XRT75R03D in a SONET De-Sync Application ... 109
10.5 A REVIEW OF THE CATEGORY I INTRINSIC JITTER REQUIREMENTS (PER TELCORDIA GR-253-CORE) FOR DS3 AP........................................................................................................................................................................ 110
PLICATIONS
TABLE 31: SUMMARY OF "CATEGORY I INTRINSIC JITTER REQUIREMENT PER TELCORDIA GR-253-CORE, FOR DS3
APPLICATIONS .................................................................................................................................. 110
10.5.1 DS3 De-Mapping Jitter ................................................................................................................... 111
10.5.2 Single Pointer Adjustment ............................................................................................................ 111
Figure 49. Illustration of Single Pointer Adjustment Scenario ...................................................................... 111
10.5.3 Pointer Burst .................................................................................................................................. 112
10.5.4 Phase Transients ........................................................................................................................... 112
Figure 50. Illustration of Burst of Pointer Adjustment Scenario .................................................................... 112
Figure 51. Illustration of "Phase-Transient" Pointer Adjustment Scenario ................................................... 112
10.5.5 87-3 Pattern .................................................................................................................................... 113
10.5.6 87-3 Add .......................................................................................................................................... 113
Figure 52. An Illustration of the 87-3 Continuous Pointer Adjustment Pattern ............................................. 113
10.5.7 87-3 Cancel ..................................................................................................................................... 114
Figure 53. Illustration of the 87-3 Add Pointer Adjustment Pattern .............................................................. 114
Figure 54. Illustration of 87-3 Cancel Pointer Adjustment Scenario ............................................................. 114
10.5.8 Continuous Pattern ........................................................................................................................ 115
10.5.9 Continuous Add ............................................................................................................................ 115
Figure 55. Illustration of Continuous Periodic Pointer Adjustment Scenario ............................................... 115
10.5.10 Continuous Cancel ...................................................................................................................... 116
Figure 56. Illustration of Continuous-Add Pointer Adjustment Scenario ....................................................... 116
Figure 57. Illustration of Continuous-Cancel Pointer Adjustment Scenario .................................................. 116
10.6 A REVIEW OF THE DS3 WANDER REQUIREMENTS PER ANSI T1.105.03B-1997. ........................................... 117
10.7 A REVIEW OF THE INTRINSIC JITTER AND WANDER CAPABILITIES OF THE XRT75R03D IN A TYPICAL SYSTEM APPLICATION .......................................................................................................................................................................... 117
10.7.1 Intrinsic Jitter Test results ............................................................................................................ 117
TABLE 32: SUMMARY OF "CATEGORY I INTRINSIC JITTER TEST RESULTS" FOR SONET/DS3 APPLICATIONS ..... 117
10.7.2 Wander Measurement Test Results ............................................................................................. 118
10.8 DESIGNING WITH THE XRT75R03D .............................................................................................................. 118
10.8.1 How to design and configure the XRT75R03D to permit a system to meet the above-mentioned
Intrinsic Jitter and Wander requirements ..................................................................................................................... 118
Figure 58. Illustration of the XRT75R03D being connected to a Mapper IC for SONET De-Sync Applications ..
118
CHANNEL CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X06 ................................................. 119
CHANNEL 1 ADDRESS LOCATION = 0X0E ......................................... 119
CHANNEL 2 ADDRESS LOCATION = 0X16 ......................................... 119
CHANNEL CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X06 ................................................. 120
CHANNEL 1 ADDRESS LOCATION = 0X0E .............................................. 120
CHANNEL 2 ADDRESS LOCATION = 0X16 ............................................... 120
JITTER ATTENUATOR CONTROL REGISTER - (CHANNEL 0 ADDRESS LOCATION = 0X07 ............................... 120
CHANNEL 1 ADDRESS LOCATION = 0X0F .................................. 120
CHANNEL 2 ADDRESS LOCATION = 0X17 .................................. 120
10.8.2 Recommendations on Pre-Processing the Gapped Clocks (from the Mapper/ASIC Device) prior
to routing this DS3 Clock and Data-Signals to the Transmit Inputs of the XRT75R03D .......................................... 121
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07 ................................
CHANNEL 1 ADDRESS LOCATION = 0X0F ............................
CHANNEL 2 ADDRESS LOCATION = 0X17 ............................
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07 ................................
IV
121
121
121
121
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
CHANNEL 1 ADDRESS LOCATION = 0X0F ............................
CHANNEL 2 ADDRESS LOCATION = 0X17 ............................
Figure 59. Illustration of MINOR PATTERN P1 ............................................................................................
Figure 60. Illustration of MINOR PATTERN P2 ............................................................................................
Figure 61. Illustration of Procedure which is used to Synthesize MAJOR PATTERN A ...............................
Figure 62. Illustration of MINOR PATTERN P3 ............................................................................................
Figure 63. Illustration of Procedure which is used to Synthesize PATTERN B ............................................
121
121
122
123
123
124
124
10.8.3 How does the XRT75R03D permit the user to comply with the SONET APS Recovery Time requirements of 50ms (per Telcordia GR-253-CORE)? ................................................................................................... 125
Figure 64. Illustration of the SUPER PATTERN which is output via the "OC-N to DS3" Mapper IC ............ 125
Figure 65. Simple Illustration of the XRT75R03D being used in a SONET De-Synchronizer" Application ... 125
TABLE 33: MEASURED APS RECOVERY TIME AS A FUNCTION OF DS3 PPM OFFSET .......................................... 126
10.8.4 How should one configure the XRT75R03D, if one needs to support "Daisy-Chain" Testing at the
end Customer’s site? ..................................................................................................................................................... 127
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07 ................................. 127
CHANNEL 1 ADDRESS LOCATION = 0X0F ............................ 127
CHANNEL 2 ADDRESS LOCATION = 0X17 ............................ 127
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07 ................................. 127
CHANNEL 1 ADDRESS LOCATION = 0X0F ................................... 127
CHANNEL 2 ADDRESS LOCATION = 0X17 ................................... 127
ORDERING INFORMATION ............................................................................................................... 128
PACKAGE DIMENSIONS - 14X20 MM, 128 PIN PACKAGE .............................................................................. 128
REVISIONS ............................................................................................................................................... 129
V
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
PIN DESCRIPTIONS (BY FUNCTION)
SYSTEM-SIDE TRANSMIT INPUT AND TRANSMIT CONTROL PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
38
TxON_0
I
1
TxON_1
Transmitter ON Input - Channel 1:
125
TxON_2
Transmitter ON Input - Channel 2:
Transmitter ON Input - Channel 0:
These input pins are used to either enable or disable the Transmit Output
Driver corresponding to Channel_n.
"Low" - Disables the Transmit Output Driver of the corresponding Channel.
In this setting, the corresponding TTIP_n and TRING_n output pins will be
tri-stated.
"High" - Enables the Transmit Output Driver of the corresponding Channel.
In this setting, the corresponding TTIP_n and TRING_n output pins will be
enabled.
NOTES:
1. Even when the XRT75R03D is configured in HOST mode, these
pins will be active. To enable software control of the Transmit
Output Driver outputs, pull these pins "High".
2. When Transmitters are turned off either in Host or Hardware
mode, the TTIP and TRing outputs are Tri-stated.
3. These pins are internally pulled "High"
35
TxClk_0
I
4
TxClk_1
Transmit Clock Input f - Channel 1:
26
TxClk_2
Transmit Clock Input - Channel 2:
Transmit Clock Input - Channel 0:
These input pins have two functions:
• They function as the timing source for the Transmit Section of the
corresponding channel within the XRT75R03D.
• They also are used by the Transmit Section of the LIU IC to sample the
corresponding TPDATA_n and TNDATA_n input pin.
NOTE: The user is expected to supply a 44.736MHz ± 20ppm clock signal
(for DS3 applications), 34.368MHz ± 20 ppm clock signal (for E3
applications) or a 51.84MHz ± 4.6ppm clock signal (for STS-1,
Stratum 3E or better applications).
4
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
SYSTEM-SIDE TRANSMIT INPUT AND TRANSMIT CONTROL PINS
PIN #
SIGNAL NAME
TYPE
34
TPDATA_0/TxDATA_0
I
3
TPDATA_1/TxDATA_1
25
TPDATA_2/TxDATA_2
DESCRIPTION
Transmit Positive Data Input - Channel 0:
Transmit Positive Data Input - Channel 1:
Transmit Positive Data Input - Channel 2:
Transmit Positive Data/Data Input - Channel n:
The function of these input pins depends upon whether the corresponding
channel has been configured to operate in the Single-Rail or Dual-Rail
Mode.
Single Rail Mode - Transmit Data Input - Channel n:
If the Channel has been configured to operate in the Single-Rail Mode, then
all transmit output data will be serially applied to this input pin. This signal
will latched into the Transmit Section circuitry upon either the rising or falling edge of the TxCLK_n signal, depending upon user configuration.
In the Single-Rail Mode, the Transmit Section of the LIU IC will then encode
this data into either the B3ZS line code (for DS3 and STS-1 applications) or
the HDB3 line code (for E3 applications).
Dual Rail Mode - Transmit Positive Data Input - Channel n:
If the Channel has been configured to operate in the Dual-Rail Mode, then
the user should apply a pulse to this input pin, anytime the Transmit Section
of the LIU IC is suppose to generate and transmit a positive-polarity pulse
onto the line. This signal will be latched into the Transmit Section circuitry
upon either the rising or falling edge of the TxCLK_n signal, depending
upon user configuration.
In the Dual-Rail Mode, the Transmit Section of the LIU IC will NOT encode
this data into either the B3ZS or HDB3 line codes. If the user configures
the LIU IC to operate in the Dual-Rail Mode, then B3ZS/HDB3 encoding
must have already been done prior to providing the transmit output data to
this input pin.
33
TNData_0
2
TNData_1
I
Transmit Negative Data Input - Channel 1:
24
TNData_2
Transmit Negative Data Input - Channel 2:
Transmit Negative Data Input - Channel 0:
If a Channel has been configured to operate in the Dual-Rail Mode, then
the user should apply a pulse to this input pin anytime the Transmit Section
of the LIU IC is suppose to generate and transmit a negative-polarity pulse
onto the line. This signal will be latched into the Transmit Section circuitry
upon either the rising or falling edge of the TxCLK_n signal, depending
upon user configuration.
NOTE: If the Channel has been configured operate in the Single-Rail Mode,
then this input pin has no function, and should be tied to GND.
5
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
SYSTEM-SIDE TRANSMIT INPUT AND TRANSMIT CONTROL PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
37
TAOS_0
I
7
TAOS_1
Transmit "All Ones" Input - Channel 1:
8
TAOS_2
Transmit "All Ones" Input - Channel 2:
Transmit "All Ones" Input - Channel 0:
These input pin are used to configure the Transmit Section of the corresponding channel to generate and transmit an unframed "All Ones" pattern
via the DS3, E3 or STS-1 line signal to the remote terminal equipment.
When this configuration is implemented the Transmit Section will ignore the
data that it is accepting from the System-side equipment and will overwrite
this data will the "All Ones" Pattern.
"Low" - Does not configure the channel to transmit an unframed "All Ones"
Pattern to the remote terminal equipment. In this mode, the Transmit Section of the Channel will output data based upon the signals that are applied
to the TxPOS_n and TxNEG_n input pins.
"High" - Configures the Channel to transmit an unframed "All Ones" Pattern
to the remote terminal equipment. In this mode, the Transmit Section will
override the data that is applied to the TxPOS_n and TxNEG_n input pins,
and will proceed to generate and transmit an unframed "All Ones" pattern.
4. This input pin is ignored if the XRT75R03D is operating in the
HOST Mode and should be tied to GND.
5. These input pins are internally pulled down.
36
TxLEV_0
9
TxLEV_1
I
Transmit Line Build-Out Enable/Disable Select - Channel 0:
Transmit Line Build-Out Enable/Disable Select - Channel 1:
10
TxLEV_2
Transmit Line Build-Out Enable/Disable Select - Channel 2:
These input pins are used to enable or disable the Transmit Line Build-Out
(e.g., pulse-shaping) circuit within the corresponding channel. The user
should set these input pins either "High" or "Low" based upon the following
guidelines.
"Low" - If the cable length between the Transmit Output of the corresponding Channel and the DSX-3/STSX-1 location is 225 feet or less.
"High" - If the cable length between the Transmit Output of the corresponding Channel and the DSX-3/STSX-1 location is 225 feet or more.
NOTES:
1. These guidelines must be followed in order to insure that the
Transmit Section of Channel_n will always generate a DS3 pulse
that complies with the Isolated Pulse Template requirements per
Bellcore GR-499-CORE, or an STS-1 pulse that complies with the
Pulse Template requirements per Telcordia GR-253-CORE.
2. This input pin is inactive if the XRT75R03D has been configured
to operate in the Host Mode, or if the corresponding channel has
been configured to operate in the E3 Mode. If either of these
cases are true, then tie this input pin to GND.
3. These input pins are internally pulled "Low".
6
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
SYSTEM-SIDE TRANSMIT INPUT AND TRANSMIT CONTROL PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
40
DMO_0
O
127
DMO_1
Drive Monitor Output - Channel 1:
22
DMO_2
Drive Monitor Output - Channel 2:
Drive Monitor Output - Channel 0:
These output signals are used to indicate some sort of fault condition within
the Transmit Output signal path.
This output pin will toggle "High" anytime the Transmit Drive Monitor circuitry either, via the corresponding MTIP and MRING input pins or internally, detects no bipolar pulses via the Transmit Output line signal (e.g., via
the TTIP_n and TRING_n output pins) for 128 bit-periods.
This output pin will be driven "Low" anytime the Transmit Drive Monitor circuitry has detected at least one bipolar pulse via the Transmit Output line
signal within the last 128 bit periods.
67
TxClkINV/
SClk
I
Hardware Mode: Transmit Clock Invert
Host Mode: Serial Clock Input:
Hardware mode
This input pin is used to select the edge of the TxCLK_n input that the
Transmit Section of all channels will use to sample the TPDATA_n and
TNDATA_n input pins.
Setting this input pin “High” configures all three Transmitters to sample the
TPData_n and TNData_n data on the rising edge of the TxClk_n .
Setting this input pin “Low” configures all three Transmitters to sample the
TPData_n and TNData_n data on the falling edge of the TxClk_n .
Host Mode
In the Host Mode this pin functions as SClk input pin please refer to the pin
descriptions for the Microprocessor interface.
7
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TRANSMIT LINE SIDE PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
30
TTIP_0
O
11
TTIP_1
Transmit TTIP Output - Positive Polarity Signal - Channel 1:
21
TTIP_2
Transmit TTIP Output - Positive Polarity Signal - Channel 2:
Transmit TTIP Output - Positive Polarity Signal - Channel 0:
These output pins along with the corresponding TRING_n output pins, function
as the Transmit DS3/E3/STS-1 Line output signal drivers for a given channel, of
the XRT75R03D.
Connect this signal and the corresponding TRING_n output signal to a 1:1
transformer.
Whenever the Transmit Section of the Channel generates and transmits a positive-polarity pulse onto the line, this output pin will be pulsed to a "higher-voltage" than its corresponding TRING_n output pins.
Conversely, whenever the Transmit Section of the Channel generates and transmit a negative-polarity pulse onto the line, this output pin will be pulsed to a
"lower-voltage" than its corresponding TRING_n output pin.
NOTE: This output pin will be tri-stated whenever the corresponding TxON_n
input pin or bit-field is set to "0".
O
Transmit Ring Output - Negative Polarity Signal - Channel 0:
28
TRing_0
13
TRing_1
Transmit Ring Output - Negative Polarity Signal - Channel 1:
19
TRing_2
Transmit Ring Output - Negative Polarity Signal - Channel 2:
These output pins along with the corresponding TTIP_n output pins, function as
the Transmit DS3/E3/STS-1 Line output signal drivers for a given channel,
within the XRT75R03D.
Connect this signal and the corresponding TTIP_n output signal to a 1:1 transformer.
Whenever the Transmit Section of the Channel generates and transmits a positive-polarity pulse onto the line. This output pin will be pulsed to a "lower-voltage" than its corresponding TTIP_n output pins.
Conversely, whenever the Transmit Section of the Channel generates and transmit a negative-polarity pulse onto the line. This output pin will be pulsed to a
"higher-voltage" than its corresponding TTIP_n output pin.
NOTE: This output pin will be tri-stated whenever the corresponding TxON_n
input pin or bit-field is set to "0".
8
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TRANSMIT LINE SIDE PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
31
MTIP_0
I
6
MTIP_1
Monitor Tip Input - Positive Polarity Signal - Channel 1:
17
MTIP_2
Monitor Tip Input - Positive Polarity Signal - Channel 2:
Monitor Tip Input - Positive Polarity Signal - Channel 0:
These input pins along with MRING_n function as the Transmit Drive Monitor
Output (DMO) input monitoring pins. To (1) monitor the Transmit Output line
signal and (2) to perform this monitoring externally, then this pin MUST be connected to the corresponding TTIP_n output pin via a 274 ohm series resistor.
Similarly, the MRING_n input pin MUST also be connected to its corresponding
TRING_n output pin via a 274 ohm series resistor.
The MTIP_n and MRING_n input pins will continuously monitor the Transmit
Output line signal via the TTIP_n and TRING_n output pins for bipolar activity. If
these pins do not detect any bipolar activity for 128 bit periods, then the Transmit Drive Monitor circuit will drive the corresponding DMO_n output pin "High" in
order to denote a possible fault condition in the Transmit Output Line signal
path.
NOTES:
1. These input pins are inactive if the user choose to internally monitor
the Transmit Output line signal.
2. Internal Monitoring is only available as an option if the XRT75R03D in
is being operated in the Host Mode.
32
MRing_0
I
5
MRing_1
Monitor Ring Input - Channel 1:
16
MRing_2
Monitor Ring Input - Channel 2:
Monitor Ring Input - Channel 0:
These input pins along with MTIP_n function as the Transmit Drive Monitor Output (DMO) input monitoring pins. To (1) monitor the Transmit Output line signal
and (2) to perform this monitoring externally, then this input pin MUST be connected to the corresponding TRING_n output pin via a 274 ohm series resistor.
Similarly, the MTIP_n input pin MUST be connected to its corresponding
TTIP_n output pin via a 274 ohm series resistor.
The MTIP_n and MRING_n input pins will continuously monitor the Transmit
Output line signal via the TTIP_n and TRING_n output pins for bipolar activity. If
these pins do not detect any bipolar activity for 128 bit periods, then the Transmit Drive Monitor circuit will drive the corresponding DMO_n output pin "High" to
indicate a possible fault condition in the Transmit Output Line signal path.
NOTES:
1. These input pins are inactive if the user chooses to internally monitor
the Transmit Output line signal.
2. Internal Monitoring is only available as an option if the XRT75R03D is
being operated in the Host Mode.
9
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
60
RLOS_0
O
104
RLOS_1
Receive Loss of Signal Output Indicator - Channel 1:
63
RLOS_2
Receive Loss of Signal Output Indicator - Channel 2:
Receive Loss of Signal Output Indicator - Channel 0:
This output pin indicates whether or not the corresponding channel is declaring
the Loss of Signal (LOS) Defect condition.
"Low" - Indicates that the corresponding Channel is NOT currently declaring the
LOS defect condition.
"High" - Indicates that the corresponding Channel is currently declaring the LOS
defect condition.
61
RLOL_0
O
103
RLOL_1
Receive Loss of Lock Output Indicator - Channel 1:
64
RLOL_2
Receive Loss of Lock Output Indicator - Channel 2:
Receive Loss of Lock Output Indicator - Channel 0:
This output pin indicates whether or not the corresponding channel is declaring
the Loss of Lock (LOL) Condition.
"Low" - Indicates that the corresponding Channel is NOT declaring the LOL condition.
"High" - Indicates that the corresponding Channel is currently declaring the LOL
condition.
NOTE: The Receive Section of a given channel will declare the LOL condition
anytime the frequency of the Recovered Clock (RCLK) signal differs
from that of the E3CLK input clock signal (if the channel is operating in
the E3 Mode), the DS3CLK input clock signal (if the channel is
operating in the DS3 Mode) the STS-1CLK input clock signal (if the
channel is operating in the STS-1 Mode), or that clock signal which is
derived from the SFM Clock Synthesizer block (if the chip is operating in
the Single-Frequency Mode) by 0.5% (or 5000ppm) or more.
58
RPOS_0/RDATA_0
O
112
RPOS_1/RDATA_1
Receive Positive Data Output - Receive Data Output - Channel 1:
53
RPOS_2/RDATA_2
Receive Positive Data Output - Receive Data Output - Channel 2:
Receive Positive Data Output - Receive Data Output - Channel 0:
The function of these output pins depends upon whether the channel/device
has been configured to operate in the Single-Rail or Dual-Rail Mode.
Dual-Rail Mode - Receive Positive Polarity Data Output
If the channel/device has been configured to operate in the Dual-Rail Mode,
then all positive-polarity data will be output via this output pin. The negativepolarity data will be output via the corresponding RNEG_n output pin. In other
words, the Receive Section of the corresponding Channel will pulse this output
pin "High" for one period of RCLK_n anytime it receives a positive-polarity pulse
via the RTIP/RRING input pins.
The data that is output via this pin is updated upon a user-selectable edge of the
RCLK_n output clock signal.
Single-Rail Mode - Receive Data Output
If the channel/device has been configured to operate in the Single-Rail Mode,
then all Receive (or Recovered) data will be output via this output pin.
The data that is output via this pin is updated upon a user-selectable edge of the
RCLK_n output clock signal.
10
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
57
RNEG_0/LCV_0
O
Receive Negative Data Output/Line Code Violation Indicator Channel 0:
113
RNEG_1/LCV_1
Receive Negative Data Output/Line Code Violation Indicator Channel 1:
52
RNEG_2/LCV_2
Receive Negative Data Output/Line Code Violation Indicator Channel 2:
The function of these pins depends on whether the XRT75R03D is configured in
Single Rail or Dual Rail mode.
Dual-Rail Mode - Receive Negative Polarity Data Output
If the channel/device has been configured to operate in the Dual-Rail Mode,
then all negative-polarity data will be output via this output pin. The positivepolarity data will be output via the corresponding RPOS_n output pin. In other
words, the Receive Section of the corresponding Channel will pulse this output
pin "High" for one period of RCLK_n anytime it receives a negative-polarity
pulse via the RTIP/RRING input pins.
The data that is output via this pin is updated upon a user-selectable edge of the
RCLK_n output clock signal.
Single-Rail Mode - Line Code Violation Indicator Output
If the channel/device has been configured to operate in the Single-Rail Mode,
then this particular output pin will function as the Line Code Violation indicator
output.
In this configuration, the Receive Section of the Channel will pulse this output
pin "High" for at least one RCLK period whenever it detects either an LCV (Line
Code Violation) or an EXZ (Excessive Zero Event).
The data that is output via this pin is updated upon a user-selectable edge of the
RCLK_n output clock signal.
O
Receive Clock Output - Channel 0:
56
RxClk_0
114
RxClk_1
Receive Clock Output - Channel 1:
51
RxClk_2
Receive Clock Output - Channel 2:
This output pin functions as the Receive or recovered clock signal. All Receive
(or recovered) data will output via the RPOS_n and RNEG_n outputs upon the
user-selectable edge of this clock signal.
Additionally, if the device/channel has been configured to operate in the SingleRail Mode, then the RNEG_n/LCV_n output pins will also be updated upon the
user-selectable edge of this clock signal.
75
REQEN_0
I
Receive Equalization Enable Input - Channel 0:
95
REQEN_1
Receive Equalization Enable Input - Channel 1:
84
REQEN_2
Receive Equalization Enable Input - Channel 2:
These input pins are used to either enable or disable the Receive Equalizer
block within the Receive Section of the corresponding channel.
"Low" - Disables the Receive Equalizer within the corresponding channel.
"High" - Enables the Receive Equalizer within the corresponding channel.
NOTES:
1. For virtually all applications, it is recommend that this input pin be
pulled "High" and enable the Receive Equalizer.
2. This input pin ignored and should be tied to GND if the XRT75R03D
has been configured to operate in the Host Mode.
3. These input pins are internally pulled low.
11
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS
PIN #
SIGNAL NAME
TYPE
71
LOSMUT/
I/O
INT
DESCRIPTION
Muting Upon LOS Enable/Interrupt Output Pin
This input pin is used to configure the Receive Section, in each of the three
channels within the chip, to automatically pull their corresponding Recovered
Data Output pins (e.g. RPOS_n and RNEG_n) to GND anytime and for the
duration that the Receive Section declares the LOS defect condition. In other
words, this feature if enabled will cause the Receive Channel to automatically
mute the Recovered data anytime and for the duration that the Receive Section
declares the LOS defect condition.
"Low" - Disables the Muting upon LOS feature. In this setting the Receive Section will NOT automatically mute the Recovered Data whenever it is declaring
the LOS defect condition.
"High" - Enables the Muting upon LOS feature. In this setting the Receive Section will automatically mute the Recovered Data whenever it is declaring the
LOS defect condition.
NOTES:
1. This input pin is will function as the Interrupt Request output pin within
the Microprocessor Serial Interface, if the XRT75R03D has been
configured to operate in the Host Mode.
2. This configuration setting applies globally to each of the three (3)
channels within the XRT75R03D.
99
LOSTHR
I
Analog LOS Detector Threshold Level Select Input:
This input pin permits the user to select both of the following parameters for the
Analog LOS Detector within each of the three Receive Sections within the
XRT75R03D.
1. The Analog LOS Defect Declaration Threshold (e.g., the maximum signal
level that the Receive Section of a given channel must detect before
declaring the LOS Defect condition), and
2. The Analog LOS Defect Clearance Threshold (e.g., the minimum signal
level that the Receive Section of a given channel must detect before
clearing the LOS Defect condition)
Setting this input pin "High" selects one set of Analog LOS Defect Declaration
and Clearance thresholds. Setting this input pin "Low" selects the other set of
Analog LOS Defect Declaration and Clearance thresholds.
Please see Table 10 for more details.
NOTE:
This input pin is only active if at least one channel within the
XRT75R03D has been configured to operate in the DS3 or STS-1
Modes.
12
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS
PIN #
SIGNAL NAME
TYPE
69
RxMON/
I
SDO
DESCRIPTION
Receiver Monitor Mode Enable:
This input pin permits the user to configure each of the three (3) Receive Sections within the XRT75R03D, into the Receiver Monitor Mode.
If the user configures each of the Receive Sections into the Receive Monitor
Mode, then each of the Receiver Sections will be able to receive a nominal
DSX-3/STSX-1 signal that has been attenuated by 20dB of flat loss along with
6dB of cable loss, in an error-free manner, and without declaring the LOS defect
condition.
"Low" - Configures each of the Receive Sections to operate in the Normal
Mode.
"High" - Configures each of the Receive Sections to operate in the Receive
Monitor Mode.
NOTES:
1. This input pin will function as the SDO (Serial Data Output pin within
the Microprocessor Serial Interface) whenever the XRT75R03D has
been configured to operate in the Host Mode.
2. This configuration setting applies globally to all three (3) of the
channels within the XRT75R03D.
68
RxON/
SDI
I
Receive ON:
This input pin permits the user to either turn on or turn off each of the three (3)
Receive Sections within the XRT75R03D. If the user turns on the Receive Sections of each channel, then all three channels will begin to receive the incoming
DS3, E3 or STS-1 data-streams via the RTIP_n and RRING_n input pins.
Conversely, if the user turns off the Receive Section, then the entire Receive
Section (e.g., the AGC and Receive Equalizer blocks, Clock Recovery PLL, etc.)
will be powered down.
"Low" - Shuts off the Receive Sections within each of the three (3) Channels in
the XRT75R03D.
"High" - Turns on the Receive Sections within each of the three (3) Channels in
the XRT75R03D.
NOTES:
1. This input pin will function as the SDI (Serial Data Input pin within the
Microprocessor Serial Interface) whenever the XRT75R03D has been
configured to operate in the Host Mode.
2. This configuration setting applies globally to all three (3) of the
channels within the XRT75R03D.
3. This pin is internally pulled low.
13
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS
PIN #
SIGNAL NAME
TYPE
66
RxClkINV/
I
CS
DESCRIPTION
Receive Clock Invert Input - Chip Selectl:
In Hardware Mode is pin is used to configure the Receive Sections of the three
(3) channels in the XRT75R03D to either output the recovered data via the
RPOS_n or RNEG_n/LCV_n output pins upon either the rising or falling edge of
the RCLK_n clock output signal.
"Low" - Configures each of the Receive Sections to output the recovered data
via the RPOS_n and RNEG_n/LCV_n output pins upon the rising edge of the
RCLK_n output clock signal.
"High" - Configures each of the Receive Sections to output the recovered data
via the RPOS_n and RNEG_n/LCV_n output pins upon the falling edge of the
RCLK_n output clock signal.
NOTES:
1. This input pin will function as the CS (Chip Select Input pin) of the
Microprocessor Serial Interface when the XRT75R03D has been
configured to operate in the Host Mode.
2. This configuration setting applies globally to all three (3) of the
channels within the XRT75R03D.
3. If the Receive Sections are configured to operate in the Single-Rail
Mode, then the LCV_n output pin will be updated on the user-selected
edge of the RCLK_n signal, per this configuration selection.
106
SFM_EN
I
Single Frequency Mode Enable:
This input pin is used to configure the XRT75R03D to operate in the SFM (Single Frequency) Mode.
When this feature is invoked the Single-Frequency Mode Synthesizer will
become active. By applying a 12.288MHz clock signal to pin 109, STS-1CLK/
12M the XRT75R03D will, depending upon which mode the user has configured
each of the three channels, generate all of the appropriate clock signals (e.g.,
34.368MHz, 44.736MHz or 51.84. Further, the XRT75R03D internal circuitry
will route each of these synthesized clock signals to the appropriate nodes of
the corresponding three channels in the XRT75R03D.
"Low" - Disables the Single Frequency Mode. In this configuration setting, the
user is required to supply to the E3CLK, DS3CLK or STS-1CLK input pins all of
the relevant clock signals that are to be used within the chip.
"High" - Enables the Single-Frequency Mode. A 12.288MHz clock signal MUST
be applied to pin 109 (STS-1CLK/12M).
NOTE: This input pin is internally pulled low.
14
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS
PIN #
SIGNAL NAME
TYPE
107
E3Clk/ CLK_EN
I
DESCRIPTION
E3 Reference Clock Input/SFM Clock Output Enable:
The function of this chip depends upon whether or not the XRT75R03D has
been configured to operate in the Single-Frequency Mode.
If NOT operating in the Single-Frequency Mode
If the XRT75R03D has NOT been configured to operate in the SFM (Single Frequency) Mode, and if at least one channel is to be operated in the E3 Mode,
then a 34.368MHz ± 20ppm clock signal must be applied to this input pin.
If the user does not intend to operate the device in the SFM Mode nor operate
any of the channels in the E3 Mode tie this input signal to GND.
If operating in the Single-Frequency Mode
If the XRT75R03D is operated in the SFM Mode and is to output a clock signal
that is synthesized from the SFM Clock Synthesizer PLL so that the user's system can use this clock signal as a timing source, pull this input pin to a logic
"High".
If the user pull this input pin "High", then the XRT75R03D will output the line
rate clock signal that has been synthesized for Channel 1, via pin 108 (DS3CLK/
CLK_OUT).
For example, if Channel 1 is configured to operate in the STS-1 Mode and this
input pin is pulled "High", then the XRT75R03D will output a 51.84MHz clock
signal via the CLK_OUT pin.
15
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
SYSTEM-SIDE RECEIVE OUTPUT AND RECEIVE CONTROL PINS
PIN #
SIGNAL NAME
TYPE
108
DS3Clk/ CLK_OUT
I/O
DESCRIPTION
DS3 Reference Clock Input/SFM Synthesizer Clock Output:
The function of this chip depends upon whether or not the XRT75R03D has
been configured to operate in the SFM Mode.
If NOT operating in the Single-Frequency Mode
If the XRT75R03D has NOT been configured to operate in the SFM Mode, and
if at least one channel of the XRT75R03D is configured in the DS3 Mode, then
a clock signal with a frequency of 44.736 MHz ± 20ppm must be applied to this
input pin.
If the XRT75R03D is not configured to operate in the SFM Mode and none of
the channels are to be operated in the DS3 Mode, tie this input signal to GND.
If operating in the Single-Frequency Mode
If the XRT75R03D is configured to operate in the SFM Mode, and if pin 107
(E3CLK/CLKEN) is pulled to a logic "High", then the SFM Clock Synthesizer
PLL generated line rate clock signal for Channel 1 will be output via this output
pin.
In this mode, this particular output pin can be used by the user's system as a
timing source.
109
STS-1Clk/ 12M
I
STS-1 Reference Clock Input/12.288MHz SFM Reference Clock Input:
The function of this pin depends upon whether or not the XRT75R03D has been
configured to operate in the SFM Mode.
If NOT operating in the Single-Frequency Mode
If the XRT75R03D has NOT been configured to operate in the SFM Mode and if
at least one channel is intended to operate in the STS-1 Mode, then the user
must supply a clock signal with a frequency of 51.84MHz ± 20ppm to this input
pin
If the XRT75R03D is not to be operatedin the SFM Mode and none of the channels are to be operated in the STS-1 Mode, tie this input signal to GND.
If operating in the Single-Frequency Mode
If the XRT75R03D has been configured to operate in the SFM Mode a clock signal with a frequency of 12.288MHz ± 20ppm MUST be applied to this input pin.
The SFM Synthesizer will then synthesize all of the appropriate line rate frequencies (e.g., 34.368MHz for E3, 44.736MHz for DS3, and 51.84MHz for STS1) based upon this 12.288MHz Reference Clock source.
16
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
RECEIVE LINE SIDE PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
79
RTIP_0
I
91
RTIP_1
Receive TIP Input - Channel 1:
88
RTIP_2
Receive TIP Input - Channel 2:
Receive TIP Input - Channel 0:
These input pins along with the corresponding RRing_n input pin function as the
Receive DS3/E3/STS-1 Line input signal receiver for a given channel of the
XRT75R03D.
Connect this signal and the corresponding RRING_n input signal to a 1:1 transformer.
Whenever the RTIP/RRING input pins are receiving a positive-polarity pulse
within the incoming DS3, E3 or STS-1 line signal, then this input pin will be
pulsed to a "higher-voltage" than its corresponding RRING_n input pin.
Conversely, whenever the RTIP/RRING input pins are receiving a negativepolarity pulse within the incoming DS3, E3 or STS-1 line signal, then this input
pin will be pulsed to a "lower-voltage" than its corresponding RRING_n input
pin.
78
RRing_0
92
RRing_1
I
Receive Ring Input - Channel 1:
87
RRing_2
Receive Ring Input - Channel 2:
Receive Ring Input - Channel 0:
These input pins along with the corresponding RTIP_n input pin function as the
Receive DS3/E3/STS-1 Line input signal receiver for a given channel of the
XRT75R03D.
Connect this signal and the corresponding RTIP_n input signal to a 1:1 transformer.
Whenever the RTIP/RRING input pins are receiving a positive-polarity pulse
within the incoming DS3, E3 or STS-1 line signal, then this input pin will be
pulsed to a "lower-voltage" than its corresponding RTIP_n input pin.
Conversely, whenever the RTIP/RRING input pins are receiving a negativepolarity pulse within the incoming DS3, E3 or STS-1 line signal, then this input
pin will be pulsed to a "higher-voltage" than its corresponding RTIP_n input pin.
17
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
GENERAL CONTROL PINS
PIN #
SIGNAL NAME
TYPE
65
SR/DR
I
DESCRIPTION
Single-Rail/Dual-Rail Select Input - Chip Level
This input pin is used to configure the XRT75R03D to operate in either the Single-Rail or Dual-Rail Mode.
If the XRT75R03D is configured to operate in the Single-Rail Mode, then all of
the following will happen.
• All of the B3ZS/HDB3 Encoder and Decoder blocks in the XRT75R03D will be
enabled.
• The Transmit Section of each channel will accept all of the outbound data
from the System-side Equipment via the TPDATA_n (or TxDATA_n) input pin.
• The Receive Section of each channel will output all of the recovered data to
the System-side Equipment via the RPOS output pin.
• Each of the RNEG/LCV output pins will now function as the LCV (Line Code
Violation or Excessive Zero Event) indicator output pin.
If the user configures the device to operate in the Dual-Rail Mode, then all of the
following will happen.
• All of the B3ZS/HDB3 Encoder and Decoder blocks in the XRT75R03D will be
disabled.·
• The Transmit Section of each channel will accept positive-polarity data via the
TPDATA_n input pin, and negative-polarity data via the TNDATA_n input pin.
• The Receive Section of each channel will pulse the RPOS_n output pin "High"
for one period of RCLK_n for each time a positive-polarity pulse is received via
the RTIP_n/RRING_n input pins
• Likewise, the Receive Section of each channel will also pulse the RNEG_n
output pin "High" for one period of RCLK_n for each time a negative-polarity
pulse is received via the RTIP_n/RRING_n input pins.
"Low" - Configures the XRT75R03D to operate in the Dual-Rail Mode.
"High" - Configures the XRT75R03D to operate in the Single-Rail Mode.
NOTES:
1. This input pin is ignored and should be tied to GND if the XRT75R03D
has been configured to operate in the Host Mode.
2. This pin is internally pulled "Low".
76
E3_0
I
E3 Mode Select Input - Channel 0
94
E3_1
E3 Mode Select Input - Channel1
85
E3_2
E3 Mode Select Input - Channel 2
This input pin, along with the corresponding STS-1/DS3_n input pin is used the
to configure a given channel within the XRT75R03D into either the DS3, E3 or
STS-1 Modes.
"High" - Configures the corresponding channel to operate in the E3 Mode.
"Low" - Configures the corresponding channel to operate in either the DS3 or
STS-1 Modes, depending upon the setting of the corresponding STS-1/DS3_n
input pin.
NOTES:
1. This input pin is ignored and should be tied to GND if the XRT75R03D
has been configured to operate in the Host Mode.
2. This input pin is internally pulled low.
18
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
GENERAL CONTROL PINS
PIN #
SIGNAL NAME
TYPE
DESCRIPTION
72
STS-1/DS3_0
I
98
STS-1/DS3_1
STS-1/DS3 Select Input - Channel 1
81
STS-1/DS3_2
STS-1/DS3 Select Input - Channel 2
STS-1/DS3 Select Input - Channel 0
This input pin, along with the corresponding E3_n input pin is used the to configure a given channel within the XRT75R03D into either the DS3, E3 or STS-1
Modes.
"High" - Configures the corresponding channel to operate in the STS-1 Mode
provided that the corresponding E3_n input pin is pulled "Low".
"Low" - Configures the corresponding channel to operate in DS3 Mode provided
that the corresponding E3_n input pin is pulled "Low".
NOTES:
1. This input pin is ignored and should be tied to GND if the XRT75R03D
has been configured to operate in the Host Mode or if the
corresponding E3_n input pin is pulled "High".
2. This input pin is internally pulled low.
74
RLB_0
I
96
RLB_1
Remote Loop-back - RLB Input - Channel 1:
83
RLB_2
Remote Loop-back - RLB Input - Channel 2:
Remote Loop-back - RLB Input - Channel 0:
This input pin along with LLB_n is used to configure different Loop-Back modes.
NOTE:
I
RLB_n
LLB_n
Loopback Mode
0
0
Normal (No Loop-Back) Mode
0
1
Analog Loop-Back Mode
1
0
Remote Loop-Back Mode
1
1
Digital Local Loop-Back Mode
This input pin is ignored and should be connected to GND if the
XRT75R03D is operating in the HOST Mode.
73
LLB_0
Loop-Back Select - LLB Input - Channel 0
97
LLB_1
Loop-Back Select - LLB Input - Channel 1
82
LLB_2
Loop-Back Select - LLB Input - Channel 2
Please see description above for RLB_n
102
TEST
****
Factory Test Mode Input Pin
This pin must be connected to GND for normal operation.
NOTE: This input pin is internally pulled "Low".
19
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
GENERAL CONTROL PINS
PIN #
SIGNAL NAME
TYPE
62
ICT
I
DESCRIPTION
In-Circuit Test Input:
Setting this pin "Low" causes all digital and analog outputs to go into a highimpedance state to allow for in-circuit testing. For normal operation, set this pin
"High".
NOTE: This pin is internally pulled “High".
70
HOST/HW
I
HOST/Hardware Mode Select:
Tie this pin “High” to configure the XRT75R03D in HOST mode. Tie this “Low” to
configure in Hardware mode.
When the XRT75R03D is configured in HOST mode, the states of many of the
discrete input pins are controlled by internal register bits.
NOTE: This pin is internally pulled up.
CONTROL AND ALARM INTERFACE
PIN #
SIGNAL NAME
TYPE
122
RXA
****
DESCRIPTION
External Resistor of 3.01K Ω ± 1%.
Should be connected between RxA and RxB for internal bias.
123
RXB
****
External Resistor of 3.01K Ω ± 1%.
Should be connected between RxA and RxB for internal bias.
JITTER ATTENUATOR INTERFACE
PIN #
SIGNAL NAME
TYPE
44
JA0
I
DESCRIPTION
Jitter Attenuator Select 0:
In Hardware Mode, this pin along with pin 42 configures the Jitter Attenuator as
shown in the table below.
JA0
JA1
Mode
0
0
FIFO Depth = 16 bits
0
1
FIFO Depth = 32 bits
1
0
SONET/SDH De-Sync
Mode
1
1
Jitter Attenuator Disabled
NOTES:
1. The setting of these input pins applies globally to all three (3) channels
in the XRT75R03D.
2. This input pin is ignored and should be tied to GND if the XRT75R03D
is configured to operate in the Host Mode.
20
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
JITTER ATTENUATOR INTERFACE
42
JA1
I
Jitter Attenuator Select 1:
Please see the Description above for JA0
43
JATx/Rx
I
Jitter Attenuator in Transmit/Receive Path Select Input:
This input pin is used to configure the Jitter Attenuator to operate in either the
Transmit or Receive path within each of the three (3) channels of the
XRT75R03D.
"Low" - Configures the Jitter Attenuator within each channel to operate in the
Receive Path.
"High" - Configures the Jitter Attenuator within each channel to operate in the
Transmit Path.
NOTES:
1. The setting of this input pin applies globally to all three (3) channels of
the XRT75R03D.
2. This input pin is ignored and should be tied to GND if the XRT75R03D
is configured to operate in the Host Mode or if the Jitter Attenuators
are disabled.
MICROPROCESSOR SERIAL INTERFACE - (HOST MODE)
PIN #
SIGNAL NAME
TYPE
69
SDO/RxMON
I/O
DESCRIPTION
Microprocessor Serial Interface - Serial Data Output:
This pin serially outputs the contents of a specified on-chip Command Register
during READ Operations via the Microprocessor Serial Interface. The data
which is output via this pin is updated upon the falling edge of the SCLK clock
signal.
This output pin will be tri-stated upon completion of a given READ operation.
NOTE: This pin functions as the RxMON input pin if the XRT75R03D has been
configured to operate in the Hardware Mode.
68
SDI/RxON
I
Microprocessor Serial Interface - Serial Data Input:
This input pin functions as the Serial Data Input pin for the Microprocessor
Serial Interface. In particular, this input pin will accept all of the following data in
a serial manner during READ and WRITE operations with the Microprocessor
Serial Interface.
• The READ/WRITE indicator bit.
• The Address Value of the Targeted Command Register for this particular
READ or WRITE operation.
• The Data to be written into the targeted Command Register for a given
WRITE operation.
All data that is applied to this input will be sampled upon the rising edge of the
SCLK input clock signal.
NOTE: This input pin will function as the RxON input pin if the XRT75R03D has
been configured to operate in the Hardware Mode.
21
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
MICROPROCESSOR SERIAL INTERFACE - (HOST MODE)
PIN #
SIGNAL NAME
TYPE
67
SClk/TCLKINV
I
DESCRIPTION
Microprocessor Serial Interface -Serial Clock Input:
This input pin functions as the Clock Source for the Microprocessor Serial Interface.
Each time the user wishes to perform a READ or WRITE operate with the onchip Command Registers via the Microprocessor Serial Interface, the user
MUST do the following.
• Assert the CS input pin by toggling it "Low", and
• Provide 16 Clock Periods to this particular input pin for each READ and
WRITE operation.
The Microprocessor Serial Interface will sample any data residing upon the SDI
input pin, upon the rising edge of this clock signal. Further, for READ operations, the Microprocessor Serial Interface will serially output the contents of a
target Command Register upon the falling edge of this clock signal.
NOTE: The maximum frequency of this particular clock signal is 10MHz.
66
CS/RCLKINV
I
Microprocessor Serial Interface - Chip Select Input:
This input pin should be pulled "Low" whenever a READ or WRITE operation is
to be executed to the on-chip Command Registers, via the Microprocessor
Serial Interface.
This input pin should remain "Low" until the READ or WRITE operation has
been completed. This input pin should be pulled "High" at all other times.
NOTE: If the XRT75R03D has been configured to operate in the Host Mode
then this input pin will function as the RCLKINV input pin.
71
INT/LOSMUT
O
Microprocessor Serial Interface - Interrupt Request Output:
If the XRT75R03D has been configured to operate in the Host Mode, then this
pin becomes the Interrupt Request Output for the XRT75R03D.
During normal conditions, this output pin will be pulled "High". However, if the
user enables certain interrupts within the device, and if those conditions occur,
then the XRT75R03D will request an interrupt from the Microprocessor by toggling this output pin "Low".
NOTES:
1. If the XRT75R03D is configured to operate in the Hardware Mode,
then this pin functions as the LOSMUT input pin.
2. This pin will remain "Low" until the Interrupt has been served.
101
RESET
I
Microprocessor Serial Interface - H/W RESET Input:
Pulsing this input "Low" causes the XRT75R03D to reset the contents of the onchip Command Registers to their default values. As a consequence, the
XRT75R03D will then also be operating in its default condition.
For normal operation pull this input pin to a logic "High".
NOTE: This input pin is internally pulled high.
22
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
POWER SUPPLY AND GROUND PINS
PIN #
PIN NAME
TYPE
DESCRIPTION
RECEIVE ANALOG VDD
77
RxAVDD_0
93
RxAVDD_1
86
RxAVDD_2
****
TRANSMIT ANALOG VDD
39
TxAVDD_0
128
TxAVDD_1
23
TxAVDD_2
121
REFAVDD
****
JITTER ATTENUATOR ANALOG VDD
46
JAVDD_0
120
JAVDD_1
45
JAVDD_2
****
DIGITAL VDD
29
TxVDD_0
12
TxVDD_1
20
TxVDD_2
55
RxDVDD_0
111
RxDVDD_1
54
RxDVDD_2
119
JADVDD
110
EXDVDD
****
23
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
POWER SUPPLY AND GROUND PINS
PIN #
PIN NAME
TYPE
DESCRIPTION
GROUNDS
41
TxAGND_0
126
TxAGND_1
15
TxAGND_2
80
RxAGND_0
90
RxAGND_1
89
RxAGND_2
47
JAGND_0
118
JAGND_1
48
JAGND_2
49
AGND_0
116
AGND_1
100
AGND_2
124
REFGND
27
TxGND_0
14
TxGND_1
18
TxGND_2
59
RxDGND_0
115
RxDGND_1
50
RxDGND_2
117
JADGND
105
EXDGND
****
24
REV. 1.0.2
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
XRT75R03D PIN LISTING IN NUMERICAL ORDER
PIN #
PIN NAME
TYPE
1
TxON_1
I
2
TNDATA_1
I
3
TPDATA_1
I
4
TCLK_1
I
5
MRING_1
I
6
MTIP_1
I
7
TAOS_1
I
COMMENTS
This input pin is internally pulled ’High’.
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
8
TAOS_2
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
9
TxLEV_1
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
10
TxLEV_2
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
11
TTIP_1
O
12
DVDD
***
13
TRING_1
O
14
TxAGND_1
***
15
TxAGND_2
***
16
MRING_2
I
17
MTIP_2
I
18
GND
***
19
TRING_2
O
20
TxVDD_2
***
21
TTIP_2
O
22
DMO_2
O
23
TxAVDD_2
***
24
TNDATA_2
I
25
TPDATA_2
I
26
TCLK_2
I
27
TxGND_0
***
28
TRING_0
O
29
TxVDD_0
***
30
TTIP_0
O
25
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
XRT75R03D PIN LISTING IN NUMERICAL ORDER
PIN #
PIN NAME
TYPE
31
MTIP_0
I
32
MRING_0
I
33
TNDATA_0
I
34
TPDATA_0
I
35
TAOS_0
I
36
TxLEV_0
I
COMMENTS
Not Active while in Host Mode
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
37
TAOS_0
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
38
TxON_0
I
This input pin is internally pulled ’High’.
39
TxAVDD_0
***
40
DMO_0
O
41
TxAGND_0
***
42
JA1
I
Not Active while in Host Mode
43
JATx/Rx
I
Not Active while in Host Mode
44
JA0
I
Not Active while in Host Mode
45
JAVDD_2
***
46
JAVDD_0
***
47
JAGND_0
***
48
JAGND_2
***
49
AGND_0
***
50
RxDGND_2
***
51
RCLK_2
O
52
RNEG_2/LCV_2
O
53
RPOS_2
O
54
RxDVDD_2
***
55
RxDVDD_0
***
56
RCLK_0
O
57
RNEG_0/LCV_0
O
58
RPOS_0
O
59
RxDGND_0
***
60
RLOS_0
O
61
RLOL_0
O
62
ICT
I
This input pin is internally pulled low.
26
REV. 1.0.2
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
XRT75R03D PIN LISTING IN NUMERICAL ORDER
PIN #
PIN NAME
TYPE
63
RLOS_2
O
64
RLOL_2
O
65
SR/DR
I
COMMENTS
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
66
RCLKINV (CS)
I
67
TCLKINV (SCLK)
I
68
RxON (SDI)
I
69
RxMON (SDO)
I/O
70
HOST/HW
I
71
LOSMUT (INT)
I/O
72
STS-1/DS3_0
I
This input pin is internally pulled low.
This input pin is internally pulled low.
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
73
LLB_0
I
Not Active while in Host Mode
74
RLB_0
I
Not Active while in Host Mode
75
REQEN_0
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
76
E3_0
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
77
RxAVDD_0
***
78
RRING_0
I
79
RTIP_0
I
80
RxAGND_0
***
81
STS-1/DS3_2
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
82
LLB_2
I
Not Active while in Host Mode
83
RLB_2
I
Not Active while in Host Mode
84
REQEN_2
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
85
E3_2
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
86
RxAVDD_2
***
87
RRING_2
I
88
RTIP_2
I
89
RxAGND_2
***
90
RxAGND_1
***
91
RTIP_1
I
27
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
XRT75R03D PIN LISTING IN NUMERICAL ORDER
PIN #
PIN NAME
TYPE
92
RRING_1
I
93
RxAVDD_1
***
94
E3_1
I
COMMENTS
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
95
REQEN_1
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
96
RLB_1
I
Not Active while in Host Mode
97
LLB_1
I
Not Active while in Host Mode
98
STS-1/DS3_1
I
1. Not Active while in Host Mode
2. This input pin is internally pulled low.
99
LOSTHR
I
100
AGND_2
***
101
RESET
I
This input pin is internally pulled high.
102
TEST
I
This input pin is internally pulled low.
103
RLOL_1
O
104
RLOS_1
O
105
EXDGND
***
106
SFM_EN
I
107
E3CLK/CLK_EN
I
108
DS3CLK/
CLK_OUT
I/O
109
STS-1CLK/12M
I
110
EXDVDD
***
111
RxDVDD_1
***
112
RPOS_1
O
113
RNEG_1/LCV_1
O
114
RCLK_1
O
115
RxDGND_1
***
116
AGND_1
***
117
JADGND
***
118
JAGND_1
***
119
JADVDD
***
120
JADVDD_1
***
121
REFAVDD
***
122
RXA
***
This input pin is internally pulled low.
28
REV. 1.0.2
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
XRT75R03D PIN LISTING IN NUMERICAL ORDER
PIN #
PIN NAME
TYPE
123
RXB
***
124
REFGND
***
125
TxON_2
I
126
TxAGND_1
***
127
DMO_1
O
128
TxAVDD_1
***
COMMENTS
This input pin is internally pulled ’High’.
29
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
1.0 R3 TECHNOLOGY (RECONFIGURABLE, RELAYLESS REDUNDANCY)
Redundancy is used to introduce reliability and protection into network card design. The redundant card in
many cases is an exact replicate of the primary card, such that when a failure occurs the network processor
can automatically switch to the backup card. EXAR’s R3 technology has re-defined E3/DS-3/STS-1 LIU design
for 1:1 and 1+1 redundancy applications. Without relays and one Bill of Materials, EXAR offers multi-port,
integrated LIU solutions to assist high density agregate applications and framing requirements with reliability.
The following section can be used as a reference for implementing R3 Technology with EXAR’s world leading
line interface units.
1.1
Network Architecture
A common network design that supports 1:1 or 1+1 redundancy consists of N primary cards along with N
backup cards that connect into a mid-plane or back-plane architecture without transformers installed on the
network cards. In addition to the network cards, the design has a line interface card with one source of
transformers, connectors, and protection components that are common to both network cards. Wtih this
design, the bill of materials is reduced to the fewest amount of components. See Figure 3 for a simplified block
diagram of a typical redundancy design.
FIGURE 3. NETWORK REDUNDANCY ARCHITECTURE
GND
37.5Ω
Rx
Framer/
Mapper
37.5Ω
1:1
0.01µF
0.01µF
LIU
31.6Ω
Tx
31.6Ω
1:1
Line Interface Card
Primary Line Card
0.01µF
Rx
Framer/
Mapper
0.01µF
LIU
31.6Ω
Tx
31.6Ω
Redundant Line Card
Back
Plane
or
Mid
Plane
1.2
Power Failure Protection
EXAR’s "High" impedance circuits protect the LIU and preserve the line impedance characteristics when a
power failure occurs. As the power supply decreases to a pre-determined voltage, the I/O pads are
automatically switched to "High" impedance. This effectively removes the LIU, preventing a line impedance
mismatch or system degradation. Power failures or network card hot swapping change the network circuit. It
is critical that under these circumstances, that the primary card still behaves according to network standards.
The three sensitive specifications are pulse mask conformance, receive sensitivity and return loss. Each must
be carefully characterized to ensure network integrity and reliability.
1.3
Software vs Hardware Automatic Protection Switching
The implementation of R3 technology can be controlled through programming the internal registers or through
the use of the TxON hardware pin available within the LIU. To use software to tri-state the transmitters, first the
TxON pin must be pulled "High". Once the pin is pulled "High", the individual register bits can be used to
control the output activity of the transmit path. To use the TxON pin, the individual register bits can be set
"High", and the control of the transmitters is handled by setting the state of the TxON pin.
30
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
2.0 ELECTRICAL CHARACTERISTICS
TABLE 1: ABSOLUTE MAXIMUM RATINGS
SYMBOL
PARAMETER
MIN
MAX
UNITS
COMMENTS
VDD
Supply Voltage
-0.5
6.0
V
Note 1
VIN
Input Voltage at any Pin
-0.5
5.5
V
Note 1
IIN
Input current at any pin
100
mA
Note 1
STEMP
Storage Temperature
-65
150
0
C
Note 1
ATEMP
Ambient Operating Temperature
-40
85
0
C
linear airflow 0 ft./min
Theta JA
Thermal Resistance
C/W
linear air flow 0ft/min
23
0
(See Note 3 below)
MLEVL
Exposure to Moisture
5
level
EIA/JEDEC
JESD22-A112-A
ESD
ESD Rating
2000
V
Note 2
NOTES:
1. Exposure to or operating near the Min or Max values for extended period may cause permanent failure and impair
reliability of the device.
2. ESD testing method is per MIL-STD-883D,M-3015.7
3. With Linear Air flow of 200 ft/min, reduce Theta JA by 20%, Theta JC is unchanged.
TABLE 2: DC ELECTRICAL CHARACTERISTICS:
PARAMETER
SYMBOL
MIN.
TYP.
MAX.
UNITS
DVDD
Digital Supply Voltage
3.135
3.3
3.465
V
AVDD
Analog Supply Voltage
3.135
3.3
3.465
V
ICC
Supply current requirements
410
470
mA
PDD
Power Dissipation
1.1
1.2
W
VIL
Input Low Voltage
0.8
V
VIH
Input High Voltage
5.5
V
VOL
Output Low Voltage, IOUT = - 4mA
0.4
V
VOH
Output High Voltage, IOUT = 4 mA
2.0
2.4
V
IL
Input Leakage Current1
±10
µA
CI
Input Capacitance
10
pF
CL
Load Capacitance
10
pF
NOTES:
1.
Not applicable for pins with pull-up or pull-down resistors.
2. The Digital inputs and outputs are TTL 5V compliant.
31
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
3.0 TIMING CHARACTERISTICS
FIGURE 4. TYPICAL INTERFACE BETWEEN TERMINAL EQUIPMENT AND THE XRT75R03D (DUAL-RAIL DATA)
Terminal
Equipment
(E3/DS3 or STS-1
Framer)
TxPOS
TPData
TxNEG
TNData
TxLineClk
TxClk
Transmit
Logic
Block
Exar E3/DS3/STS-1 LIU
FIGURE 5. TRANSMITTER TERMINAL INPUT TIMING
t RTX
t FTX
TxClk
t TSU
t THO
TPData or
TNData
TTIP or
TRing
SYMBOL
TxClk
t TDY
PARAMETER
Duty Cycle
MIN
TYP
MAX
UNITS
30
50
70
%
E3
34.368
MHz
DS3
44.736
MHz
STS-1
51.84
MHz
tRTX
TxClk Rise Time (10% to 90%)
4
ns
tFTX
TxClk Fall Time (10% to 90%)
4
ns
tTSU
TPData/TNData to TxClk falling set up time
3
ns
tTHO
TPData/TNData to TxClk falling hold time
3
ns
tTDY
TTIP/TRing to TxClk rising propagation delay time
32
8
ns
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
FIGURE 6. RECEIVER DATA OUTPUT AND CODE VIOLATION TIMING
tRRX
tFRX
RClk
tLCVO
LCV
tCO
RPOS or
RNEG
SYMBOL
RxClk
PARAMETER
Duty Cycle
MIN
TYP
MAX
UNITS
45
50
55
%
E3
34.368
MHz
DS3
44.736
MHz
STS-1
51.84
MHz
tRRX
RxClk rise time (10% o 90%)
2
4
ns
tFRX
RxClk falling time (10% to 90%)
2
4
ns
tCO
RxClk to RPOS/RNEG delay time
4
ns
tLCVO
RxClk to rising edge of LCV output delay
2.5
ns
FIGURE 7. TRANSMIT PULSE AMPLITUDE TEST CIRCUIT FOR E3, DS3 AND STS-1 RATES
R1
TTIP(n)
31.6Ω +1%
TxPOS(n)
TxNEG(n)
TxLineClk(n)
TPData(n)
TNData(n)
TxClk(n)
R3
75Ω
1:1
31.6Ω + 1%
TRing(n)
R2
XRT75R03D (0nly one channel shown)
33
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
4.0 LINE SIDE CHARACTERISTICS:
4.1
E3 line side parameters:
The XRT75R03D line output at the transformer output meets the pulse shape specified in ITU-T G.703 for
34.368 Mbits/s operation. The pulse mask as specified in ITU-T G.703 for 34.368 Mbits/s is shown in Figure 7.
FIGURE 8. PULSE MASK FOR E3 (34.368 MBITS/S) INTERFACE AS PER ITU-T G.703
17 ns
(14.55 + 2.45)
8.65 ns
V = 100%
Nominal Pulse
50%
14.55ns
12.1ns
(14.55 - 2.45)
10%
0%
10%
20%
34
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE 3: E3 TRANSMITTER LINE SIDE OUTPUT AND RECEIVER LINE SIDE INPUT SPECIFICATIONS
PARAMETER
MIN
TYP
MAX
UNITS
0.90
1.00
1.10
Vpk
Transmit Output Pulse Amplitude Ratio
0.95
1.00
1.05
Transmit Output Pulse Width
12.5
14.55
16.5
ns
0.02
0.05
UIPP
TRANSMITTER LINE SIDE OUTPUT CHARACTERISTICS
Transmit Output Pulse Amplitude
(Measured at secondary of the transformer)
Transmit Intrinsic Jitter
RECEIVER LINE SIDE INPUT CHARACTERISTICS
Receiver Sensitivity (length of cable)
900
1200
feet
Interference Margin
-20
-14
dB
Jitter Tolerance @ Jitter Frequency 800KHz
0.15
0.28
UI PP
Signal level to Declare Loss of Signal
-35
dB
Signal Level to Clear Loss of Signal
-15
Occurence of LOS to LOS Declaration Time
10
255
UI
Termination of LOS to LOS Clearance Time
10
255
UI
NOTE: The above values are at TA = 250C and VDD = 3.3 V± 5%.
35
dB
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
FIGURE 9. BELLCORE GR-253 CORE TRANSMIT OUTPUT PULSE TEMPLATE FOR SONET STS-1 APPLICATIONS
ST S-1 Pulse T emplate
1.2
1
Norm a liz e d Am plitude
0.8
0.6
Lower Curve
Upper Curve
0.4
0.2
0
2
3
4
1.
1.
1.
1
1
8
9
0.
0.
1.
6
7
0.
0.
4
5
0.
0.
2
3
0.
0.
0
1
1
-0
.
0.
3
2
-0
.
-0
.
5
4
-0
.
-0
.
7
6
-0
.
-0
.
9
8
-0
.
-0
.
-1
-0.2
Time, in UI
TABLE 4: STS-1 PULSE MASK EQUATIONS
TIME IN UNIT INTERVALS
NORMALIZED AMPLITUDE
LOWER CURVE
- 0.03
-0.85 < T < -0.38
-0.38
·
π
T 
0.5 1 + sin  ---  1 + -----------   – 0.03
0.18
2


< T < 0.36
- 0.03
0.36 < T < 1.4
UPPER CURVE
-0.85 < T < -0.68
0.03
-0.68 < T < 0.26
·
π
T 
0.5 1 + sin  --- 1 + -----------   + 0.03


0.34
2


0.26 < T < 1.4
0.1 + 0.61 x e-2.4[T-0.26]
36
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE 5: STS-1 TRANSMITTER LINE SIDE OUTPUT AND RECEIVER LINE SIDE INPUT SPECIFICATIONS (GR-253)
PARAMETER
MIN
TYP
MAX
UNITS
0.65
0.75
0.9
Vpk
0.90
1.00
1.10
Vpk
Transmit Output Pulse Width
8.6
9.65
10.6
ns
Transmit Output Pulse Amplitude Ratio
0.90
1.00
1.10
0.02
0.05
TRANSMITTER LINE SIDE OUTPUT CHARACTERISTICS
Transmit Output Pulse Amplitude
(measured with TxLEV = 0)
Transmit Output Pulse Amplitude
(measured with TxLEV = 1)
Transmit Intrinsic Jitter
UIpp
RECEIVER LINE SIDE INPUT CHARACTERISTICS
Receiver Sensitivity (length of cable)
900
Jitter Tolerance @ Jitter Frequency 400 KHz
0.15
1100
feet
UIpp
Signal Level to Declare Loss of Signal
Refer to Table 10
Signal Level to Clear Loss of Signal
Refer to Table 10
NOTE: The above values are at TA = 250C and VDD = 3.3 V ± 5%.
FIGURE 10. TRANSMIT OUPUT PULSE TEMPLATE FOR DS3 AS PER BELLCORE GR-499
DS3 Pulse T emplate
1.2
1
0.6
Lower Curve
Upper Curve
0.4
0.2
0
37
2
3
4
1.
1.
1.
1
0.
1
8
9
0.
1.
6
7
0.
4
5
0.
0.
Tim e , in UI
0.
2
3
0.
0.
0
1
1
-0
.
0.
3
2
-0
.
5
4
-0
.
-0
.
-0
.
7
6
-0
.
-0
.
-0
.
9
8
-0
.
-0.2
-1
Norm a lize d Am plitude
0.8
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 6: DS3 PULSE MASK EQUATIONS
TIME IN UNIT INTERVALS
NORMALIZED AMPLITUDE
LOWER CURVE
- 0.03
-0.85 < T < -0.36
-0.36
·
π
T 
0.5 1 + sin  --- 1 + -----------   – 0.03


2
0.18


< T < 0.36
- 0.03
0.36 < T < 1.4
UPPER CURVE
-0.85 < T < -0.68
0.03
-0.68 < T < 0.36
·
π
T 
0.5 1 + sin  --- 1 + -----------   + 0.03


0.34
2


0.36 < T < 1.4
0.08 + 0.407 x e-1.84[T-0.36]
TABLE 7: DS3 TRANSMITTER LINE SIDE OUTPUT AND RECEIVER LINE SIDE INPUT SPECIFICATIONS (GR-499)
PARAMETER
MIN
TYP
MAX
UNITS
0.65
0.75
0.85
Vpk
0.90
1.00
1.10
Vpk
Transmit Output Pulse Width
10.10
11.18
12.28
ns
Transmit Output Pulse Amplitude Ratio
0.90
1.00
1.10
0.02
0.05
TRANSMITTER LINE SIDE OUTPUT CHARACTERISTICS
Transmit Output Pulse Amplitude
(measured with TxLEV = 0)
Transmit Output Pulse Amplitude
(measured with TxLEV = 1)
Transmit Intrinsic Jitter
UIpp
RECEIVER LINE SIDE INPUT CHARACTERISTICS
Receiver Sensitivity (length of cable)
900
Jitter Tolerance @ 400 KHz (Cat II)
0.15
1100
UIpp
Signal Level to Declare Loss of Signal
Refer to Table 10
Signal Level to Clear Loss of Signal
Refer to Table 10
NOTE: The above values are at TA = 250C and VDD = 3.3V ± 5%.
38
feet
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
FIGURE 11. MICROPROCESSOR SERIAL INTERFACE STRUCTURE
CS
SClk
1
SDI
R/W
2
3
A0
4
A1
A2
5
A3
6
A4
7
A5
8
0
9
10
11
12
13
14
15
16
D0
D1
D2
D3
D4
D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
High Z
High Z
SDO
NOTE: If the R/W bit is set to "1", then this denotes a "READ" operation with the Microprocessor Serial Interface.
Conversely, if the R/W bit is set to "0", then this denotes a "WRITE" operation.
FIGURE 12. TIMING DIAGRAM FOR THE MICROPROCESSOR SERIAL INTERFACE
t28
t21
CS
t26
t27
t24
SCLK
t23
t22
SDI
t25
A0
R/W
A1
CS
SCLK
t30
t29
SDO
SDI
Hi-Z
D0
t32
t31
D2
D1
D7
Hi-Z
TABLE 8: MICROPROCESSOR SERIAL INTERFACE TIMINGS ( TA = 250C, VDD=3.3V± 5% AND LOAD = 10PF)
SYMBOL
PARAMETER
MIN.
TYP.
MAX
UNITS
t21
CS Low to Rising Edge of SClk
5
ns
t22
SDI to Rising Edge of SClk
5
ns
t23
SDI to Rising Edge of SClk Hold Time
5
ns
39
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 8: MICROPROCESSOR SERIAL INTERFACE TIMINGS ( TA = 250C, VDD=3.3V± 5% AND LOAD = 10PF)
SYMBOL
PARAMETER
MIN.
TYP.
MAX
UNITS
t24
SClk "Low" Time
50
ns
t25
SClk "High" Time
50
ns
t26
SClk Period
100
ns
t27
Falling Edge of SClk to rising edge of CS
0
ns
t28
CS Inactive Time
50
ns
t29
Falling Edge of SClk to SDO Valid Time
20
ns
t30
Falling Edge of SClk to SDO Invalid Time
10
ns
t31
Rising edge of CS to High Z
25
ns
t32
Rise/Fall time of SDO Output
5
ns
40
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
FUNCTIONAL DESCRIPTION:
Figure 1 shows the functional block diagram of the device. Each channel can be independently configured
either by Hardware Mode or by Host Mode to support E3, DS3 or STS-1 modes. A detailed operation of each
section is described below.
Each channel consists of the following functional blocks:
5.0 THE TRANSMITTER SECTION:
The Transmitter Section, within each Channel, accepts TTL/CMOS level signals from the Terminal Equipment
in selectable data formats.
• Convert the CMOS level B3ZS or HDB3 encoded data into pulses with shapes that are compliant with the
various industry standard pulse template requirements. Figures 7, 8 and 9 illustrate the pulse template
requirements.
• Encode the un-encoded NRZ data into either B3ZS format for (DS3 or STS-1) or HDB3 format (for E3) and
convert to pulses with shapes and width that are compliant with industry standard pulse template
requirements. Figures 7, 8 and 9 illustrate the pulse template requirements.
• In Single-Rail or un-encoded Non-Return-to-Zero (NRZ) mode, data is input via TPData_n pins while
TNData_n pins must be grounded. The NRZ or Single-Rail mode is selected when the SR/DR input pin is
“High” (in Hardware Mode) or bit 0 of channel control register is “1” (in Host Mode). Figure 12 illustrates the
Single-Rail or NRZ format.
FIGURE 13. SINGLE-RAIL OR NRZ DATA FORMAT (ENCODER AND DECODER ARE ENABLED)
Data
1
1
0
TPData
TxClk
• In Dual-Rail mode, data is input via TPData_n and TNData_n pins. TPData_n contains positive data and
TNData_n contains negative data. The SR/DR input pin = “Low” (in Hardware Mode) or bit 0 of channel
register = “0” (in Host Mode) enables the Dual-Rail mode. Figure 13 illustrates the Dual-Rail data format.
FIGURE 14. DUAL-RAIL DATA FORMAT (ENCODER AND DECODER ARE DISABLED)
Data
1
1
TPData
TNData
TxClk
41
0
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
5.1
REV. 1.0.2
TRANSMIT CLOCK:
The Transmit Clock applied via TxClk_n pins, for the selected data rate (for E3 = 34.368 MHz, DS3 = 44.736
MHz or STS-1 = 51.84 MHz), is duty cycle corrected by the internal PLL circuit to provide a 50% duty cycle
clock to the pulse shaping circuit. This allows a 30% to 70% duty cycle Transmit Clock to be supplied.
5.2
B3ZS/HDB3 ENCODER:
When the Single-Rail (NRZ) data format is selected, the Encoder Block encodes the data into either B3ZS
format (for either DS3 or STS-1) or HDB3 format (for E3).
5.2.1
B3ZS Encoding:
An example of B3ZS encoding is shown in Figure 14. If the encoder detects an occurrence of three
consecutive zeros in the data stream, it is replaced with either B0V or 00V, where ‘B’ refers to Bipolar pulse that
is compliant with the Alternating polarity requirement of the AMI (Alternate Mark Inversion) line code and ‘V’
refers to a Bipolar Violation (e.g., a bipolar pulse that violates the AMI line code). The substitution of B0V or
00V is made so that an odd number of bipolar pulses exist between any two consecutive violation (V) pulses.
This avoids the introduction of a DC component into the line signal.
FIGURE 15. B3ZS ENCODING FORMAT
TClk
5.2.2
TPDATA
1
0
Line
Signal
1
0
1 1
1
0
0
0
0
0
0
V
0
1
1
0
0
0
0
1
0
0
0
0
B
0
V
0
0
0
B
V
0
V
HDB3 Encoding:
An example of the HDB3 encoding is shown in Figure 15. If the HDB3 encoder detects an occurrence of four
consecutive zeros in the data stream, then the four zeros are substituted with either 000V or B00V pattern. The
substitution code is made in such a way that an odd number of bipolar (B) pulses exist between any
consecutive V pulses. This avoids the introduction of DC component into the analog signal.
FIGURE 16. HDB3 ENCODING FORMAT
TClk
TPDATA
1
0
Line
Signal
1
0
1 1
1
0
0
0
0
0
0
0
V
1
1
1
42
0
0
0
0
0
0
0
V
0
0
0
0
B
0
0
V
0
B
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
NOTES:
1. When Dual-Rail data format is selected, the B3ZS/HDB3 Encoder is automatically disabled.
2. In Dual-Rail format, the Bipolar Violations in the incoming data stream is converted to valid data pulses.
3. Encoder and Decoder is enabled only in Single-Rail mode.
5.3
TRANSMIT PULSE SHAPER:
The Transmit Pulse Shaper converts the B3ZS encoded digital pulses into a single analog Alternate Mark
Inversion (AMI) pulse that meet the industry standard mask template requirements for STS-1 and DS3. See
Figures 8 and 9.
For E3 mode, the pulse shaper converts the HDB3 encoded pulses into a single full amplitude square shaped
pulse with very little slope. This is illustrated in Figure 7.
The Pulse Shaper Block also includes a Transmit Build Out Circuit, which can either be disabled or enabled by
setting the TxLEV_n input pin “High” or “Low” (in Hardware Mode) or setting the TxLEV_n bit to “1” or “0” in the
control register (in Host Mode).
For DS3/STS-1 rates, the Transmit Build Out Circuit is used to shape the transmit waveform that ensures that
transmit pulse template requirements are met at the Cross-Connect system. The distance between the
transmitter output and the Cross-Connect system can be between 0 to 450 feet.
For E3 rate, since the output pulse template is measured at the secondary of the transformer and since there is
no Cross-Connect system pulse template requirements, the Transmit Build Out Circuit is always disabled.
5.3.1
Guidelines for using Transmit Build Out Circuit:
If the distance between the transmitter and the DSX3 or STSX-1, Cross-Connect system, is less than 225 feet,
enable the Transmit Build Out Circuit by setting the TxLEV_n input pin “Low” (in Hardware Mode) or setting the
TxLEV_n control bit to “0” (in Host Mode).
If the distance between the transmitter and the DSX3 or STSX-1 is greater than 225 feet, disable the Transmit
Build Out Circuit.
5.3.2
Interfacing to the line:
The differential line driver increases the transmit waveform to appropriate level and drives into the 75Ω load as
shown in Figure 6.
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XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
Transmit Drive Monitor:
5.4
This feature is used for monitoring the transmit line for occurrence of fault conditions such as a short circuit on
the line or a defective line driver.
To activate this function, connect MTIP_n pins to the TTIP_n lines via a 270 Ω resistor and MRing_n pins to
TRing_n lines via 270 Ω resistor as shown in Figure 16.
FIGURE 17. TRANSMIT DRIVER MONITOR SET-UP.
R1
TTIP(n)
TxPOS(n)
TxNEG(n)
TxLineClk(n)
31.6Ω +1%
R3
75Ω
TPData(n)
TNData(n)
TxClk(n) TRing(n)
1:1
31.6Ω + 1%
R2
MTIP(n)
R4 270Ω
MRing(n)
R5 270Ω
XRT75R03D (0nly one channel shown)
When the MTIP_n and MRing_n are connected to the TTIP_n and TRing_n lines, the drive monitor circuit
monitors the line for transitions. The DMO_n (Drive Monitor Output) will be asserted “Low” as long as the
transitions on the line are detected via MTIP_n and MRing_n.
If no transitions on the line are detected for 128 ± 32 TxClk_n periods, the DMO_n output toggles “High” and
when the transitions are detected again, DMO_n toggles “Low”.
NOTE: The Drive Monitor Circuit is only for diagnostic purpose and does not have to be used to operate the transmitter.
Transmitter Section On/Off:
5.5
The transmitter section of each channel can either be turned on or off. To turn on the transmitter, set the input
pin TxON_n to “High” (in Hardware Mode) or write a “1” to the TxON_n control bits (in Host Mode) and TxON_n
pins tied “High”.
When the transmitter is turned off, TTIP_n and TRing_n are tri-stated.
NOTES:
1.
This feature provides support for Redundancy.
2.
If the XRT75R03D is configured in Host mode, to permit a system designed for redundancy to quickly shut-off the
defective line card and turn on the back-up line card, writing a “1” to the TxON_n control bits transfers the control
to TxON_n pins.
6.0 THE RECEIVER SECTION:
This section describes the detailed operation of the various blocks in the receiver. The receiver recovers the
TTL/CMOS level data from the incoming bipolar B3ZS or HDB3 encoded input pulses.
6.1
AGC/Equalizer:
The Adaptive Gain Control circuit amplifies the incoming analog signal and compensates for the various flat
losses and also for the loss at one-half symbol rate. The AGC has a dynamic range of 30 dB.
The Equalizer restores the integrity of the signal and compensates for the frequency dependent attenuation of
up to 900 feet of coaxial cable (1300 feet for E3). The Equalizer also boosts the high frequency content of the
44
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
signal to reduce Inter-Symbol Interference (ISI) so that the slicer slices the signal at 50% of peak voltage to
generate Positive and Negative data.
The Equalizer can either be “IN” or “OUT” by setting the REQEN_n pin “High” or “Low” (in Hardware Mode) or
setting the REQEN_n control bit to “1” or “0” (in Host Mode).
RECOMMENDATIONS FOR EQUALIZER SETTINGS:
The Equalizer has two gain settings to provide optimum equalization. In the case of normally shaped DS3/
STS-1 pulses (pulses that meet the template requirements) that has been driven through 0 to 900 feet of cable,
the Equalizer can be left “IN” by setting the REQEN_n pin to “High” (in Hardware Mode) or setting the
REQEN_n control bit to “1” (in Host Mode).
However, for square-shaped pulses such as E3 or for DS3/STS-1 high pulses (that does not meet the pulse
template requirements), it is recommended that the Equalizer be left “OUT” for cable length less than 300 feet
by setting the REQEN_n pin “Low” (in Hardware Mode) or by setting the REQEN_n control bit to “0” (in Host
Mode).This would help to prevent over-equalization of the signal and thus optimize the performance in terms of
better jitter transfer characteristics.
NOTE: The results of extensive testing indicates that even when the Equalizer was left “IN” (REQEN_n = “HIGH”),
regardless of the cable length, the integrity of the E3 signal was restored properly over 0 to 12 dB cable
loss at Industrial Temperature.
The Equalizer also contain an additional 20 dB gain stage to provide the line monitoring capability of the
resistively attenuated signals which may have 20dB flat loss. This capability can be turned on by writing a “1” to
the RxMON_n bits in the control register or by setting the RxMON pin (pin 69) “High”.
6.1.1
Interference Tolerance:
For E3 mode, ITU-T G.703 Recommendation specifies that the receiver be able to recover error-free clock and
data in the presence of a sinusoidal interfering tone signal. For DS3 and STS-1 modes, the same
recommendation is being used. Figure 17 shows the configuration to test the interference margin for DS3/
STS1. Figure 18 shows the set up for E3.
FIGURE 18. INTERFERENCE MARGIN TEST SET UP FOR DS3/STS-1
Attenuator
Sine Wave
Generator
N
DS3 = 22.368 MHz
STS-1 = 25.92 MHz
0 to 900 feet
Coaxial Cable
∑
DUT
XRT75R03D
Test Equipment
Pattern Generator
2 23 -1 PRBS
S
45
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
FIGURE 19. INTERFERENCE MARGIN TEST SET UP FOR E3.
Attenuator 1
Noise Generator
Attenuator 2
N
Cable Simulator
∑
DUT
XRT75R03D
Test Equipment
Signal Source
2
23
S
-1 PRBS
TABLE 9: INTERFERENCE MARGIN TEST RESULTS
MODE
CABLE LENGTH (ATTENUATION)
INTERFERENCE TOLERANCE
Equalizer “IN”
E3
DS3
STS-1
6.2
-17 dB
0 dB
12 dB
-14 gB
0 feet
-15 dB
225 feet
-15 dB
450 feet
-14 dB
0 feet
-15 dB
225 feet
-14 dB
450 feet
-14 dB
Clock and Data Recovery:
The Clock and Data Recovery Circuit extracts the embedded clock, RxClk_n from the sliced digital data stream
and provides the retimed data to the B3ZS (HDB3) decoder.
The Clock Recovery PLL can be in one of the following two modes:
TRAINING MODE:
In the absence of input signals at RTIP_n and RRing_n pins, or when the frequency difference between the
recovered line clock signal and the reference clock applied on the ExClk_n input pins exceed 0.5%, a Loss of
Lock condition is declared by toggling RLOL_n output pin “High” (in Hardware Mode) or setting the RLOL_n bit
to “1” in the control registers (in Host Mode). Also, the clock output on the RxClk_n pins are the same as the
reference clock applied on ExClk_n pins.
DATA/CLOCK RECOVERY MODE:
In the presence of input line signals on the RTIP_n and RRing_n input pins and when the frequency difference
between the recovered clock signal and the reference clock signal is less than 0.5%, the clock that is output on
the RxClk_n out pins is the Recovered Clock signal.
46
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
B3ZS/HDB3 Decoder:
6.3
The decoder block takes the output from clock and data recovery block and decodes the B3ZS (for DS3 or
STS-1) or HDB3 (for E3) encoded line signal and detects any coding errors or excessive zeros in the data
stream.
Whenever the input signal violates the B3ZS or HDB3 coding sequence for bipolar violation or contains three
(for B3ZS) or four (for HDB3) or more consecutive zeros, an active “High” pulse is generated on the RLCV_n
output pins to indicate line code violation.
NOTE: In Dual-Rail mode, the decoder is bypassed.
LOS (Loss of Signal) Detector:
6.4
6.4.1
DS3/STS-1 LOS Condition:
A Digital Loss of SIgnal (DLOS) condition occurs when a string of 175 ± 75 consecutive zeros occur on the line.
When the DLOS condition occurs, the DLOS_n bit is set to “1” in the status control register. DLOS condition is
cleared when the detected average pulse density is greater than 33% for 175 ± 75 pulses.
Analog Loss of Signal (ALOS) condition occurs when the amplitude of the incoming line signal is below the
threshold as shown in the Table 10.The status of the ALOS condition is reflected in the ALOS_n status control
register.
RLOS is the logical OR of the DLOS and ALOS states. When the RLOS condition occurs the RLOS_n output
pin is toggled “High” and the RLOS_n bit is set to “1” in the status control register.
TABLE 10: THE ALOS (ANALOG LOS) DECLARATION AND CLEARANCE THRESHOLDS FOR A GIVEN SETTING OF
LOSTHR AND REQEN (DS3 AND STS-1 APPLICATIONS)
APPLICATION REQEN SETTING LOSTHR SETTING
DS3
STS-1
SIGNAL LEVEL TO DECLARE ALOS
DEFECT
SIGNAL LEVEL TO CLEAR ALOS
DEFECT
0
0
< 75mVpk
> 130mVpk
1
0
< 45mVpk
> 60mVpk
0
1
< 120mVpk
> 45mVpk
1
1
< 55mVpk
> 180mVpk
0
0
< 120mVpk
> 170mVpk
1
0
< 50mVpk
> 75mVpk
0
1
< 125mVpk
> 205mVpk
1
1
< 55mVpk
> 90mVpk
DISABLING ALOS/DLOS DETECTION:
For debugging purposes it is useful to disable the ALOS and/or DLOS detection. Writing a “1” to both
ALOSDIS_n and DLOSDIS_n bits disables the LOS detection on a per channel basis.
6.4.2
E3 LOS Condition:
If the level of incoming line signal drops below the threshold as described in the ITU-T G.775 standard, the
LOS condition is detected. Loss of signal level is defined to be between 15 and 35 dB below the normal level. If
the signal drops below 35 dB for 10 to 255 consecutive pulse periods, LOS condition is declared. This is
illustrated in Figure 19.
47
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
FIGURE 20. LOSS OF SIGNAL DEFINITION FOR E3 AS PER ITU-T G.775
0 dB
Maximum Cable Loss for E3
LOS Signal Must be Cleared
-12 dB
-15dB
LOS Signal may be Cleared or Declared
-35dB
LOS Signal Must be Declared
As defined in ITU-T G.775, an LOS condition is also declared between 10 and 255 UI (or E3 bit periods) after
the actual time the LOS condition has occurred. The LOS condition is cleared within 10 to 255 UI after
restoration of the incoming line signal. Figure 20 shows the LOS declaration and clearance conditions.
FIGURE 21. LOSS OF SIGNAL DEFINITION FOR E3 AS PER ITU-T G.775.
Actual Occurrence
of LOS Condition
Line Signal
is Restored
RTIP/
RRing
10 UI
255 UI
Time Range for
LOS Declaration
10 UI
255 UI
RLOS Output Pin
0 UI
0 UI
G.775
Compliance
Time Range for
LOS Clearance
48
G.775
Compliance
XRT75R03D
REV. 1.0.2
6.4.3
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
Muting the Recovered Data with LOS condition:
When the LOS condition is declared, the clock recovery circuit locks into the reference clock applied to the
ExClk_n pin and output this clock on the RxClk_n output.In Single Frequency Mode (SFM), the clock recovery
locks into the rate clock generated and output this clock on the RxClk_n pins. The data on the RPOS_n and
RNEG_n pins can be forced to zero by pulling the LOSMUT pin “High” (in Hardware Mode) or by setting the
LOSMUT_n bits in the individual channel control register to “1” (in Host Mode).
NOTE: When the LOS condition is cleared, the recovered data is output on RPOS_n and RNEG_n pins.
7.0 JITTER:
There are three fundamental parameters that describe circuit performance relative to jitter:
• Jitter Tolerance (Receiver)
• Jitter Transfer (Receiver/Transmitter)
• Jitter Generation
7.1
JITTER TOLERANCE - RECEIVER:
Jitter tolerance is a measure of how well a Clock and Data Recovery unit can successfully recover data in the
presence of various forms of jitter. It is characterized by the amount of jitter required to produce a specified bit
error rate. The tolerance depends on the frequency content of the jitter. Jitter Tolerance is measured as the
jitter amplitude over a jitter spectrum for which the clock and data recovery unit achieves a specified bit error
rate (BER). To measure the jitter tolerance as shown in Figure 21, jitter is introduced by the sinusoidal
modulation of the serial data bit sequence.
FIGURE 22. JITTER TOLERANCE MEASUREMENTS
Pattern
Generator
Data
Error
Detector
DUT
XRT75VL03D
Clock
Modulation
Freq.
FREQ
Synthesizer
Input jitter tolerance requirements are specified in terms of compliance with jitter mask which is represented as
a combination of points.Each point corresponds to a minimum amplitude of sinusoidal jitter at a given jitter
frequency.
7.1.1
DS3/STS-1 Jitter Tolerance Requirements:
Bellcore GR-499 CORE, Issue 1, December 1995 specifies the minimum requirement of jitter tolerance for
Category I and Category II. The jitter tolerance requirement for Category II is the most stringent. Figure 22
shows the jitter tolerance curve as per GR-499 specification.
49
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
JITTER AMPLITUDE (UI pp)
FIGURE 23. INPUT JITTER TOLERANCE FOR DS3/STS-1
64
GR-253 STS-1
41
15
GR-499 Cat II
GR-499 Cat I
10
XRT75VL03D
5
1.5
0.3
0.15
0.1
0.01
0.03
0.3
2
20
100
JITTER FREQUENCY (kHz)
7.1.2
E3 Jitter Tolerance Requirements:
ITU-T G.823 standard specifies that the clock and data recovery unit must be able to accommodate and
tolerate jitter up to certain specified limits. Figure 23 shows the tolerance curve.
FIGURE 24. INPUT JITTER TOLERANCE FOR E3
ITU-T G.823
JITTER AMPLITUDE (UIpp)
64
XRT75VL03D
10
1.5
0.3
0.1
1
10
800
JITTER FREQUENCY (kHz)
As shown in the Figures 22 and 23 above, in the jitter tolerance measurement, the dark line indicates the
minimum level of jitter that the E3/DS3/STS-1 compliant component must tolerate.
The Table 11 below shows the jitter amplitude versus the modulation frequency for various standards.
50
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE 11: JITTER AMPLITUDE VERSUS MODULATION FREQUENCY (JITTER TOLERANCE)
INPUT JITTER AMPLITUDE (UI P-P)
BIT RATE
(KB/S)
STANDARD
34368
MODULATION FREQUENCY
A1
A2
A3
F1(HZ)
F2(HZ)
F3(KHZ)
F4(KHZ)
F5(KHZ)
ITU-T G.823
1.5
0.15
-
100
1000
10
800
-
44736
GR-499
CORE Cat I
5
0.1
-
10
2.3k
60
300
-
44736
GR-499
CORE Cat II
10
0.3
-
10
669
22.3
300
-
51840
GR-253
CORE Cat II
15
1.5
0.15
10
30
300
2
20
7.2
JITTER TRANSFER - RECEIVER/TRANSMITTER:
Jitter Transfer function is defined as the ratio of jitter on the output relative to the jitter applied on the input
versus frequency.
There are two distinct characteristics in jitter transfer: jitter gain (jitter peaking) defined as the highest ratio
above 0dB; and jitter transfer bandwidth.The overall jitter transfer bandwidth is controlled by a low bandwidth
loop, typically using a voltage-controller crystal oscillator (VCXO).
The jitter transfer function is a ratio between the jitter output and jitter input for a component, or system often
expressed in dB. A negative dB jitter transfer indicates the element removed jitter. A positive dB jitter transfer
indicates the element added jitter.A zero dB jitter transfer indicates the element had no effect on jitter.
Table 12 shows the jitter transfer characteristics and/or jitter attenuation specifications for various data rates:
TABLE 12: JITTER TRANSFER SPECIFICATION/REFERENCES
E3
DS3
STS-1
ETSI TBR-24
GR-499 CORE section 7.3.2
Category I and Category II
GR-253 CORE section 5.6.2.1
The above specifications can be met only with a jitter attenuator that supports E3/DS3/STS-1 rates.
7.3
Jitter Attenuator:
An advanced crystal-less jitter attenuator per channel is included in the XRT75R03D. The jitter attenuator
requires no external crystal nor high-frequency reference clock.
In Host mode, by clearing or setting the JATx/Rx_n bits in the channel control registers selects the jitter
attenuator either in the Receive or Transmit path on per channel basis. In Hardware mode, JATx/Rx pin selects
globally all three channels either in Receive or Transmit path.
The FIFO size can be either 16-bit or 32-bit. In HOST mode, the bits JA0_n and JA1_n can be set to
appropriate combination to select the different FIFO sizes or to disable the Jitter Attenuator on a per channel
basis. In Hardware mode, appropriate setting of the pins JA0 and JA1 selects the different FIFO sizes or
disables the Jitter Attenuator for all three channels. Data is clocked into the FIFO with the associated clock
signal (TxClk or RxClk) and clocked out of the FIFO with the dejittered clock. When the FIFO is within two bits
of overflowing or underflowing, the FIFO limit status bit, FL_n is set to “1” in the Alarm status register. Reading
this bit clears the FIFO and resets the bit into default state.
NOTE: It is recommended to select the 16-bit FIFO for delay-sensitive applications as well as for removing smaller amounts
of jitter. Table 13 specifies the jitter transfer mask requirements for various data rates:
51
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 13: JITTER TRANSFER PASS MASKS
RATE
(KBITS)
MASK
F1
(HZ)
F2
(HZ)
F3
(HZ)
F4
(KHZ)
A1(dB)
A2(dB)
34368
G.823
ETSI-TBR-24
100
300
3K
800K
0.5
-19.5
44736
GR-499, Cat I
GR-499, Cat II
GR-253 CORE
10
10
10
10k
56.6k
40
-
15k
300k
15k
0.1
0.1
0.1
-
51840
GR-253 CORE
10
40k
-
400k
0.1
-
The jitter attenuator within the XRT75R03D meets the latest jitter attenuation specifications and/or jitter
transfer characteristics as shown in the Figure 24.
JITTER AMPLITUDE
FIGURE 25. JITTER TRANSFER REQUIREMENTS AND JITTER ATTENUATOR PERFORMANCE
A1
A2
F1
F2
F3
F4
J IT T E R F R E Q U E N C Y (k H z )
7.3.1
JITTER GENERATION:
Jitter Generation is defined as the process whereby jitter appears at the output port of the digital equipment in
the absence of applied input jitter. Jitter Generation is measured by sending jitter free data to the clock and
data recovery circuit and measuring the amount of jitter on the output clock or the re-timed data. Since this is
essentially a noise measurement, it requires a definition of bandwidth to be meaningful. The bandwidth is set
according to the data rate. In general, the jitter is measured over a band of frequencies.
8.0 SERIAL HOST INTERFACE:
A serial microprocessor interface is included in the XRT75R03D. The interface is generic and is designed to
support the common microprocessors/microcontrollers. The XRT75R03D operates in Host mode when the
HOST/HW pin is tied “High”. The serial interface includes a serial clock (SClk), serial data input (SDI), serial
data output (SDO), chip select (CS) and interrupt output (INT). The serial interface timing is shown in Figure
11.
The active low interrupt output signal (INT pin) indicates alarm conditions like LOS, DMO and FL to the
processor.
52
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
When the XRT75R03D is configured in Host mode, the following input pins,TxLEV_n, TAOS_n, RLB_n,
LLB_n, E3_n, STS-1/DS3_n, REQEN_n, JATx/Rx, JA0 and JA1 are disabled and must be connected to
ground.
The Table 14 below illustrates the functions of the shared pins in either Host mode or in Hardware mode.
TABLE 14: FUNCTIONS OF SHARED PINS
PIN NUMBER
IN HOST MODE
IN HARDWARE MODE
66
CS
RxClkINV
67
SClk
TxClkINV
68
SDI
RxON
69
SDO
RxMON
71
INT
LOSMUT
NOTE: While configured in Host mode, the TxON_n input pins will be active if the TxON_n bits in the control register are set
to “1”, and can be used to turn on and off the transmit output drivers. This permits a system designed for
redundancy to quickly switch out a defective line card and switch-in the backup line card.
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 15: XRT75R03D REGISTER MAP - QUICK LOOK
ADDRESS
LOCATION
0x00
REGISTER NAME
BIT 7
APS/Redundancy
Control Register
Reserved
BIT 6
BIT 5
BIT 4
RxON Ch 2 RxON Ch 1 RxON Ch 0
BIT 3
BIT 2
BIT 1
BIT 0
Reserved
TxON Ch 2 TxON Ch 1 TxON Ch 0
CHANNEL 0 REGISTERS
0x01
Source Level
Interrupt Enable
Register - Ch 0
Reserved
Change of
FL Alarm
Condition
Interrupt
Enable
Change of
RLOL
Condition
Interrupt
Enable
Change of
RLOS
Defect
Condition
Interrupt
Enable
Change of
DMO
Condition
Interrupt
Enable
0x02
Source Level
Interrupt Status
Register - Ch 0
Reserved
Change of
FL Alarm
Condition
Interrupt
Status
Change of
RLOL
Condition
Interrupt
Status
Change of
RLOS
Condition
Interrupt
Status
Change of
DMO
Condition
Interrupt
Status
0x03
Alarm Status
Register - Ch 0
0x04
Transmit Control
Register - Ch 0
0x05
DLOS
Defect
Declared
ALOS
Defect
Declared
FL Alarm
Declared
RLOL
Condition
Declared
RLOS
Defect
Condition
DMO
Condition
Status
Reserved
Internal
Transmit
Drive
Monitoring
Insert
PRBS
Error
Unused
TAOS
TxCLK INV
TxLEV
Receive Control
Register - Ch 0
Reserved
DisableDLOS
Detector
DisableALOS Detector
RxCLK
INV
LOSMUTEnable
Receive
Monitor
Mode
Enable
Receive
Equalizer
Enable
0x06
Channel Control
Register - Ch 0
Reserved
PRBS
Enable
RLB
LLB
E3 Mode
STS-1/DS3
Mode
SR/DR
Mode
0x07
Jitter Attenuator
Control Register Ch 0
SONET
APS
Recovery
Time Mode
Disable
JA
RESET
JA1
(JA Mode
Select Bit 1)
JA in
TxPath
JA0
(JA Mode
Select 0)
Reserved
Reserved
Reserved
Reserved
Reserved
Loss of
PRBS
Pattern Sync
Reserved
CHANNEL 1 REGISTERS
0x08
Reserved
Reserved
0x09
Source Level
Interrupt Enable
Register - Ch 0
Reserved
Change of
FL Alarm
Condition
Interrupt
Enable
Change of
RLOL
Condition
Interrupt
Enable
Change of
RLOS
Defect
Condition
Interrupt
Enable
Change of
DMO
Condition
Interrupt
Enable
0x0A
Source Level
Interrupt Status
Register - Ch 0
Reserved
Change of
FL Alarm
Condition
Interrupt
Status
Change of
RLOL
Condition
Interrupt
Status
Change of
RLOS
Condition
Interrupt
Status
Change of
DMO
Condition
Interrupt
Status
54
Reserved
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE 15: XRT75R03D REGISTER MAP - QUICK LOOK
ADDRESS
LOCATION
REGISTER NAME
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
0x0B
Alarm Status
Register - Ch 0
Reserved
Loss of
PRBS
Pattern Sync
DLOS
Defect
Declared
ALOS
Defect
Declared
FL Alarm
Declared
RLOL
Condition
Declared
RLOS
Defect
Condition
DMO
Condition
Status
0x0C
Transmit Control
Register - Ch 0
Reserved
Internal
Transmit
Drive
Monitoring
Insert
PRBS
Error
Unused
TAOS
TxCLK INV
TxLEV
0x0D
Receive Control
Register - Ch 0
Reserved
DisableDLOS
Detector
DisableALOS Detector
RxCLK
INV
LOSMUTEnable
Receive
Monitor
Mode
Enable
Receive
Equalizer
Enable
0x0E
Channel Control
Register - Ch 0
Reserved
PRBS
Enable
RLB
LLB
E3 Mode
STS-1/DS3
Mode
SR/DR
Mode
0x0F
Jitter Attenuator
Control Register Ch 0
SONET
APS
Recovery
Time Mode
Disable
JA
RESET
JA1
(JA Mode
Select Bit 1)
JA in
TxPath
JA0
(JA Mode
Select 0)
Reserved
Reserved
Reserved
Reserved
Reserved
CHANNEL 2 REGISTERS
0x10
Reserved
Reserved
0x11
Source Level
Interrupt Enable
Register - Ch 0
Reserved
Change of
FL Alarm
Condition
Interrupt
Enable
Change of
RLOL
Condition
Interrupt
Enable
Change of
RLOS
Defect
Condition
Interrupt
Enable
Change of
DMO
Condition
Interrupt
Enable
0x12
Source Level
Interrupt Status
Register - Ch 0
Reserved
Change of
FL Alarm
Condition
Interrupt
Status
Change of
RLOL
Condition
Interrupt
Status
Change of
RLOS
Condition
Interrupt
Status
Change of
DMO
Condition
Interrupt
Status
0x13
Alarm Status
Register - Ch 0
0x14
Transmit Control
Register - Ch 0
0x15
0x16
DLOS
Defect
Declared
ALOS
Defect
Declared
FL Alarm
Declared
RLOL
Condition
Declared
RLOS
Defect
Condition
DMO
Condition
Status
Reserved
Internal
Transmit
Drive
Monitoring
Insert
PRBS
Error
Unused
TAOS
TxCLK INV
TxLEV
Receive Control
Register - Ch 0
Reserved
DisableDLOS
Detector
DisableALOS Detector
RxCLK
INV
LOSMUTEnable
Receive
Monitor
Mode
Enable
Receive
Equalizer
Enable
Channel Control
Register - Ch 0
Reserved
PRBS
Enable
RLB
LLB
E3 Mode
STS-1/DS3
Mode
SR/DR
Mode
Reserved
Loss of
PRBS
Pattern Sync
Reserved
55
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 15: XRT75R03D REGISTER MAP - QUICK LOOK
ADDRESS
LOCATION
REGISTER NAME
BIT 7
BIT 6
BIT 5
Reserved
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SONET
APS
Recovery
Time Mode
Disable
JA
RESET
JA1
(JA Mode
Select Bit 1)
JA in
TxPath
JA0
(JA Mode
Select 0)
0
1
1
0x17
Jitter Attenuator
Control Register Ch 0
0x19 0x1F
Reserved
0x20
Block Level
Interrupt Enable
Register - Ch 32
0x21
Block Level
Interrupt Status
Register - Ch 33
0x22 0x3D
Reserved
0x3E
Device Part
Number Register
0
1
1
1
0x3F
Chip Revision
Number Register
0
0
0
0
0x40 0xFF
Reserved
Reserved
Reserved
0
Revision Number Value
Reserved
LEGEND:
Denotes Reserved (or Unused) Register Bits
Denotes Read/Write Bits
Denotes Read-Only Bits
Denotes Reset-Upon-Read Bits
THE REGISTER MAP AND DESCRIPTION FOR THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU IC
TABLE 16: COMMAND REGISTER ADDRESS MAP, WITHIN THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU W/
JITTER ATTENUATOR IC
ADDRESS
COMMAND REGISTER
TYPE
0x00
CR0
R/W
REGISTER NAME
APS/Redundancy Control Register
CHANNEL 0 CONTROL REGISTERS
0x01
CR1
R/O
Source Level Interrupt Enable Register - Channel
0
0x02
CR2
R/W
Source Level Interrupt Status Register Channel 0
0x03
CR3
R/O
Alarm Status Register - Channel 0
56
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE 16: COMMAND REGISTER ADDRESS MAP, WITHIN THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU W/
JITTER ATTENUATOR IC
ADDRESS
COMMAND REGISTER
TYPE
REGISTER NAME
0x04
CR4
R/W
Transmit Control Register - Channel 0
0x05
CR5
R/W
Receive Control Register - Channel 0
0x06
CR6
R/W
Channel Control Register - Channel 0
0x07
CR7
R/W
Jitter Attenuator Control Register - Channel 0
CHANNEL 1 CONTROL REGISTERS
0x08
CR8
R/O
Reserved
0x09
CR9
R/W
Source Level Interrupt Enable Register - Channel
1
0x0A
CR10
RUR
Source Level Interrupt Status Register - Channel 1
0x0B
CR11
R/O
Alarm Status Register - Channel 1
0x0C
CR12
R/W
Transmit Control Register - Channel 1
0x0D
CR13
R/W
Receive Control Register - Channel 1
0x0E
CR14
R/W
Channel Control Register - Channel 1
0x0F
CR15
R/W
Jitter Attenuator Control Register - Channel 1
CHANNEL 2 CONTROL REGISTERS
0x10
CR16
R/W
Reserved
0x11
CR17
R/W
Source Level Interrupt Enable Register - Channel
2
0x12
CR18
RUR
Source Level Interrupt Status Register - Channel 2
0x13
CR19
R/O
Alarm Status Register - Channel 2
0x14
CR20
R/W
Transmit Control Register - Channel 2
0x15
CR21
R/W
Receive Control Register - Channel 2
0x16
CR22
R/W
Channel Control Register - Channel 2
0x17
CR23
R/W
Jitter Attenuator Control Register - Channel 2
0x18 - 0x1F
Reserved
BLOCK LEVEL INTERRUPT ENABLE/STATUS REGISTERS (CHANNELS 0 - 2)
0x20
CR32
R/W
Block Level Interrupt Enable Register
0x21
CR33
R/O
Block Level Interrupt Status Register
0x22 - 0x3D
Reserved
Reserved
DEVICE IDENTIFICATION REGISTERS
0x3E
CR62
R/O
Device Part Number Register
0x3F
CR63
R/O
Chip Revision Number Register
57
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
THE GLOBAL/CHIP-LEVEL REGISTERS
The register set, within the XRT75R03D consists of five "Global" or "Chip-Level" Registers and 21 per-Channel
Registers. This section will present detailed information on the Global Registers.
TABLE 17: LIST AND ADDRESS LOCATIONS OF GLOBAL REGISTERS
ADDRESS
COMMAND REGISTER
TYPE
REGISTER NAME
0x00
CR0
R/W
APS/Redundancy Control Register
0x01 - 0x1F
Bank of Per-Channel Registers
0x20
CR32
R/W
Block Level Interrupt Enable Register
0x21
CR33
R/O
Block Level Interrupt Status Register
0x22 - 0x3D
Reserved Registers
0x3E
CR62
R/O
Device/Part Number Register
0x3F
CR63
R/O
Chip Revision Number Register
REGISTER DESCRIPTION - GLOBAL REGISTERS
TABLE 18: APS/REDUNDANCY CONTROL REGISTER - CR0 (ADDRESS LOCATION = 0X00)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Reserved
RxONCh 2
RxON Ch 1
RxON Ch 0
Reserved
TxON Ch 2
TxON Ch 1
TxON Ch 0
R/O
R/W
R/W
R/W
R/O
R/W
R/W
R/W
0
0
0
0
0
0
0
0
DEFAULT
VALUE
BIT
NUMBER
NAME
TYPE
7
Reserved
R/O
0
6
RxON Ch 2
R/W
0
DESCRIPTION
Receiver Section ON - Channel 2
This READ/WRITE bit-field is used to either turn on or turn off the
Receive Section of Channel 2. If the user turns on the Receive Section, then Channel 2 will begin to receive the incoming DS3, E3 or
STS-1 data-stream via the RTIP_2 and RRING_2 input pins.
Conversely, if the user turns off the Receive Section, then the entire
Receive Section (e.g., AGC and Receive Equalizer Block, Clock
Recovery PLL, etc) will be powered down.
0 - Shuts off the Receive Section of Channel 2.
1 - Turns on the Receive Section of Channel 2.
58
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT
NUMBER
NAME
TYPE
DEFAULT
VALUE
5
RxON Ch 1
R/W
0
Receiver Section ON - Channel 1
This READ/WRITE bit-field is used to either turn on or turn off the
Receive Section of Channel 1. If the user turns on the Receive Section, then Channel 1 will begin to receive the incoming DS3, E3 or
STS-1 data-stream via the RTIP_1 and RRING_1 input pins.
Conversely, if the user turns off the Receive Section, then the entire
Receive Section (e.g., AGC and Receive Equalizer Block, Clock
Recovery PLL, etc) will be powered down.
0 - Shuts off the Receive Section of Channel 1.
1 - Turns on the Receive Section of Channel 1.
4
RxON Ch 0
R/W
0
Receiver Section ON - Channel 0
This READ/WRITE bit-field is used to either turn on or turn off the
Receive Section of Channel 0. If the user turns on the Receive Section, then Channel 0 will begin to receive the incoming DS3, E3 or
STS-1 data-stream via the RTIP_0 and RRING_0 input pins.
Conversely, if the user turns off the Receive Section, then the entire
Receive Section (e.g., AGC and Receive Equalizer Block, Clock
Recovery PLL, etc) will be powered down.
0 - Shuts off the Receive Section of Channel 0.
1 - Turns on the Receive Section of Channel 0.
3
Reserved
R/O
0
2
TxON Ch 2
R/W
0
DESCRIPTION
Transmit Driver ON - Channel 2
This READ/WRITE bit-field is used to either turn on or turn off the
Transmit Driver associated with Channel 2. If the user turns on the
Transmit Driver, then Channel 2 will begin to transmit DS3, E3 or
STS-1 pulses on the line via the TTIP_2 and TRING_ 2 output pins.
Conversely, if the user turns off the Transmit Driver, then the TTIP_2
and TRING_2 output pins will be tri-stated.
0 - Shuts off the Transmit Driver associated with Channel 2 and tristates the TTIP_2 and TRING_ 2 output pins.
1 - Turns on or enables the Transmit Driver associated with Channel
2.
NOTE: If the user wishes to exercise software control over the state
of the Transmit Driver associated with Channel 2, then it is
imperative that the user pull the TxON_2 (pin 125) to a logic
"High" level.
59
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT
NUMBER
NAME
TYPE
1
TxON Ch 1
R/W
DEFAULT
VALUE
0
REV. 1.0.2
DESCRIPTION
Transmit Section ON - Channel 1
This READ/WRITE bit-field is used to either turn on or turn off the
Transmit Driver associated with Channel 1. If the user turns on the
Transmit Driver, then Channel 1 will begin to transmit DS3, E3 or
STS-1 pulses on the line via the TTIP_1 and TRING_ 1 output pins.
Conversely, if the user turns off the Transmit Driver, then the TTIP_1
and TRING_1 output pins will be tri-stated.
0 - Shuts off the Transmit Driver associated with Channel 1 and tristates the TTIP_1 and TRING_ 1 output pins.
1 - Turns on or enables the Transmit Driver associated with Channel
1.
NOTE: If the user wishes to exercise software control over the state
of the Transmit Driver associated with Channel 1, then it is
imperative that the user pull the TxON_1 (pin 1) to a logic
"High" level.
0
TxON Ch 0
R/W
0
Transmit Section ON - Channel 0
This READ/WRITE bit-field is used to either turn on or turn off the
Transmit Driver associated with Channel 0. If the user turns on the
Transmit Driver, then Channel 0 will begin to transmit DS3, E3 or
STS-1 pulses on the line via the TTIP_0 and TRING_ 0 output pins.
Conversely, if the user turns off the Transmit Driver, then the TTIP_0
and TRING_0 output pins will be tri-stated.
0 - Shuts off the Transmit Driver associated with Channel 0 and tristates the TTIP_0 and TRING_ 0 output pins.
1 - Turns on or enables the Transmit Driver associated with Channel
0.
NOTE: If the user wishes to exercise software control over the state
of the Transmit Driver associated with Channel 0, then it is
imperative that the user pull the TxON_0 (pin 38) to a logic
"High" level.
60
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE 19: BLOCK LEVEL INTERRUPT ENABLE REGISTER - CR32 (ADDRESS LOCATION = 0X20)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Reserved
BIT 2
BIT 1
BIT 0
Channel 2
Interrupt
Enable
Channel 1
Interrupt
Enable
Channel 0
Interrupt
Enable
R/O
R/O
R/O
R/O
R/O
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT
NUMBER
NAME
TYPE
DEFAULT
VALUE
7-3
Unused
R/O
0
2
Channel 2 Interrupt Enable
R/W
0
DESCRIPTION
Channel 2 Interrupt Enable Bit:
This READ/WRITE bit-field is used to do either of the following
• To enable Channel 2 for Interrupt Generation at the Block
Level
• To disable all Interrupts associated with Channel 2 within the
XRT75R03D
If the user enables Channel 2-related Interrupts at the Block
Level, then this means that a given Channel 2-related interrupt
(e.g., Change in LOS Defect Condition - Channel 2) will be
enabled if the user has also enabled this particular interrupt at
the Source Level.
If the user disables Channel 2-related Interrupts at the Block
Level, then this means that the XRT75R03D will NOT generate
any Channel 2-Related Interrupts at all.
0 - Disables all Channel 2-related Interrupt.
1 - Enables Channel 2-related Interrupts at the Block Level. The
user must still enable individual Channel 2-related Interrupts at
the source level, before they are enabled for interrupt generation.
1
Channel 1 Interrupt Enable
R/W
0
Channel 1 Interrupt Enable Bit:
Please see the description for Bit 2 Channel 2 Interrupt Enable.
0
Channel 0 Interrupt Enable
R/W
0
Channel 0 Interrupt Enable Bit:
Please see the description for Bit 2 Channel 2 Interrupt Enable.
61
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 20: BLOCK LEVEL INTERRUPT STATUS REGISTER - CR33 (ADDRESS LOCATION = 0X21)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Reserved
BIT 2
BIT 1
BIT 0
Channel 2
Channel 1
Channel 0
Interrupt Status Interrupt Status Interrupt Status
R/O
R/O
R/O
R/O
R/O
R/O
R/O
R/O
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-3
Unused
R/O
0
2
Channel
2 Interrupt Status
R/O
0
DESCRIPTION
Channel 2 Interrupt Status Bit:
This READ-ONLY bit-field indicates whether or not the XRT75R03D
has a pending Channel 2-related interrupt that is awaiting service.
0 - Indicates that there is NO Channel 2-related Interrupt awaiting
service.
1 - Indicates that there is at least one Channel 2-related Interrupt
awaiting service. In this case, the user’s Interrupt Service routine
should be written such that the Microprocessor will now proceed to
read out the contents of the Source Level Interrupt Status Register Channel 2 (Address Location = 0x12) in order to determine the
exact cause of the interrupt request.
NOTE: Once this bit-field is set to "1", it will not be cleared back to
"0" until the user has read out the contents of the SourceLevel Interrupt Status Register bit, that corresponds with
the interrupt request.
62
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
1
Channel
1 Interrupt
Status
R/W
0
DESCRIPTION
Channel 1 Interrupt Enable Bit:
This READ-ONLY bit-field indicates whether or not the XRT75R03D
has a pending Channel 1-related interrupt that is awaiting service.
0 - Indicates that there is NO Channel 1-related Interrupt awaiting
service.
1 - Indicates that there is at least one Channel 1-related Interrupt
awaiting service. In this case, the user’s Interrupt Service routine
should be written such that the Microprocessor will now proceed to
read out the contents of the Source Level Interrupt Status Register Channel 1 (Address Location = 0x0A) in order to determine the
exact cause of the interrupt request.
NOTE: Once this bit-field is set to "1", it will not be cleared back to
"0" until the user has read out the contents of the SourceLevel Interrupt Status Register bit, that corresponds with
the interrupt request.
0
Channel
0 Interrupt
Status
R/W
0
Channel 0 Interrupt Enable Bit:
This READ-ONLY bit-field indicates whether or not the XRT75R03D
has a pending Channel 0-related interrupt that is awaiting service.
0 - Indicates that there is NO Channel 0-related Interrupt awaiting
service.
1 - Indicates that there is at least one Channel 0-related Interrupt
awaiting service. In this case, the user’s Interrupt Service routine
should be written such that the Microprocessor will now proceed to
read out the contents of the Source Level Interrupt Status Register Channel 0 (Address Location = 0x02) in order to determine the
exact cause of the interrupt request.
NOTE: Once this bit-field is set to "1", it will not be cleared back to
"0" until the user has read out the contents of the SourceLevel Interrupt Status Register bit, that corresponds with
the interrupt request.
TABLE 21: DEVICE/PART NUMBER REGISTER - CR62 (ADDRESS LOCATION = 0X3E)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Part Number ID Value
R/O
R/O
R/O
R/O
R/O
R/O
R/O
R/O
0
1
1
1
0
0
1
1
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-0
Part Number ID
Value
R/O
0x73
DESCRIPTION
Part Number ID Value:
This READ-ONLY register contains a unique value that
represents the XRT75R03D. In the case of the
XRT75R03D, this value will always be 0x73.
63
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 22: CHIP REVISION NUMBER REGISTER - CR63 (ADDRESS LOCATION = 0X3F)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Chip Revision Number Value
R/O
R/O
R/O
R/O
R/O
R/O
R/O
R/O
1
0
0
0
X
X
X
X
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-0
Chip Revision
Number Value
R/O
0x0#
DESCRIPTION
Chip Revision Number Value:
This READ-ONLY register contains a value that represents
the current revision of this XRT75R03D. This revision
number will always be in the form of "0x0#", where "#" is a
hexadecimal value that specifies the current revision of the
chip.
For example, the very first revision of this chip will contain
the value "0x01".
THE PER-CHANNEL REGISTERS
The XRT75R03D consists of 21 per-Channel Registers. Table 23 presents the overall Register Map with the
Per-Channel Registers shaded.
TABLE 23: COMMAND REGISTER ADDRESS MAP, WITHIN THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU W/
JITTER ATTENUATOR IC
ADDRESS
COMMAND REGISTER
TYPE
0x00
CR0
R/W
REGISTER NAME
APS/Redundancy Control Register
CHANNEL 0 CONTROL REGISTERS
0x01
CR1
R/O
Source Level Interrupt Enable Register - Channel 0
0x02
CR2
R/W
Source Level Interrupt Status Register Channel 0
0x03
CR3
R/O
Alarm Status Register - Channel 0
0x04
CR4
R/W
Transmit Control Register - Channel 0
0x05
CR5
R/W
Receive Control Register - Channel 0
0x06
CR6
R/W
Channel Control Register - Channel 0
0x07
CR7
R/W
Jitter Attenuator Control Register - Channel 0
CHANNEL 1 CONTROL REGISTERS
0x08
CR8
R/O
Reserved
0x09
CR9
R/W
Source Level Interrupt Enable Register - Channel 1
0x0A
CR10
RUR
Source Level Interrupt Status Register - Channel 1
0x0B
CR11
R/O
Alarm Status Register - Channel 1
0x0C
CR12
R/W
Transmit Control Register - Channel 1
64
XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
TABLE 23: COMMAND REGISTER ADDRESS MAP, WITHIN THE XRT75R03D 3-CHANNEL DS3/E3/STS-1 LIU W/
JITTER ATTENUATOR IC
ADDRESS
COMMAND REGISTER
TYPE
REGISTER NAME
0x0D
CR13
R/W
Receive Control Register - Channel 1
0x0E
CR14
R/W
Channel Control Register - Channel 1
0x0F
CR15
R/W
Jitter Attenuator Control Register - Channel 1
CHANNEL 2 CONTROL REGISTERS
0x10
CR16
R/W
Reserved
0x11
CR17
R/W
Source Level Interrupt Enable Register - Channel 2
0x12
CR18
RUR
Source Level Interrupt Status Register - Channel 2
0x13
CR19
R/O
Alarm Status Register - Channel 2
0x14
CR20
R/W
Transmit Control Register - Channel 2
0x15
CR21
R/W
Receive Control Register - Channel 2
0x16
CR22
R/W
Channel Control Register - Channel 2
0x17
CR23
R/W
Jitter Attenuator Control Register - Channel 2
0x18 - 0x1F
Reserved
BLOCK LEVEL INTERRUPT ENABLE/STATUS REGISTERS (CHANNELS 0 - 2)
0x20
CR32
R/W
Block Level Interrupt Enable Register
0x21
CR33
R/O
Block Level Interrupt Status Register
0x22 - 0x3D
Reserved
Reserved
DEVICE IDENTIFICATION REGISTERS
0x3E
CR62
R/O
Device Part Number Register
0x3F
CR63
R/O
Chip Revision Number Register
65
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
REGISTER DESCRIPTION - PER CHANNEL REGISTERS
TABLE 24: SOURCE LEVEL INTERRUPT ENABLE REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X01
Channel 1 Address Location = 0x09
Channel 2 Address Location = 0x11)
BIT 7
BIT 6
BIT 5
BIT 4
Unused
BIT 3
BIT 2
BIT 1
BIT 0
Change of FL Change of LOL Change of LOS
Change of
Condition
Condition
Condition
DMO Condition
Interrupt Enable Interrupt Enable Interrupt Enable Interrupt Enable
Ch 0
Ch 0
Ch 0
Ch 0
R/O
R/O
R/O
R/O
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-4
Reserved
R/O
0
3
Change of FL
Condition Interrupt
Enable - Ch 0
R/W
0
DESCRIPTION
Change of FL (FIFO Limit Alarm) Condition Interrupt
Enable - Ch 0:
This READ/WRITE bit-field is used to either enable or disable the Change of FL Condition Interrupt. If the user
enables this interrupt, then the XRT75R03D will generate
an interrupt any time any of the following events occur.
• Whenever the Jitter Attenuator (within Channel 0)
declares the FL (FIFO Limit Alarm) condition.
• Whenever the Jitter Attenuator (within Channel 0) clears
the FL (FIFO Limit Alarm) condition.
0 - Disables the Change in FL Condition Interrupt.
1 - Enables the Change in FL Condition Interrupt.
2
Change of LOL
Condition Interrupt
Enable
R/W
0
Change of Receive LOL (Loss of Lock) Condition Interrupt Enable - Channel 0:
This READ/WRITE bit-field is used to either enable or disable the Change of Receive LOL Condition Interrupt. If the
user enables this interrupt, then the XRT75R03D will generate an interrupt any time any of the following events
occur.
• Whenever the Receive Section (within Channel 0)
declares the Loss of Lock Condition.
• Whenever the Receive Section (within Channel 0) clears
the Loss of Lock Condition.
0 - Disables the Change in Receive LOL Condition Interrupt.
1 - Enables the Change in Receive LOL Condition Interrupt.
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
1
Change of LOS
Condition Interrupt
Enable
R/W
0
DESCRIPTION
Change of the Receive LOS (Loss of Signal) Defect
Condition Interrupt Enable - Ch 0:
This READ/WRITE bit-field is used to either enable or disable the Change of the Receive LOS Defect Condition
Interrupt. If the user enables this interrupt, then the
XRT75R03D will generate an interrupt any time any of the
following events occur.
• Whenever the Receive Section (within Channel 0)
declares the LOS Defect Condition.
• Whenever the Receive Section (within Channel 0) clears
the LOS Defect condition.
0 - Disables the Change in the LOS Defect Condition Interrupt.
1 - Enables the Change in the LOS Defect Condition Interrupt.
0
Change of DMO
Condition Interrupt
Enable
R/W
0
Change of Transmit DMO (Drive Monitor Output) Condition Interrupt Enable - Ch 0:
This READ/WRITE bit-field is used to either enable or disable the Change of Transmit DMO Condition Interrupt. If
the user enables this interrupt, then the XRT75R03D will
generate an interrupt any time any of the following events
occur.
• Whenever the Transmit Section toggles the DMO output
pin (or bit-field) to "1".
• Whenever the Transmit Section toggles the DMO output
pin (or bit-field) to "0".
0 - Disables the Change in the DMO Condition Interrupt.
1 - Enables the Change in the DMO Condition Interrupt.
67
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 25: SOURCE LEVEL INTERRUPT STATUS REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X02
Channel 1 Address Location = 0x0A
Channel 2 Address Location = 0x12
BIT 7
BIT 6
BIT 5
BIT 4
Unused
BIT 3
BIT 2
BIT 1
BIT 0
Change of FL Change of LOL Change of LOS Change of DMO
Condition
Condition
Condition
Condition
Interrupt Status Interrupt Status nterrupt Status Interrupt Status
Ch_n
Ch_n
Ch_n
Ch_n
R/O
R/O
R/O
R/O
RUR
RUR
RUR
RUR
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-4
Unused
R/O
0
3
Change of FL Condition Interrupt Status
RUR
0
DESCRIPTION
Change of FL (FIFO Limit Alarm) Condition Interrupt
Status - Ch 0:
This RESET-upon-READ bit-field indicates whether or not
the Change of FL Condition Interrupt (for Channel 0) has
occurred since the last read of this register.
0 - Indicates that the Change of FL Condition Interrupt has
NOT occurred since the last read of this register.
1 - Indicates that the Change of FL Condition Interrupt has
occurred since the last read of this register.
NOTE: The user can determine the current state of the
FIFO Alarm condition by reading out the contents
of Bit 3 (FL Alarm Declared) within the Alarm
Status Register.
2
Change of LOL
Condition Interrupt
Status
RUR
0
Change of Receive LOL (Loss of Lock) Condition Interrupt Status - Ch 0:
This RESET-upon-READ bit-field indicates whether or not
the Change of Receive LOL Condition Interrupt (for Channel 0) has occurred since the last read of this register.
0 - Indicates that the Change of Receive LOL Condition
Interrupt has NOT occurred since the last read of this register.
1 - Indicates that the Change of Receive LOL Condition
Interrupt has occurred since the last read of this register.
NOTE: The user can determine the current state of the
Receive LOL Defect condition by reading out the
contents of Bit 2 (Receive LOL Defect Declared)
within the Alarm Status Register.
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
1
Change of LOS
Condition Interrupt
Status
RUR
0
DESCRIPTION
Change of Receive LOS (Loss of Signal) Defect Condition Interrupt Status:
This RESET-upon-READ bit-field indicates whether or not
the Change of the Receive LOS Defect Condition Interrupt
(for Channel 0) has occurred since the last read of this register.
0 - Indicates that the Change of the Receive LOS Defect
Condition Interrupt has NOT occurred since the last read of
this register.
1 - Indicates that the Change of the Receive LOS Defect
Condition Interrupt has occurred since the last read of this
register.
NOTE: The user can determine the current state of the
Receive LOS Defect condition by reading out the
contents of Bit 1 (Receive LOS Defect Declared)
within the Alarm Status Register.
0
Change of DMO
Condition Interrupt
Status
RUR
0
Change of Transmit DMO (Drive Monitor Output) Condition Interrupt Status - Ch 0:
This RESET-upon-READ bit-field indicates whether or not
the Change of the Transmit DMO Condition Interrupt (for
Channel 0) has occurred since the last read of this register.
0 - Indicates that the Change of the Transmit DMO Condition Interrupt has NOT occurred since the last read of this
register.
1 - Indicates that the Change of the Transmit DMO Condition Interrupt has occurred since the last read of this register.
NOTE: The user can determine the current state of the
Transmit DMO Condition by reading out the
contents of Bit 0 (Transmit DMO Condition) within
the Alarm Status Register.
69
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 26: ALARM STATUS REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X03
Channel 1 Address Location = 0x0B
Channel 2 Address Location = 0x13
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Unused
Loss of PRBS
Pattern Sync
Digital LOS
Defect
Declared
Analog LOS
Defect
Declared
FL
(FIFO Limit)
Alarm
Declared
R/O
R/O
R/O
R/O
R/O
R/O
R/O
R/O
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7
Unused
R/O
0
6
Loss of PRBS Pattern Lock
R/O
0
BIT 2
BIT 1
Receive LOL Receive LOS
Defect
Defect
Declared
Declared
BIT 0
Transmit
DMO
Condition
DESCRIPTION
Loss of PRBS Pattern Lock Indicator:
This READ-ONLY bit-field indicates whether or not the
PRBS Receiver (within the Receive Section of Channel 0)
is declaring PRBS Lock within the incoming PRBS pattern.
If the PRBS Receiver detects a very large number of biterrors within its incoming data-stream, then it will declare
the Loss of PRBS Lock Condition.
Conversely, if the PRBS Receiver were to detect its predetermined PRBS pattern with the incoming DS3, E3 or
STS-1 data-stream, (with little or no bit errors) then the
PRBS Receiver will clear the Loss of PRBS Lock condition.
0 - Indicates that the PRBS Receiver is currently declaring
the PRBS Lock condition within the incoming DS3, E3 or
STS-1 data-stream.
1 - Indicates that the PRBS Receiver is currently declaring
the Loss of PRBS Lock condition within the incoming DS3,
E3 or STs-1 data-stream.
NOTE: This register bit is only valid if all of the following are
true.
a. The PRBS Generator block (within the Transmit
Section of the Chip is enabled).
b. The PRBS Receiver is enabled.
c. The PRBS Pattern (that is generated by the PRBS
Generator) is somehow looped back into the
Receive Path (via the Line-Side) and in-turn routed
to the receive input of the PRBS Receiver.
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
5
Digital LOS Defect
Declared
R/O
0
DESCRIPTION
Digital LOS Defect Declared:
This READ-ONLY bit-field indicates whether or not the Digital LOS (Loss of Signal) detector is declaring the LOS
Defect condition.
For DS3 and STS-1 applications, the Digital LOS Detector
will declare the LOS Defect condition whenever it detects
an absence of pulses (within the incoming DS3 or STS-1
data-stream) for 160 consecutive bit-periods.
Further, (again for DS3 and STS-1 applications) the Digital
LOS Detector will clear the LOS Defect condition whenever
it determines that the pulse density (within the incoming
DS3 or STS-1 signal) is at least 33%.
0 - Indicates that the Digital LOS Detector is NOT declaring
the LOS Defect Condition.
1 - Indicates that the Digital LOS Detector is currently
declaring the LOS Defect condition.
NOTES:
1. LOS Detection (within each channel of the
XRT75R03D) is performed by both an Analog
LOS Detector and a Digital LOS Detector. The
LOS state of a given Channel is simply a WIREDOR of the LOS Defect Declare states of these two
detectors.
2. The current LOS Defect Condition (for the
channel) can be determined by reading out the
contents of Bit 1 (Receive LOS Defect Declared)
within this register.
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
4
Analog LOS Defect
Declared
R/O
0
REV. 1.0.2
DESCRIPTION
Analog LOS Defect Declared:
This READ-ONLY bit-field indicates whether or not the
Analog LOS (Loss of Signal) detector is declaring the LOS
Defect condition.
For DS3 and STS-1 applications, the Analog LOS Detector
will declare the LOS Defect condition whenever it determines that the amplitude of the pulses (within the incoming
DS3/STS-1 line signal) drops below a certain Analog LOS
Defect Declaration threshold level.
Conversely, (again for DS3 and STS-1 applications) the
Analog LOS Detector will clear the LOS Defect condition
whenever it determines that the amplitude of the pulses
(within the incoming DS3/STS-1 line signal) has risen
above a certain Analog LOS Defect Clearance threshold
level.
It should be noted that, in order to prevent "chattering"
within the Analog LOS Detector output, there is some builtin hysteresis between the Analog LOS Defect Declaration
and the Analog LOS Defect Clearance threshold levels.
0 - Indicates that the Analog LOS Detector is NOT declaring the LOS Defect Condition.
1 - Indicates that the Analog LOS Detector is currently
declaring the LOS Defect condition.
NOTES:
1. LOS Detection (within each channel of the
XRT75R03D) is performed by both an Analog
LOS Detector and a Digital LOS Detector. The
LOS state of a given Channel is simply a WIREDOR of the LOS Defect Declare states of these two
detectors.
2. The current LOS Defect Condition (for the
channel) can be determined by reading out the
contents of Bit 1 (Receive LOS Defect Declared)
within this register.
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
3
FL Alarm Declared
R/O
0
DESCRIPTION
FL (FIFO Limit) Alarm Declared:
This READ-ONLY bit-field indicates whether or not the Jitter Attenuator block (within Channel_n) is currently declaring the FIFO Limit Alarm.
The Jitter Attenuator block will declare the FIFO Limit
Alarm anytime the Jitter Attenuator FIFO comes within two
bit-periods of either overflowing or under-running.
Conversely, the Jitter Attenuator block will clear the FIFO
Limit Alarm anytime the Jitter Attenuator FIFO is NO
longer within two bit-periods of either overflowing or underrunning.
Typically, this Alarm will only be declared whenever there is
a very serious problem with timing or jitter in the system.
0 - Indicates that the Jitter Attenuator block (within
Channel_n) is NOT currently declaring the FIFO Limit
Alarm condition.
1 - Indicates that the Jitter Attenuator block (within
Channel_n) is currently declaring the FIFO Limit Alarm
condition.
NOTE: This bit-field is only active if the Jitter Attenuator
(within Channel_n) has been enabled.
2
Receive LOL Condition Declared
R/O
0
Receive LOL (Loss of Lock) Condition Declared:
This READ-ONLY bit-field indicates whether or not the
Receive Section (within Channel_n) is currently declaring
the LOL (Loss of Lock) condition.
The Receive Section (of Channel_n) will declare the LOL
Condition, if any one of the following conditions are met.
• If the frequency of the Recovered Clock signal differs
from that of the signal provided to the E3CLK input (for
E3 applications), the DS3CLK input (for DS3
applications) or the STS-1CLK input (for STS-1
applications) by 0.5% (or 5000ppm) or more.
• If the frequency of the Recovered Clock signal differs
from the line-rate clock signal (for Channel_n) that has
been generated by the SFM Clock Synthesizer PLL (for
SFM Mode Operation) by 0.5% (or 5000ppm) or more.
0 - Indicates that the Receive Section of Channel_n is NOT
currently declaring the LOL Condition.
1 - Indicates that the Receive Section of Channel_n is currently declaring the LOL Condition.
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
1
Receive LOS
Defect Condition
Declared
R/O
0
REV. 1.0.2
DESCRIPTION
Receive LOS (Loss of Signal) Defect Condition
Declared:
This READ-ONLY bit-field indicates whether or not the
Receive Section (within Channel_n) is currently declaring
the LOS defect condition.
The Receive Section (of Channel_n) will declare the LOS
defect condition, if any one of the following conditions is
met.
• If the Digital LOS Detector declares the LOS defect
condition (for DS3 or STS-1 applications)
• If the Analog LOS Detector declares the LOS defect
condition (for DS3 or STS-1 applications)
• If the ITU-T G.775 LOS Detector declares the LOS
defect condition (for E3 applications).
0 - Indicates that the Receive Section of Channel_n is NOT
currently declaring the LOS Defect Condition.
1 - Indicates that the Receive Section of Channel_n is currently declaring the LOS Defect condition.
0
Transmit DMO
Condition Declared
R/O
0
Transmit DMO (Drive Monitor Output) Condition
Declared:
This READ-ONLY bit-field indicates whether or not the
Transmit Section of Channel_n is currently declaring the
DMO Alarm condition.
If configured accordingly, the Transmit Section will either
internally or externally check the Transmit Output DS3/E3/
STS-1 Line signal for bipolar pulses via the TTIP_n and
TRING_n output signals. If the Transmit Section were to
detect no bipolar for 128 consecutive bit-periods, then it
will declare the Transmit DMO Alarm condition. This particular alarm can be used to check for fault conditions on
the Transmit Output Line Signal path.
The Transmit Section will clear the Transmit DMO Alarm
condition the instant that it detects some bipolar activity on
the Transmit Output Line signal.
0 - Indicates that the Transmit Section of Channel_n is
NOT currently declaring the Transmit DMO Alarm condition.
1 - Indicates that the Transmit Section of Channel_n is currently declaring the Transmit DMO Alarm condition.
74
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THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 27: TRANSMIT CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X04
Channel 1 Address Location = 0x0C
Channel 2 Address Location = 0x14
BIT 7
BIT 6
Unused
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Internal
Transmit
Drive Monitor
Insert PRBS
Error
Unused
TAOS
TxCLKINV
TxLEV
R/O
R/O
R/W
R/W
R/O
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-6
Unused
R/O
0
5
Internal Transmit
Drive Monitor
R/W
0
DESCRIPTION
Internal Transmit Drive Monitor Enable - Channel_n:
This READ/WRITE bit-field is used to configure the Transmit Section of Channel_n to either internally or externally
monitor the TTIP_n and TRING_n output pins for bipolar
pulses, in order to determine whether to declare the Transmit DMO Alarm condition.
If the user configures the Transmit Section to externally
monitor the TTIP_n and TRING_n output pins (for bipolar
pulses) then the user must make sure that he/she has connected the MTIP_n and MRING_n input pins to their corresponding TTIP_n and TRING_n output pins (via a 274 ohm
series resistor).
If the user configures the Transmit Section to internally
monitor the TTIP_n and TRING_n output pins (for bipolar
pulses) then the user does NOT need to make sure that
the MTIP_n and MRING_n input pins are connected to the
TTIP_n and TRING_n output pins (via series resistors).
This monitoring will be performed right at the TTIP_n and
TRING_n output pads.
0 - Configures the Transmit Drive Monitor to externally
monitor the TTIP_n and TRING_n output pins for bipolar
pulses.
1 - Configures the Transmit Drive Monitor to internally
monitor the TTIP_n and TRING_n output pins for bipolar
pulses.
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XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
4
Insert PRBS Error
R/W
0
REV. 1.0.2
DESCRIPTION
Insert PRBS Error - Channel_n:
A "0 to 1" transition within this bit-field configures the
PRBS Generator (within the Transmit Section of
Channel_n) to generate a single bit error within the outbound PRBS pattern-stream.
NOTES:
1. This bit-field is only active if the PRBS Generator
and Receiver have been enabled within the
corresponding Channel.
2. After writing the "1" into this register, the user
must execute a write operation to clear this
particular register bit to "0" in order to facilitate the
next "0 to 1" transition in this bit-field.
3
Unused
R/O
0
2
TAOS
R/W
0
Transmit All OneS Pattern - Channel_n:
This READ/WRITE bit-field is used to command the Transmit Section of Channel_n to generate and transmit an
unframed, All Ones pattern via the DS3, E3 or STS-1 line
signal (to the remote terminal equipment).
Whenever the user implements this configuration setting
then the Transmit Section will ignore the data that it is
accepting from the System-side equipment and overwrite
this data with the "All Ones" Pattern.
0 - Configures the Transmit Section to transmit the data
that it accepts from the System-side Interface.
1 - Configures the Transmit Section to generate and transmit the Unframed, All Ones pattern.
76
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REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
1
TxCLKINV
R/W
0
DESCRIPTION
Transmit Clock Invert Select - Channel_n:
This READ/WRITE bit-field is used to select the edge of
the TxCLK_n input that the Transmit Section of Channel_n
will use to sample the TPDATA_n and TNDATA_n input
pins, as described below.
0 - Configures the Transmit Section (within the corresponding channel) to sample the TPDATA_n and TNDATA_n
input pins upon the falling edge of TxCLK_n.
1 - Configures the Transmit Section (within the corresponding channel) to sample the TPDATA_n and TNDATA_n
input pins upon the rising edge of TxCLK_n.
NOTE:
0
TxLEV
R/W
0
Whenever this configuration setting is
accomplished via the Host Mode, it is done on a
per-channel basis.
Transmit Line Build-Out Select - Channel_n:
This READ/WRITE bit-field is used to either enable or disable the Transmit Line Build-Out (e.g., pulse-shaping) circuit within the corresponding channel. The user should set
this bit-field to either "0" or to "1" based upon the following
guidelines.
0 - If the cable length between the Transmit Output (of the
corresponding Channel) and the DSX-3/STSX-1 location is
225 feet or less.
1 - If the cable length between the Transmit Output (of the
corresponding Channel) and the DSX-3/STSX-1 location is
225 feet or more.
The user must follow these guidelines in order to insure
that the Transmit Section (of Channel_n) will always generate a DS3 pulse that complies with the Isolated Pulse Template requirements per Bellcore GR-499-CORE, or an
STS-1 pulse that complies with the Pulse Template
requirements per Telcordia GR-253-CORE.
NOTE: This bit-field is ignored if the channel has been
configured to operate in the E3 Mode.
77
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 28: RECEIVE CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X05
Channel 1 Address Location = 0x0D
Channel 2 Address Location = 0x15
BIT 7
BIT 6
Unused
BIT 5
BIT 4
Disable DLOS Disable ALOS
Detector
Detector
BIT 3
BIT 2
BIT 1
BIT 0
RxCLKINV
LOSMUT
Enable
Receive
Monitor Mode
Enable
Receive
Equalizer
Enable
R/O
R/O
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-6
Unused
R/O
0
5
Disable DLOS
Detector
R/W
0
DESCRIPTION
Disable Digital LOS Detector - Channel_n:
This READ/WRITE bit-field is used to either enable or disable the Digital LOS (Loss of Signal) Detector within
Channel_n, as described below.
0 - Enables the Digital LOS Detector within Channel_n.
NOTE: This is the default condition.
1 - Disables the Digital LOS Detector within Channel_n.
NOTE: This bit-field is only active if Channel_n has been
configured to operate in the DS3 or STS-1 Modes.
4
Disable ALOS
Detector
R/W
0
Disable Analog LOS Detector - Channel_n:
This READ/WRITE bit-field is used to either enable or disable the Analog LOS (Loss of Signal) Detector within
Channel_n, as described below.
0 - Enables the Analog LOS Detector within Channel_n.
NOTE: This is the default condition.
1 - Disables the Analog LOS Detector within Channel_n.
NOTE: This bit-field is only active if Channel_n has been
configured to operate in the DS3 or STS-1 Modes.
3
RxCLKINV
R/W
0
Receive Clock Invert Select - Channel_n:
This READ/WRITE bit-field is used to select the edge of
the RCLK_n output that the Receive Section of Channel_n
will use to output the recovered data via the RPOS_n and
RNEG_n output pins, as described below.
0 - Configures the Receive Section (within the corresponding channel) to output the recovered data via the RPOS_n
and RNEG_n output pins upon the rising edge of RCLK_n.
1 - Configures the Receive Section (within the corresponding channel) to output the recovered data via the RPOS_n
and RNEG_n output pins upon the falling edge of RCLK_n.
78
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REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
2
LOSMUT Enable
R/W
0
Muting upon LOS Enable - Channel_n:
This READ/WRITE bit-field is used to configure the
Receive Section (within Channel_n) to automatically pull
their corresponding Recovered Data Output pins (e.g.,
RPOS_n and RNEG_n) to GND anytime (and for the duration that) the Receive Section declares the LOS defect
condition. In other words, this feature (if enabled) will
cause the Receive Channel to automatically mute the
Recovered data anytime (and for the duration that) the
Receive Section declares the LOS defect condition.
0 - Disables the Muting upon LOS feature. In this setting
the Receive Section will NOT automatically mute the
Recovered Data whenever it is declaring the LOS defect
condition.
1 - Enables the Muting upon LOS feature. In this setting
the Receive Section will automatically mute the Recovered
Data whenever it is declaring the LOS defect condition.
1
Receive Monitor
Mode Enable
R/W
0
Receive Monitor Mode Enable - Channel_n:
This READ/WRITE bit-field is used to configure the
Receive Section of Channel_n to operate in the Receive
Monitor Mode.
If the user configures the Receive Section to operate in the
Receive Monitor Mode, then it will be able to receive a
nominal DSX-3/STSX-1 signal that has been attenuator by
20dB of flat loss along with 6dB of cable loss, in an errorfree manner, and without declaring the LOS defect condition.
0 - Configures the corresponding channel to operate in the
Normal Mode.
1 - Configure the corresponding channel to operate in the
Receive Monitor Mode.
0
Receive Equalizer
Enable
R/W
0
Receive Equalizer Enable - Channel_n:
This READ/WRITE register bit is used to either enable or
disable the Receive Equalizer block within the Receive
Section of Channel_n, as listed below.
0 - Disables the Receive Equalizer within the corresponding channel.
1 - Enables the Receive Equalizer within the corresponding
channel.
DESCRIPTION
NOTE: For virtually all applications, we recommend that
the user set this bit-field to "1" (for all three
channels) and enable the Receive Equalizer.
79
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
TABLE 29: CHANNEL CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X06
Channel 1 Address Location = 0x0E
Channel 2 Address Location = 0x16
BIT 7
BIT 6
Unused
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
PRBS Enable
Ch_n
RLB_n
LLB_n
E3_n
STS-1/DS3_n
SR/DR_n
R/O
R/O
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-6
Unused
R/O
0
5
PRBS Enable
R/W
0
DESCRIPTION
PRBS Generator and Receiver Enable - Channel_n:
This READ/WRITE bit-field is used to either enable or disable the PRBS Generator and Receiver within a given
Channel of the XRT75R03D.
If the user enables the PRBS Generator and Receiver,
then the following will happen.
1. The PRBS Generator (which resides within the
Transmit Section of the Channel) will begin to
generate an unframed, 2^15-1 PRBS Pattern (for
DS3 and STS-1 applications) and an unframed,
2^23-1 PRBS Pattern (for E3 applications).
2. The PRBS Receiver (which resides within the
Receive Section of the Channel) will now be enabled
and will begin to search the incoming data for the
above-mentioned PRBS patterns.
0 - Disables both the PRBS Generator and PRBS Receiver
within the corresponding channel.
1 - Enables both the PRBS Generator and PRBS Receiver
within the corresponding channel.
NOTES:
1. To check and monitor PRBS Bit Errors, Bit 0 (SR/
DR_n) within this register Must be set to "0". This
step will configure the RNEG_n/LCV_n output pin
to function as the PRBS Error Indicator. In this
case, external glue logic will be needed to monitor
and count the number of PRBS Bit Errors that are
detected by the PRBS Receiver.
2. If the user enables the PRBS Generator and
PRBS Receiver, then the Channel will ignore the
data that is being accepted from the System-side
Equipment (via the TPDATA_n and TNDATA_n
input pins) and will overwrite this outbound data
with the PRBS Pattern.
3. Use of the PRBS Generator and Receiver is only
available through the Host Mode.
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BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
4
RLB_n
R/W
0
DESCRIPTION
Loop-Back Select - RLB Bit - Channel_n:
This READ/WRITE bit-field along with the corresponding
LLB_n bit-field is used to configure a given channel (within
the XRT75R03D) into various loop-back modes.
The relationship between the settings for this input pin, the
corresponding LLB_n bit-field and the resulting Loop-back
Mode is presented below.
LLB_n
RLB_n
Loop-back M ode
0
0
Norm al (No Loop-back) Mode
0
1
Rem ote Loop-back Mode
1
0
Analog Local Loop-back Mode
1
1
Digital Local Loop-back Mode
3
LLB_n
R/W
0
Loop-Back Select - LLB Bit-field - Channel_n:
Please see the description (above) for RLB_n.
2
E3_n
R/W
0
E3 Mode Select - Channel_n:
This READ/WRITE bit-field, along with Bit 1 (STS-1/
DS3_n) within this particular register, is used to configure a
given channel (of the XRT75R03D) into either the DS3, E3
or STS-1 Modes, as depicted below.
0 - Configures Channel_n to operate in either the DS3 or
STS-1 Modes, depending upon the state of Bit 1 (STS-1/
DS3_n) within this same register.
1- Configures Channel_n to operate in the E3 Mode.
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BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
1
STS-1/DS3_n
R/W
0
REV. 1.0.2
DESCRIPTION
STS-1/DS3 Mode Select - Channel_n:
This READ/WRITE bit-field, along with Bit 2 (E3_n) is used
to configure a given channel (within the XRT75R03D) into
either the DS3, E3 or STS-1 Modes.
0 - Configures Channel_n to operate in the DS3 Mode
(provided by Bit 2 [E3_n], within this same register) has
been set to "0").
1 - Configures Channel_n to operate in the STS-1 Mode
(provided that Bit 2 [E3_n], within the same register) has
been set to "0".
NOTE: This bit-field is ignored if Bit 2 (E3_n) has been set
to "1". In this case, Channel_n will be configured
to operate in the E3 Mode.
0
SR/DR_n
R/W
0
Single-Rail/Dual-Rail Select - Channel_n:
This READ/WRITE bit-field is used to configure Channel_n
to operate in either the Single-Rail or Dual-Rail Mode.
If the user configures the Channel to operate in the SingleRail Mode, then all of the following will happen.
• The B3ZS/HDB3 Encoder and Decoder blocks (within
Channel_n) will be enabled.
• The Transmit Section of Channel_n will accept all of the
outbound data (from the System-side Equipment) via the
TPDATA_n (or TxDATA_n) input pin.
• The Receive Section of each channel will output all of
the recovered data (to the System-side Equipment) via
the RPOS_n output pin.
• The corresponding RNEG_n/LCV_n output pin will now
function as the LCV (Line Code Violation or Excessive
Zero Event) indicator output pin for Channel_n.
If the user configures Channel_n to operate in the DualRail Mode, then all of the following will happen.
• The B3ZS/HDB3 Encoder and Decoder blocks of
Channel_n will be disabled.
• The Transmit Section of Channel_n will be configured to
accept positive-polarity data via the TPDATA_n input pin
and negative-polarity data via the TNDATA_n input pin.
• The Receive Section of Channel_n will pulse the
RPOS_n output pin "High" (for one period of RCLK_n)
for each time a positive-polarity pulse is received via the
RTIP_n/RRING_n input pins. Likewise, the Receive
Section of each channel will also pulse the RNEG_n
output pin "High" (for one period of RCLK_n) for each
time a negative-polarity pulse is received via the
RTIP_n/RRING_n input pins.
0 - Configures Channel_n to operate in the Dual-Rail
Mode.
1 - Configures Channel_n to operate in the Single-Rail
Mode.
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TABLE 30: JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07
Channel 1 Address Location = 0x0F
Channel 2 Address Location = 0x17
BIT 7
BIT 6
BIT 5
Unused
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SONET APS
Recovery
Time Disable
Ch_n
JA RESET
Ch_n
JA1 Ch_n
JA in Tx Path
Ch_n
JA0 Ch_n
R/O
R/O
R/O
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
7-3
Unused
R/O
0
4
SONET APS
Recovery Time
Mode Disable Ch_n
R/W
O
DESCRIPTION
SONET APS Recovery Time Mode Disable - Channel n:
This READ/WRITE bit-field is used to either enable or disable the "SONET APS Recovery Time" Mode within the Jitter Attenuator, associated with Channel n.
If this feature is enabled the Jitter Attenuator (associated
with Channel n) will be configured such that the user’s system will be able to comply with the APS Recovery Time
requirements of 50ms (per Telcordia GR-253-CORE).
If this feature is disabled the System using the
XRT75R03D will NOT comply with the APS Recovery Time
requirements of 50ms.
NOTE: In this case, "APS Recovery Time" is defined as the
amount of time that will elapse between (a) the
instant that Automatic Protection Switching (APS)
is employed (either "automatically" or upon
Software Command), and (b) the instant that an
entity (which is responsible for acquiring and
maintaining DS3/E3 frame synchronization with
the DS3/E3 data-stream that has been de-mapped
from SONET by the Mapper device) has reacquired DS3/E3 frame synchronization, after the
APS event.
0 - Enables the "SONET APS Recovery Time" Mode.
1 - Disables the "SONET APS Recovery Time" Mode.
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BIT NUMBER
NAME
TYPE
DEFAULT
VALUE
3
JA RESET Ch_n
R/W
0
REV. 1.0.2
DESCRIPTION
Jitter Attenuator RESET - Channel_n:
Writing a "0 to 1" transition within this bit-field will configure
the Jitter Attenuator (within Channel_n) to execute a
RESET operation.
Whenever the user executes a RESET operation, then all
of the following will occur.
• The READ and WRITE pointers (within the Jitter
Attenuator FIFO) will be reset to their default values.
• The contents of the Jitter Attenuator FIFO will be
flushed.
NOTE: The user must follow up any "0 to 1" transition with
the appropriate write operate to set this bit-field
back to "0", in order to resume normal operation
with the Jitter Attenuator.
2
JA1 Ch_n
R/W
0
Jitter Attenuator Configuration Select Input - Bit 1:
This READ/WRITE bit-field, along with Bit 0 (JA0 Ch_n) is
used to do any of the following.
• To enable or disable the Jitter Attenuator corresponding
to Channel_n.
• To select the FIFO Depth for the Jitter Attenuator within
Channel_n.
The relationship between the settings of these two bitfields and the Enable/Disable States, and FIFO Depths is
presented below.
JA0
JA1
Jitter Attenuator Mode
0
0
FIFO Depth = 16 bits
0
1
FIFO Depth = 32 bits
1
0
SONET/SDH De-Sync Mode
1
1
Jitter Attenuator Disabled
1
JA in Tx Path Ch_n
R/W
0
Jitter Attenuator in Transmit/Receive Path Select Bit:
This input pin is used to configure the Jitter Attenuator
(within Channel_n) to operate in either the Transmit or
Receive path, as described below.
0 - Configures the Jitter Attenuator (within Channel_n) to
operate in the Receive Path.
1 - Configures the Jitter Attenuator (within Channel_n) to
operate in the Transmit Path.
0
JA0 Ch_n
R/W
0
Jitter Attenuator Configuration Select Input - Bit 0:
Please see the description for Bit 2 (JA1 Ch_n).
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9.0 DIAGNOSTIC FEATURES:
PRBS Generator and Detector:
9.1
The XRT75R03D contains an on-chip Pseudo Random Binary Sequence (PRBS) generator and detector for
diagnostic purpose. This feature is only available in Host mode. With the PRBSEN_n bit = “1”, the transmitter
will send out PRBS of 223-1 in E3 rate or 215-1 in STS-1/DS3 rate. At the same time, the receiver PRBS
detector is also enabled. When the correct PRBS pattern is detected by the receiver, the RNEG/LCV pin will go
“Low” to indicate PRBS synchronization has been achieved. When the PRBS detector is not in sync the
PRBSLS bit will be set to “1” and RNEG/LCV pin will go “High”.
With the PRBS mode enabled, the user can also insert a single bit error by toggling “INSPRBS” bit. This is
done by writing a “1” to INSPRBS bit. The receiver at RNEG/LCV pin will pulse “High” for one RxClk cycle for
every bit error detected. Any subsequent single bit error insertion must be done by first writing a “0” to
INSPRBS bit and followed by a “1”.
Figure 25 shows the status of RNEG/LCV pin when the XRT75R03D is configured in PRBS mode.
NOTE: In PRBS mode, the device is forced to operate in Single-Rail Mode.
FIGURE 26. PRBS MODE
RClk
SYNC LOSS
RNEG/LCV
PRBS SYNC
Single Bit Error
LOOPBACKS:
9.2
The XRT75R03D offers three loopback modes for diagnostic purposes. In Hardware mode, the loopback
modes are selected via the RLB_n and LLB_n pins. In Host mode, the RLB_n and LLB_n bits n the Channel
control registers select the loopback modes.
9.2.1
ANALOG LOOPBACK:
In this mode, the transmitter outputs (TTIP_n and TRING_n) are connected internally to the receiver inputs
(RTIP_n and RRING_n) as shown in Figure 26. Data and clock are output at RCLK_n, RPOS_n and RNEG_n
pins for the corresponding transceiver. Analog loopback exercises most of the functional blocks of the device
including the jitter attenuator which can be selected in either the transmit or receive path.
XRT75R03D can be configured in Analog Loopback either in Hardware mode via the LLB_n and RLB_n pins
or in Host mode via LLB_n and RLB_n bits in the channel control registers.
NOTES:
1. In the Analog loopback mode, data is also output via TTIP_n and TRING_n pins.
2. Signals on the RTIP_n and RRING_n pins are ignored during analog loopback.
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REV. 1.0.2
TNDATA
RCLK
1
HDB3/B3ZS
DECODER
RPOS
RNEG
JITTER 2
ATTENUATOR
1
HDB3/B3ZS
ENCODER
TCLK
TPDATA
TIMING
CONTROL
JITTER 2
ATTENUATOR
FIGURE 27. ANALOG LOOPBACK
DATA &
CLOCK
RECOVERY
TTIP
Tx
TRING
1
if enabled
2 if enabled and selected in either Receive or
Transmit path
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Rx
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REV. 1.0.2
9.2.2
DIGITAL LOOPBACK:
The Digital Loopback function is available either in Hardware mode or Host mode. When the Digital Loopback
is selected, the transmit clock (TxClk_n) and transmit data inputs (TPDATA_n & TNDATA_n) are looped back
and output onto the RxClk_n, RPOS_n and RNEG_n pins as shown in Figure 27.
TPDATA
TNDATA
RCLK
1
HDB3/B3ZS
DECODER
RPOS
RNEG
JITTER 2
ATTENUATOR
1
HDB3/B3ZS
ENCODER
TCLK
TIMING
CONTROL
JITTER 2
ATTENUATOR
FIGURE 28. DIGITAL LOOPBACK
DATA &
CLOCK
RECOVERY
TTIP
Tx
TRING
RTIP
Rx
RRING
1
if enabled
if enabled and selected in either Receive or
Transmit path
2
9.2.3
REMOTE LOOPBACK:
With Remote loopback activated as shown in Figure 28, the receive data on RTIP and RRING is looped back
after the jitter attenuator (if selected in receive or transmit path) to the transmit path using RxClk as transmit
timing. The receive data is also output via the RPOS and RNEG pins.
During the remote loopback mode, if the jitter attenuator is selected in the transmit path, the receive data after
the Clock and Data Recovery Block is looped back to the transmit path and passed through the jitter attenuator
using RxClk as the transmit timing.
NOTE: Input signals on TxClk, TPDATA and TNDATA are ignored during Remote loopback.
TNDATA
RCLK
HDB3/B3ZS
DECODER
RPOS
1
RNEG
JITTER 2
ATTENUATOR
1
HDB3/B3ZS
ENCODER
TCLK
TPDATA
TIMING
CONTROL
JITTER 2
ATTENUATOR
FIGURE 29. REMOTE LOOPBACK
DATA &
CLOCK
RECOVERY
TTIP
Tx
TRING
1
if enabled
if enabled and selected in either Receive or
Transmit path
2
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REV. 1.0.2
TRANSMIT ALL ONES (TAOS):
9.3
Transmit All Ones (TAOS) can be set either in Hardware mode by pulling the TAOS_n pins “High” or in Host
mode by setting the TAOS_n control bits to “1” in the Channel control registers. When the TAOS is set, the
Transmit Section generates and transmits a continuous AMI all “1’s” pattern on TTIP_n and TRING_n pins. The
frequency of this “1’s” pattern is determined by TClk_n.TAOS data path is shown in Figure 29. TAOS does not
operate in Analog loopback or Remote Digital loopback mode. It will function in Digital loopback mode.
TCLK
1
HDB3/B3ZS
ENCODER
TPDATA
TNDATA
JITTER 2
ATTENUATOR
FIGURE 30. TRANSMIT ALL ONES (TAOS)
TIMING
CONTROL
Tx
TTIP
Transmit All 1
TRING
1
HDB3/B3ZS
DECODER
RCLK
RPOS
RNEG
JITTER 2
ATTENUATOR
TAOS
DATA &
CLOCK
RECOVERY
RTIP
Rx
RRING
1
if enabled
if enabled and selected in either Receive or
Transmit path
2
10.0 THE SONET/SDH DE-SYNC FUNCTION WITHIN THE XRT75R03D
The XRT75R03D LIU IC is very similar to the XRT75R03 in that they are both 3-Channel DS3/E3/STS-1 LIU
devices that also contain Jitter Attenuator blocks within each of the three channels. They are also pin to pin
compatible with each other. However, the Jitter Attenuators within the XRT75R03D has some enhancements
over and above those within the XRT75R03 (non-D) device. The Jitter Attenuator blocks within the
XRT75R03D will support all of the modes and features that exist in the XRT75R03 (non-D) device and in
addition they also support a SONET/SDH De-Sync Mode not available within the XRT75R03.
NOTE: The "D" suffix within the part number, XRT75R03D stands for "De-Sync".
The SONET/SDH De-Sync feature of the Jitter Attenuator blocks in the XRT75R03D permits the user to design
a SONET/SDH PTE (Path Terminating Equipment) that will comply with all of the following Intrinsic Jitter and
Wander requirements.
• For SONET Applications
■
Category I Intrinsic Jitter Requirements per Telcordia GR-253-CORE (for DS3 Applications)
■
ANSI T1.105.03b-1997 - SONET Jitter at Network Interfaces - DS3 Wander Supplement
• For SDH Applications
■
Jitter and Wander Generation Requirements per ITU-T G.783 (for DS3 and E3 Applications)
Specifically, if the user designs in the XRT75R03D along with a SONET/SDH Mapper IC (which can be
realized as either a standard product or as a custom logic solution, in an ASIC or FPGA), then the followind can
be accomplished;
• The Mapper can receive an STS-N or an STM-M signal (which is carrying asynchronously-mapped DS3 and/
or E3 signals) and byte de-interleave this data into N STS-1 or 3*M VC-3 signals
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• The Mapper will then terminate these STS-1 or VC-3 signals and will de-map out this DS3 or E3 data from
the incoming STS-1 SPEs or VC-3s, and output this DS3 or E3 to the DS3/E3 Facility-side towards the
XRT75R03D
• This DS3 or E3 signal (as it is output from these Mapper devices) will contain a large amount intrinsic jitter
and wander due to (1) the process of asynchronously mapping a DS3 or E3 signal into a SONET or SDH
signal, (2) the occurrence of Pointer Adjustments within the SONET or SDH signal (transporting these DS3
or E3 signals) as it traverses the SONET/SDH network, and (3) clock gapping.
• When the XRT75R03D has been configured to operate in the "SONET/SDH De-Sync" Mode, then it will (1)
accept this jittery DS3 or E3 clock and data signal from the Mapper device (via the Transmit System-side
interface) and (2) through the Jitter Attenuator, the XRT75R03D will reduce the Jitter and Wander amplitude
within these DS3 or E3 signals such that they (when output onto the line) will comply with the abovementioned intrinsic jitter and wander specifications.
10.1
BACKGROUND AND DETAILED INFORMATION - SONET DE-SYNC APPLICATIONS
This section provides an in-depth discussion on the mechanisms that will cause Jitter and Wander within a
DS3 or E3 signal that is being transported across a SONET or SDH Network. A lot of this material is
introductory, and can be skipped by the engineer that is already experienced in SONET/SDH designs. In this
case, the user should proceed directly to “Section 10.8, Designing with the XRT75R03D” on page 118, which
describes how to configure the XRT75R03D in the appropriate set of modes in order to support this
application.
In the wide-area network (WAN) in North America it is often necessary to transport a DS3 signal over a long
distance (perhaps over a thousand miles) in order to support a particular service. Now rather than realizing
this transport of DS3 data, by using over a thousand miles of coaxial cable (interspaced by a large number of
DS3 repeaters) a common thing to do is to route this DS3 signal to a piece of equipment (such as a Terminal
MUX, which in the "SONET Community" is known as a PTE or Path Terminating Equipment). This Terminal
MUX will asynchronously map the DS3 signal into a SONET signal. At this point, the SONET network will now
transport this asynchronously mapped DS3 signal from one PTE to another PTE (which is located at the other
end of the SONET network). Once this SONET signal arrives at the remote PTE, this DS3 signal will then be
extracted from the SONET signal, and will be output to some other DS3 Terminal Equipment for further
processing.
Similar things are done outside of North America. In this case, this DS3 or E3 signal is routed to a PTE, where
it is asynchronously mapped into an SDH signal. This asynchronously mapped DS3 or E3 signal is then
transported across the SDH network (from one PTE to the PTE at the other end of the SDH network). Once
this SDH signal arrives at the remote PTE, this DS3 or E3 signal will then be extracted from the SDH signal,
and will be output to some other DS3/E3 Terminal Equipment for further processing.
Figure 31 presents an illustration of this approach to transporting DS3 data over a SONET Network
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REV. 1.0.2
FIGURE 31. A SIMPLE ILLUSTRATION OF A DS3 SIGNAL BEING MAPPED INTO AND TRANSPORTED OVER THE SONET
NETWORK
SONET
Network
DS3 Data
PTE
PTE
PTE
PTE
DS3 Data
As mentioned above a DS3 or E3 signal will be asynchronously mapped into a SONET or SDH signal and then
transported over the SONET or SDH network. At the remote PTE this DS3 or E3 signal will be extracted (or
de-mapped) from this SONET or SDH signal, where it will then be routed to DS3 or E3 terminal equipment for
further processing.
In order to insure that this "de-mapped" DS3 or E3 signal can be routed to any industry-standard DS3 or E3
terminal equipment, without any complications or adverse effect on the network, the Telcordia and ITU-T
standard committees have specified some limits on both the Intrinsic Jitter and Wander that may exist within
these DS3 or E3 signals as they are de-mapped from SONET/SDH. As a consequence, all PTEs that maps
and de-mapped DS3/E3 signals into/from SONET/SDH must be designed such that the DS3 or E3 data that is
de-mapped from SONET/SDH by these PTEs must meet these Intrinsic Jitter and Wander requirements.
As mentioned above, the XRT75R03D can assist the System Designer (of SONET/SDH PTE) by insuring that
their design will meet these Intrinsic Jitter and Wander requirements.
This section of the data sheet will present the following information to the user.
• Some background information on Mapping DS3/E3 signals into SONET/SDH and de-mapping DS3/E3
signals from SONET/SDH.
• A brief discussion on the causes of jitter and wander within a DS3 or E3 signal that mapped into a SONET/
SDH signal, and is transported across the SONET/SDH Network.
• A brief review of these Intrinsic Jitter and Wander requirements in both SONET and SDH applications.
• A brief review on the Intrinsic Jitter and Wander measurement results (of a de-mapped DS3 or E3 signal)
whenever the XRT75R03D device is used in a system design.
• A detailed discussion on how to design with and configure the XRT75R03D device such that the end-system
will meet these Intrinsic Jitter and Wander requirements.
In a SONET system, the relevant specification requirements for Intrinsic Jitter and Wander (within a DS3 signal
that is mapped into and then de-mapped from SONET) are listed below.
• Telcordia GR-253-CORE Category I Intrinsic Jitter Requirements for DS3 Applications (Section 5.6), and
• ANSI T1.105.03b-1997 - SONET Jitter at Network Interfaces - DS3 Wander Supplement
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In general, there are three (3) sources of Jitter and Wander within an asynchronously-mapped DS3 signal that
the system designer must be aware of. These sources are listed below.
• Mapping/De-Mapping Jitter
• Pointer Adjustments
• Clock Gapping
Each of these sources of jitter/wander will be defined and discussed in considerable detail within this Section.
In order to accomplish all of this, this particular section will discuss all of the following topics in details.
• How DS3 data is mapped into SONET, and how this mapping operation contributes to Jitter and Wander
within this "eventually de-mapped" DS3 signal.
• How this asynchronously-mapped DS3 data is transported throughout the SONET Network, and how
occurrences on the SONET network (such as pointer adjustments) will further contributes to Jitter and
Wander within the "eventually de-mapped" DS3 signal.
• A review of the Category I Intrinsic Jitter Requirements (per Telcordia GR-253-CORE) for DS3 applications
• A review of the DS3 Wander requirements per ANSI T1.105.03b-1997
• A review of the Intrinsic Jitter and Wander Capabilities of the XRT75R03D in a typical system application
• An in-depth discussion on how to design with and configure the XRT75R03D to permit the system to the
meet the above-mentioned Intrinsic Jitter and Wander requirements
NOTE: An in-depth discussion on SDH De-Sync Applications will be presented in the next revision of this data sheet.
10.2
MAPPING/DE-MAPPING JITTER/WANDER
Mapping/De-Mapping Jitter (or Wander) is defined as that intrinsic jitter (or wander) that is induced into a DS3
signal by the "Asynchronous Mapping" process. This section will discuss all of the following aspects of
Mapping/De-Mapping Jitter.
• How DS3 data is mapped into an STS-1 SPE
• How frequency offsets within either the DS3 signal (being mapped into SONET) or within the STS-1 signal
itself contributes to intrinsic jitter/wander within the DS3 signal (being transported via the SONET network).
10.2.1
HOW DS3 DATA IS MAPPED INTO SONET
Whenever a DS3 signal is asynchronously mapped into SONET, this mapping is typically accomplished by a
PTE accepting DS3 data (from some remote terminal) and then loading this data into certain bit-fields within a
given STS-1 SPE (or Synchronous Payload Envelope). At this point, this DS3 signal has now been
asynchronously mapped into an STS-1 signal. In most applications, the SONET Network will then take this
particular STS-1 signal and will map it into "higher-speed" SONET signals (e.g., STS-3, STS-12, STS-48, etc.)
and will then transport this asynchronously mapped DS3 signal across the SONET network, in this manner. As
this "asynchronously-mapped" DS3 signal approaches its "destination" PTE, this STS-1 signal will eventually
be de-mapped from this STS-N signal. Finally, once this STS-1 signal reaches the "destination" PTE, then this
asynchronously-mapped DS3 signal will be extracted from this STS-1 signal.
10.2.1.1
A Brief Description of an STS-1 Frame
In order to be able to describe how a DS3 signal is asynchronously mapped into an STS-1 SPE, it is important
to define and understand all of the following.
• The STS-1 frame structure
• The STS-1 SPE (Synchronous Payload Envelope)
• Telcordia GR-253-CORE’s recommendation on mapping DS3 data into an STS-1 SPE
An STS-1 frame is a data-structure that consists of 810 bytes (or 6480 bits). A given STS-1 frame can be
viewed as being a 9 row by 90 byte column array (making up the 810 bytes). The frame-repetition rate (for an
STS-1 frame) is 8000 frames/second. Therefore, the bit-rate for an STS-1 signal is (6480 bits/frame * 8000
frames/sec =) 51.84Mbps.
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A simple illustration of this SONET STS-1 frame is presented below in Figure 32.
FIGURE 32. A SIMPLE ILLUSTRATION OF THE SONET STS-1 FRAME
90 Bytes
9 Rows
STS-1 Frame (810 Bytes)
Last Byte of the STS-1 Frame
First Byte of the STS-1 Frame
Figure 32 indicates that the very first byte of a given STS-1 frame (to be transmitted or received) is located in
the extreme upper left hand corner of the 90 column by 9 row array, and that the very last byte of a given STS1 frame is located in the extreme lower right-hand corner of the frame structure. Whenever a Network Element
transmits a SONET STS-1 frame, it starts by transmitting all of the data, residing within the top row of the STS1 frame structure (beginning with the left-most byte, and then transmitting the very next byte, to the right). After
the Network Equipment has completed its transmission of the top or first row, it will then proceed to transmit the
second row of data (again starting with the left-most byte, first). Once the Network Equipment has transmitted
the last byte of a given STS-1 frame, it will proceed to start transmitting the very next STS-1 frame.
The illustration of the STS-1 frame (in Figure 32) is very simplistic, for multiple reasons. One major reason is
that the STS-1 frame consists of numerous types of bytes. For the sake of discussion within this data sheet,
the STS-1 frame will be described as consisting of the following types (or groups) of bytes.
• The Transport Overheads (or TOH) Bytes
• The Envelope Capacity Bytes
10.2.1.1.1
The Transport Overhead (TOH) Bytes
The Transport Overhead or TOH bytes occupy the very first three (3) byte columns within each STS-1 frame.
Figure 33 presents another simple illustration of an STS-1 frame structure. However, in this case, both the
TOH and the Envelope Capacity bytes are designated in this Figure.
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FIGURE 33. A SIMPLE ILLUSTRATION OF THE STS-1 FRAME STRUCTURE WITH THE TOH AND THE ENVELOPE
CAPACITY BYTES DESIGNATED
90 Bytes
3 Bytes
TOH
87 Bytes
Envelope Capacity
9 Row
Since the TOH bytes occupy the first three byte columns of each STS-1 frame, and since each STS-1 frame
consists of nine (9) rows, then we can state that the TOH (within each STS-1 frame) consists of 3 byte columns
x 9 rows = 27 bytes. The byte format of the TOH is presented below in Figure 34.
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FIGURE 34. THE BYTE-FORMAT OF THE TOH WITHIN AN STS-1 FRAME
3 Byte Columns
A1
A1
B1
B1
D1
D1
H1
H1
9 Rows
B2
B2
D4
D4
D7
D7
D10
D10
S1
S1
87 Byte Columns
A2
A2
C1
C1
E1
E1
D2
D2
F1
F1
D3
D3
H2
H2
K1
K1
H3
H3
K2
K2
D5
D5
D8
D8
D6
D6
D9
D9
D11
D11
M0
M0
D12
D12
E2
E2
Envelope
EnvelopeCapacity
Capacity
Bytes
Bytes
The TOH Bytes
In general, the role/purpose of the TOH bytes is to fulfill the following functions.
• To support STS-1 Frame Synchronization
• To support Error Detection within the STS-1 frame
• To support the transmission of various alarm conditions such as RDI-L (Line - Remote Defect Indicator) and
REI-L (Line - Remote Error Indicator)
• To support the Transmission and Reception of "Section Trace" Messages
• To support the Transmission and Reception of OAM&P Messages via the DCC Bytes (Data Communication
Channel bytes - D1 through D12 byte)
The roles of most of the TOH bytes is beyond the scope of this Data Sheet and will not be discussed any
further. However, there are a three TOH bytes that are important from the stand-point of this data sheet, and
will discussed in considerable detail throughout this document. These are the H1 and H2 (e.g., the SPE
Pointer) bytes and the H3 (e.g., the Pointer Action) byte.
Figure 35 presents an illustration of the Byte-Format of the TOH within an STS-1 Frame, with the H1, H2 and
H3 bytes highlighted.
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FIGURE 35. THE BYTE-FORMAT OF THE TOH WITHIN AN STS-1 FRAME
3 Byte Columns
9 Rows
87 Byte Columns
A1
A1
B1
B1
A2
A2
E1
E1
C1
C1
F1
F1
D1
D1
H1
H1
D2
D2
H2
H2
D3
D3
H3
H3
B2
B2
D4
D4
K1
K1
D5
D5
K2
K2
D6
D6
D7
D7
D10
D10
D8
D8
D11
D11
D9
D9
D12
D12
S1
S1
M0
M0
E2
E2
Envelope
EnvelopeCapacity
Capacity
Bytes
Bytes
The TOH Bytes
Although the role of the H1, H2 and H3 bytes will be discussed in much greater detail in “Section 10.3, Jitter/
Wander due to Pointer Adjustments” on page 102. For now, we will simply state that the role of these bytes is
two-fold.
• To permit a given PTE (Path Terminating Equipment) that is receiving an STS-1 data to be able to locate the
STS-1 SPE (Synchronous Payload Envelope) within the Envelope Capacity of this incoming STS-1 data
stream and,
• To inform a given PTE whenever Pointer Adjustment and NDF (New Data Flag) events occur within the
incoming STS-1 data-stream.
10.2.1.1.2
The Envelope Capacity Bytes within an STS-1 Frame
In general, the Envelope Capacity Bytes are any bytes (within an STS-1 frame) that exist outside of the TOH
bytes. In short, the Envelope Capacity contains the STS-1 SPE (Synchronous Payload Envelope). In fact,
every single byte that exists within the Envelope Capacity also exists within the STS-1 SPE. The only
difference that exists between the "Envelope Capacity" as defined in Figure 34 and Figure 35 above and the
STS-1 SPE is that the Envelope Capacity is aligned with the STS-1 framing boundaries and the TOH bytes;
whereas the STS-1 SPE is NOT aligned with the STS-1 framing boundaries, nor the TOH bytes.
The STS-1 SPE is an "87 byte column x 9 row" data-structure (which is the exact same size as is the Envelope
Capacity) that is permitted to "float" within the "Envelope Capacity". As a consequence, the STS-1 SPE (within
an STS-1 data-stream) will typically straddle across an STS-1 frame boundary.
10.2.1.1.3
The Byte Structure of the STS-1 SPE
As mentioned above, the STS-1 SPE is an 87 byte column x 9 row structure. The very first column within the
STS-1 SPE consists of some overhead bytes which are known as the "Path Overhead" (or POH) bytes. The
remaining portions of the STS-1 SPE is available for "user" data. The Byte Structure of the STS-1 SPE is
presented below in Figure 36.
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FIGURE 36. ILLUSTRATION OF THE BYTE STRUCTURE OF THE STS-1 SPE
87 Bytes
1 Byte
9 Rows
J1
B3
C2
G1
F2
H4
Z3
Z4
Z5
86 Bytes
Payload (or User) Data
In general, the role/purpose of the POH bytes is to fulfill the following functions.
• To support error detection within the STS-1 SPE
• To support the transmission of various alarm conditions such as RDI-P (Path - Remote Defect Indicator) and
REI-P (Path - Remote Error Indicator)
• To support the transmission and reception of "Path Trace" Messages
The role of the POH bytes is beyond the scope of this data sheet and will not be discussed any further.
10.2.1.2
Mapping DS3 data into an STS-1 SPE
Now that we have defined the STS-1 SPE, we can now describe how a DS3 signal is mapped into an STS-1
SPE. As mentioned above, the STS-1 SPE is basically an 87 byte column x 9 row structure of data. The very
first byte column (e.g., in all 9 bytes) consists of the POH (Path Overhead) bytes. All of the remaining bytes
within the STS-1 SPE is simply referred to as "user" or "payload" data because this is the portion of the STS-1
signal that is used to transport "user data" from one end of the SONET network to the other. Telcordia GR253-CORE specifies the approach that one must use to asynchronously map DS3 data into an STS-1 SPE. In
short, this approach is presented below in Figure 37.
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FIGURE 37. AN ILLUSTRATION OF TELCORDIA GR-253-CORE’S RECOMMENDATION ON HOW MAP DS3 DATA INTO
AN STS-1 SPE
•
For DS3 Mapping, the STS-1 SPE has the following structure.
87 bytes
POH
R
R
C1
25I
R
C2
I
25I
R
C3
I
25I
R
R
R
R
C1
C1
25I
25I
R
R
C2
C2
I
I
25I
25I
R
R
C3
C3
I
I
25I
25I
R
R
R
R
C1
C1
25I
25I
R
R
C2
C2
I
I
25I
25I
R
R
C3
C3
I
I
25I
25I
R
R
R
R
C1
C1
25I
25I
R
R
C2
C2
I
I
25I
25I
R
R
C3
C3
I
I
25I
25I
R
R
R
R
C1
C1
25I
25I
R
R
C2
C2
I
I
25I
25I
R
R
C3
C3
I
I
25I
25I
i = DS3 data
I = [i, i, i, i, i, i, i, i]
R = [r, r, r, r, r, r, r, r]
r = fixed stuff bit
Fixed
Stuff
C1 = [r, r, c, i, i, i, i, i]
c = stuff control bit
C2 = [c, c, r, r, r, r, r, r]
s = stuff opportunity bit
C3 = [c, c, r, r, o, o, r, s]
o = overhead communications channel bit
Figure 37 was copied directly out of Telcordia GR-253-CORE. However, this figure can be simplified and
redrawn as depicted below in Figure 38.
FIGURE 38. A SIMPLIFIED "BIT-ORIENTED" VERSION OF TELCORDIA GR-253-CORE’S RECOMMENDATION ON HOW
TO MAP DS3 DATA INTO AN STS-1 SPE
POH
18r
c
205i
16r
2c
6r
208i
16r
2c
2r
2o
1r
s
208i
18r
18r
c
c
205i
205i
16r
16r
2c
2c
6r
6r
208i
208i
16r
16r
2c
2c
2r
2r
2o
2o
1r
1r
s
s
208i
208i
18r
18r
18r
c
c
c
205i
205i
205i
16r
16r
16r
2c
2c
2c
6r
6r
6r
208i
208i
208i
16r
16r
16r
2c
2c
2c
2r
2r
2r
2o
2o
2o
1r
1r
1r
s
s
s
208i
208i
208i
18r
18r
18r
c
c
c
205i
205i
205i
16r
16r
16r
2c
2c
2c
6r
6r
6r
208i
208i
208i
16r
16r
16r
2c
2c
2c
2r
2r
2r
2o
2o
2o
1r
1r
1r
s
s
s
208i
208i
208i
r
- Fixed Stuff Bits
c
- Stuff Control/Indicator Bits
i
- DS3 Data Bits
s
- Stuff Opportunity Bits
o
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Figure 38 presents an alternative illustration of Telcordia GR-253-CORE’s recommendation on how to
asynchronously map DS3 data into an STS-1 SPE. In this case, the STS-1 SPE bit-format is expressed purely
in the form of "bit-types" and "numbers of bits within each of these types of bits". If one studies this figure
closely he/she will notice that this is the same "87 byte column x 9 row" structure that we have been talking
about when defining the STS-1 SPE. However, in this figure, the "user-data" field is now defined and is said to
consist of five (5) different types of bits. Each of these bit-types play a role when asynchronously mapping a
DS3 signal into an STS-1 SPE. Each of these types of bits are listed and described below.
Fixed Stuff Bits
Fixed Stuff bits are simply "space-filler" bits that simply occupy space within the STS-1 SPE. These bit-fields
have no functional role other than "space occupation". Telcordia GR-253-CORE does not define any particular
value that these bits should be set to. Each of the 9 rows, within the STS-1 SPE will contain 59 of these "fixed
stuff" bits.
DS3 Data Bits
The DS3 Data-Bits are (as its name implies) used to transport the DS3 data-bits within the STS-1 SPE. If the
STS-1 SPE is transporting a framed DS3 data-stream, then these DS3 Data bits will carry both the "DS3
payload data" and the "DS3 overhead bits". Each of the 9 rows, within the STS-1 SPE will contain 621 of these
"DS3 Data bits". This means that each STS-1 SPE contains 5,589 of these DS3 Data bit-fields.
Stuff Opportunity Bits
The "Stuff" Opportunity bits will function as either a "stuff" (or junk) bit, or it will carry a DS3 data-bit. The
decision as to whether to have a "Stuff Opportunity" bit transport a "DS3 data-bit" or a "stuff" bit depends upon
the "timing differences" between the DS3 data that is being mapped into the STS-1 SPE and the timing source
that is driving the STS-1 circuitry within the PTE.
As will be described later on, these "Stuff Opportunity" Bits play a very important role in "frequency-justifying"
the DS3 data that is being mapped into the STS-1 SPE. These "Stuff Opportunity" bits also play a critical role
in inducing Intrinsic Jitter and Wander within the DS3 signal (as it is de-mapped by the remote PTE).
Each of the 9 rows, within the STS-1 SPE consists of one (1) Stuff Opportunity bit. Hence, there are a total of
nine Stuff Opportunity" bits within each STS-1 SPE.
Stuff Control/Indicator Bits
Each of the nine (9) rows within the STS-1 SPE contains five (5) Stuff Control/Indicator bits. The purpose of
these "Stuff Control/Indicator" bits is to indicate (to the de-mapping PTE) whether the "Stuff Opportunity" bits
(that resides in the same row) is a "Stuff" bit or is carrying a DS3 data bit.
If all five of these "Stuff Control/Indicator" bits, within a given row are set to "0", then this means that the
corresponding "Stuff Opportunity" bit (e.g., the "Stuff Opportunity" bit within the same row) is carrying a DS3
data bit.
Conversely, if all five of these "Stuff Control/Indicator" bits, within a given row are set to "1" then this means that
the corresponding "Stuff Opportunity" bit is carrying a "stuff" bit.
Overhead Communication Bits
Telcordia GR-253-CORE permits the user to use these two bits (for each row) as some sort of
"Communications" bit. Some Mapper devices, such as the XRT94L43 12-Channel DS3/E3/STS-1 to STS-12/
STM-1 Mapper and the XRT94L33 3-Channel DS3/E3/STS-1 to STS-3/STM-1 Mapper IC (both from Exar
Corporation) do permit the user to have access to these bit-fields.
However, in general, these particular bits can also be thought of as "Fixed Stuff" bits, that mostly have a "space
occupation" function.
10.2.2
DS3 Frequency Offsets and the Use of the "Stuff Opportunity" Bits
In order to fully convey the role that the "stuff-opportunity" bits play, when mapping DS3 data into SONET, we
will present a detailed discussion of each of the following "Mapping DS3 into STS-1" scenarios.
• The Ideal Case (e.g., with no frequency offsets)
• The 44.736Mbps + 1 ppm Case
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• The 44.736MHz - 1ppm Case
Throughout each of these cases, we will discuss how the resulting "bit-stuffing" (that was done when mapping
the DS3 signal into SONET) affects the amount of intrinsic jitter and wander that will be present in the DS3
signal, once it is ultimately de-mapped from SONET.
10.2.2.1
The Ideal Case for Mapping DS3 data into an STS-1 Signal (e.g., with no Frequency
Offsets)
Let us assume that we are mapping a DS3 signal, which has a bit rate of exactly 44.736Mbps (with no
frequency offset) into SONET. Further, let us assume that the SONET circuitry within the PTE is clocked at
exactly 51.84MHz (also with no frequency offset), as depicted below.
FIGURE 39. A SIMPLE ILLUSTRATION OF A DS3 DATA-STREAM BEING MAPPED INTO AN STS-1 SPE, VIA A PTE
DS3_Data_In
STS-1_Data_Out
PTE
PTE
51.84MHz + 0ppm
44.736MHz + 0ppm
Given the above-mentioned assumptions, we can state the following.
• The DS3 data-stream has a bit-rate of exactly 44.736Mbps
• The PTE will create 8000 STS-1 SPE’s per second
• In order to properly map a DS3 data-stream into an STS-1 data-stream, then each STS-1 SPE must carry
(44.736Mbps/8000 =) 5592 DS3 data bits.
Is there a Problem?
According to Figure 38, each STS-1 SPE only contains 5589 bits that are specifically designated for "DS3 data
bits". In this case, each STS-1 SPE appears to be three bits "short".
No there is a Simple Solution
No, earlier we mentioned that each STS-1 SPE consists of nine (9) "Stuff Opportunity" bits. Therefore, these
three additional bits (for DS3 data) are obtained by using three of these "Stuff Opportunity" bits. As a
consequence, three (3) of these nine (9) "Stuff Opportunity" bits, within each STS-1 SPE, will carry DS3 databits. The remaining six (6) "Stuff Opportunity" bits will typically function as "stuff" bits.
In summary, for the "Ideal Case"; where there is no frequency offset between the DS3 and the STS-1 bit-rates,
once this DS3 data-stream has been mapped into the STS-1 data-stream, then each and every STS-1 SPE will
have the following "Stuff Opportunity" bit utilization.
3 "Stuff Opportunity" bits will carry DS3 data bits.
6 "Stuff Opportunity" bits will function as "stuff" bits
In this case, this DS3 signal (which has now been mapped into STS-1) will be transported across the SONET
network. As this STS-1 signal arrives at the "Destination PTE", this PTE will extract (or de-map) this DS3 datastream from each incoming STS-1 SPE. Now since each and every STS-1 SPE contains exactly 5592 DS3
data bits; then the bit rate of this DS3 signal will be exactly 44.736Mbps (such as it was when it was mapped
into SONET, at the "Source" PTE).
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As a consequence, no "Mapping/De-Mapping" Jitter or Wander is induced in the "Ideal Case".
10.2.2.2
The 44.736Mbps + 1ppm Case
The "above example" was a very ideal case. In reality, there are going to be frequency offsets in both the DS3
and STS-1 signals. For instance Bellcore GR-499-CORE mandates that a DS3 signal have a bit rate of
44.736Mbps ± 20ppm. Hence, the bit-rate of a "Bellcore" compliant DS3 signal can vary from the exact correct
frequency for DS3 by as much of 20ppm in either direction. Similarly, many SONET applications mandate that
SONET equipment use at least a "Stratum 3" level clock as its timing source. This requirement mandates that
an STS-1 signal must have a bit rate that is in the range of 51.84 ± 4.6ppm. To make matters worse, there are
also provisions for SONET equipment to use (what is referred to as) a "SONET Minimum Clock" (SMC) as its
timing source. In this case, an STS-1 signal can have a bit-rate in the range of 51.84Mbps ± 20ppm.
In order to convey the impact that frequency offsets (in either the DS3 or STS-1 signal) will impose on the bitstuffing behavior, and the resulting bit-rate, intrinsic jitter and wander within the DS3 signal that is being
transported across the SONET network; let us assume that a DS3 signal, with a bit-rate of 44.736Mbps +
1ppm is being mapped into an STS-1 signal with a bit-rate of 51.84Mbps + 0ppm. In this case, the following
things will occur.
• In general, most of the STS-1 SPE's will each transport 5592 DS3 data bits.
• However, within a "one-second" period, a DS3 signal that has a bit-rate of 44.736Mbps + 1 ppm will deliver
approximately 44.7 additional bits (over and above that of a DS3 signal with a bit-rate of 44.736Mbps + 0
ppm). This means that this particular signal will need to "negative-stuff" or map in an additional DS3 data bit
every (1/44.736 =) 22.35ms. In other words, this additional DS3 data bit will need to be mapped into about
one in every (22.35ms · 8000 =) 178.8 STS-1 SPEs in order to avoid dropping any DS3 data-bits.
What does this mean at the "Source" PTE?
All of this means that as the "Source" PTE maps this DS3 signal, with a data rate of 44.736Mbps + 1ppm into
an STS-1 signal, most of the resulting "outbound" STS-1 SPEs will transport 5592 DS3 data bits (e.g., 3 Stuff
Opportunity bits will be carrying DS3 data bits, the remaining 6 Stuff Opportunity bits are "stuff" bits, as in the
"Ideal" case). However, in approximately one out of 178.8 "outbound" STS-1 SPEs, there will be a need to
insert an additional DS3 data bit within this STS-1 SPE. Whenever this occurs, then (for these particular STS1 SPEs) the SPE will be carrying 5593 DS3 data bits (e.g., 4 Stuff Opportunity bits will be carrying DS3 data
bits, the remaining 5 Stuff Opportunity bits are "stuff" bits).
Figure 40 presents an illustration of the STS-1 SPE traffic that will be generated by the "Source" PTE, during
this condition.
FIGURE 40. AN ILLUSTRATION OF THE STS-1 SPE TRAFFIC THAT WILL BE GENERATED BY THE "SOURCE" PTE,
WHEN MAPPING IN A DS3 SIGNAL THAT HAS A BIT RATE OF 44.736MBPS + 1PPM, INTO AN STS-1 SIGNAL
Extra DS3 Data
Bit Stuffed Here
SPE # N
Source
Source
PTE
PTE
5592
5592
DS3
DS3Data
Data
Bits
Bits
SPE # N+1
SPE # N+177
5592
5592
DS3
DS3Data
Data
Bits
Bits
5592
5592
DS3
DS3Data
Data
Bits
Bits
SPE # N+179
5593
5593
DS3
DS3Data
Data
Bits
Bits
SPE # N+178
44.736Mbps + 1ppm
STS-1 SPE Data Stream
100
5592
5592
DS3
DS3Data
Data
Bits
Bits
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What does this mean at the "Destination" PTE?
In this case, this DS3 signal (which has now been mapped into an STS-1 data-stream) will be transported
across the SONET network. As this STS-1 signal arrives at the "Destination" PTE, this PTE will extract (or demap) this DS3 data from each incoming STS-1 SPE. Now, in this case most (e.g., 177/178.8) of the incoming
STS-1 SPEs will contain 5592 DS3 data-bits. Therefore, the nominal data rate of the DS3 signal being demapped from SONET will be 44.736Mbps. However, in approximately 1 out of every 178 incoming STS-1
SPEs, the SPE will carry 5593 DS3 data-bits. This means that (during these times) the data rate of the demapped DS3 signal will have an instantaneous frequency that is greater than 44.736Mbps. These "excursion"
of the de-mapped DS3 data-rate, from the nominal DS3 frequency can be viewed as occurrences of "mapping/
de-mapping" jitter. Since each of these "bit-stuffing" events involve the insertion of one DS3 data bit, we can
say that the amplitude of this "mapping/de-mapping" jitter is approximately 1UI-pp. From this point on, we will
be referring to this type of jitter (e.g., that which is induced by the mapping and de-mapping process) as "demapping" jitter.
Since this occurrence of "de-mapping" jitter is periodic and occurs once every 22.35ms, we can state that this
jitter has a frequency of 44.7Hz.
10.2.2.3
The 44.736Mbps - 1ppm Case
In this case, let us assume that a DS3 signal, with a bit-rate of 44.736Mbps - 1ppm is being mapped into an
STS-1 signal with a bit-rate of 51.84Mbps + 0ppm. In this case, the following this will occur.
• In general, most of the STS-1 SPEs will each transport 5592 DS3 data bits.
• However, within a "one-second" period a DS3 signal that has a bit-rate of 44.736Mbps - 1ppm will deliver
approximately 45 too few bits below that of a DS3 signal with a bit-rate of 44.736Mbps + 0ppm. This means
that this particular signal will need to "positive-stuff" or exclude a DS3 data bit from mapping every (1/44.736)
= 22.35ms. In other words, we will need to avoid mapping this DS3 data-bit about one in every
(22.35ms*8000) = 178.8 STS-1 SPEs.
What does this mean at the "Source" PTE?
All of this means that as the "Source" PTE maps this DS3 signal, with a data rate of 44.736Mbps - 1ppm into
an STS-1 signal, most of the resulting "outbound" STS-1 SPEs will transport 5592 DS3 data bits (e.g., 3 Stuff
Opportunity bits will be carrying DS3 data bits, the remaining 6 Stuff Opportunity bits are "stuff" bits). However,
in approximately one out of 178.8 "outbound" STS-1 SPEs, there will be a need for a "positive-stuffing" event.
Whenever these "positive-stuffing" events occur then (for these particular STS-1 SPEs) the SPE will carry only
5591 DS3 data bits (e.g., in this case, only 2 Stuff Opportunity bits will be carrying DS3 data-bits, and the
remaining 7 Stuff Opportunity bits are "stuff" bits).
Figure 41 presents an illustration of the STS-1 SPE traffic that will be generated by the "Source" PTE, during
this condition.
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FIGURE 41. AN ILLUSTRATION OF THE STS-1 SPE TRAFFIC THAT WILL BE GENERATED BY THE SOURCE PTE, WHEN
MAPPING A DS3 SIGNAL THAT HAS A BIT RATE OF 44.736MBPS - 1PPM, INTO AN STS-1 SIGNAL
DS3 Data
Bit Excluded Here
SPE # N
Source
Source
PTE
PTE
5592
5592
DS3
DS3Data
Data
Bits
Bits
SPE # N+1
SPE # N+177
5592
5592
DS3
DS3Data
Data
Bits
Bits
5592
5592
DS3
DS3Data
Data
Bits
Bits
SPE # N+179
5591
5591
DS3
DS3Data
Data
Bits
Bits
5592
5592
DS3
DS3Data
Data
Bits
Bits
SPE # N+178
44.736Mbps - 1ppm
STS-1 SPE Data Stream
What does this mean at the Destination PTE?
In this case, this DS3 signal (which has now been mapped into an STS-1 data-stream) will be transported
across the SONET network. As this STS-1 signal arrives at the "Destination" PTE, this PTE will extract (or demap) this DS3 data from each incoming STS-1 SPE. Now, in this case, most (e.g., 177/178.8) of the incoming
STS-1 SPEs will contain 5592 DS3 data-bits. Therefore, the nominal data rate of the DS3 signal being demapped from SONET will be 44.736Mbps. However, in approximately 1 out of every 178 incoming STS-1
SPEs, the SPE will carry only 5591 DS3 data bits. This means that (during these times) the data rate of the demapped DS3 signal will have an instantaneous frequency that is less than 44.736Mbps. These "excursions" of
the de-mapped DS3 data-rate, from the nominal DS3 frequency can be viewed as occurrences of mapping/demapping jitter with an amplitude of approximately 1UI-pp.
Since this occurrence of "de-mapping" jitter is periodic and occurs once every 22.35ms, we can state that this
jitter has a frequency of 44.7Hz.
We talked about De-Mapping Jitter, What about De-Mapping Wander?
The Telcordia and Bellcore specifications define "Wander" as "Jitter with a frequency of less than 10Hz".
Based upon this definition, the DS3 signal (that is being transported by SONET) will cease to contain jitter and
will now contain "Wander", whenever the frequency offset of the DS3 signal being mapped into SONET is less
than 0.2ppm.
10.3
Jitter/Wander due to Pointer Adjustments
In the previous section, we described how a DS3 signal is asynchronously-mapped into SONET, and we also
defined "Mapping/De-mapping" jitter. In this section, we will describe how occurrences within the SONET
network will induce jitter/wander within the DS3 signal that is being transported across the SONET network.
In order to accomplish this, we will discuss the following topics in detail.
• The concept of an STS-1 SPE pointer
• The concept of Pointer Adjustments
• The causes of Pointer Adjustments
• How Pointer Adjustments induce jitter/wander within a DS3 signal being transported by that SONET network.
10.3.1
The Concept of an STS-1 SPE Pointer
As mentioned earlier, the STS-1 SPE is not aligned to the STS-1 frame boundaries and is permitted to "float"
within the Envelope Capacity. As a consequence, the STS-1 SPE will often times "straddle" across two
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consecutive STS-1 frames.
consecutive STS-1 frames.
Figure 42 presents an illustration of an STS-1 SPE straddling across two
FIGURE 42. AN ILLUSTRATION OF AN STS-1 SPE STRADDLING ACROSS TWO CONSECUTIVE STS-1 FRAMES
TOH
STS-1 FRAME N + 1
STS-1 FRAME N
H1, H2
Bytes
J1 Byte (1st byte of next SPE)
J1 Byte (1st byte of SPE)
SPE can straddle across two STS-1 frames
A PTE that is receiving and terminating an STS-1 data-stream will perform the following tasks.
• It will acquire and maintain STS-1 frame synchronization with the incoming STS-1 data-stream.
• Once the PTE has acquired STS-1 frame synchronization, then it will locate the J1 byte (e.g., the very byte
within the very next STS-1 SPE) within the Envelope Capacity by reading out the contents of the H1 and H2
bytes.
The H1 and H2 bytes are referred to (in the SONET standards) as the SPE Pointer Bytes. When these two
bytes are concatenated together in order to form a 16-bit word (with the H1 byte functioning as the "Most
Significant Byte") then the contents of the "lower" 10 bit-fields (within this 16-bit word) reflects the location of
the J1 byte within the Envelope Capacity of the incoming STS-1 data-stream. Figure 43 presents an
illustration of the bit format of the H1 and H2 bytes, and indicates which bit-fields are used to reflect the
location of the J1 byte.
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FIGURE 43. THE BIT-FORMAT OF THE 16-BIT WORD (CONSISTING OF THE H1 AND H2 BYTES) WITH THE 10 BITS,
J1 BYTE, DESIGNATED
REFLECTING THE LOCATION OF THE
H1 Byte
H2 Byte
MSB
LSB
N N N N S S X X X X X X X X X X
10 Bit Pointer Expression
Figure 44 relates the contents within these 10 bits (within the H1 and H2 bytes) to the location of the J1 byte
(e.g., the very first byte of the STS-1 SPE) within the Envelope Capacity.
FIGURE 44. THE RELATIONSHIP BETWEEN THE CONTENTS OF THE "POINTER BITS" (E.G., THE 10-BIT EXPRESSION
WITHIN THE H1 AND H2 BYTES) AND THE LOCATION OF THE J1 BYTE WITHIN THE ENVELOPE CAPACITY OF AN STS1 FRAME
TOH
A1
B1
D1
H1
B2
D4
D7
D10
S1
A2
E1
D2
H2
K1
D5
D8
D11
M0
The Pointer Value “0” is immediately
After the H3 byte
C1/J0
F1
D3
H3
K2
D6
D9
D12
E2
522
609
696
0
87
174
261
348
435
523
610
697
1
88
175
262
349
436
********
* * * ** ** * * *
* * * ** ** * * *
* * * ** ** * * *
* * * ** ** * * *
* * * ** ** * * *
* * * ** ** * * *
* * * ** ** * * *
* * * ** ** * * *
**
607
694
781
85
172
259
346
433
520
608
695
782
86
173
260
347
434
521
NOTES:
1. If the content of the "Pointer Bits" is "0x00" then the J1 byte is located immediately after the H3 byte, within the
Envelope Capacity.
2. If the contents of the 10-bit expression exceed the value of 0x30F (or 782, in decimal format) then it does not
contain a valid pointer value.
10.3.2
Pointer Adjustments within the SONET Network
The word SONET stands for "Synchronous Optical NETwork. This name implies that the entire SONET
network is synchronized to a single clock source. However, because the SONET (and SDH) Networks can
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span thousands of miles, traverse many different pieces of equipments, and even cross International
boundaries; in practice, the SONET/SDH network is NOT synchronized to a single clock source.
In practice, the SONET/SDH network can be thought of as being divided into numerous "Synchronization
Islands". Each of these "Synchronization Islands" will consist of numerous pieces of SONET Terminal
Equipment. Each of these pieces of SONET Terminal Equipment will all be synchronized to a single Stratum-1
clock source which is the most accurate clock source within the Synchronization Island. Typically a
"Synchronization Island" will consist of a single "Timing Master" equipment along with multiple "Timing Slave"
pieces of equipment. This "Timing Master" equipment will be directly connected to the Stratum-1 clock source
and will have the responsibility of distributing a very accurate clock signal (that has been derived from the
Stratum 1 clock source) to each of the "Timing Slave" pieces of equipment within the "Synchronization Island".
The purpose of this is to permit each of the "Timing Slave" pieces of equipment to be "synchronized" with the
"Timing Master" equipment, as well as the Stratum 1 Clock source. Typically this "clock distribution" is
performed in the form of a BITS (Building Integrated Timing Supply) clock, in which a very precise clock signal
is provided to the other pieces of equipment via a T1 or E1 line signal.
Many of these "Synchronization Islands" will use a Stratum-1" clock source that is derived from GPS pulses
that are received from Satellites that operate at Geo-synchronous orbit. Other "Synchronization Islands" will
use a Stratum-1" clock source that is derived from a very precise local atomic clock. As a consequence,
different "Synchronization Islands" will use different Stratum 1 clock sources. The up-shot of having these
"Synchronization Islands" that use different "Stratum-1 clock" sources, is that the Stratum 1 Clock frequencies,
between these "Synchronization Islands" are likely to be slightly different from each other. These "frequencydifferences" within Stratum 1 clock sources will result in "clock-domain changes" as a SONET signal (that is
traversing the SONET network) passes from one "Synchronization Island" to another.
The following section will describe how these "frequency differences" will cause a phenomenon called "pointer
adjustments" to occur in the SONET Network.
10.3.3
Causes of Pointer Adjustments
The best way to discuss how pointer adjustment events occur is to consider an STS-1 signal, which is driven by
a timing reference of frequency f1; and that this STS-1 signal is being routed to a network equipment (that
resides within a different "Synchronization Island") and processes STS-1 data at a frequency of f2.
NOTE: Clearly, both frequencies f1 and f2 are at the STS-1 rate (e.g., 51.84MHz). However, these two frequencies are
likely to be slightly different from each other.
Now, since the STS-1 signal (which is of frequency f1) is being routed to the network element (which is
operating at frequency f2), the typical design approach for handling "clock-domain" differences is to route this
STS-1 signal through a "Slip Buffer" as illustrated below.
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FIGURE 45. AN ILLUSTRATION OF AN STS-1 SIGNAL BEING PROCESSED VIA A SLIP BUFFER
Clock Domain operating
At frequency f1
STS-1 Data_IN
STS-1 Clock_f1
STS-1 Data_OUT
SLIP
SLIPBUFFER
BUFFER
STS-1 Clock_f2
Clock Domain operating
At Frequency f2.
In the "Slip Buffer, the "input" STS-1 data (labeled "STS-1 Data_IN") is latched into the FIFO, upon a given
edge of the corresponding "STS-1 Clock_f1" input clock signal. The STS-1 Data (labeled "STS-1 Data_OUT")
is clocked out of the Slip Buffer upon a given edge of the "STS-1 Clock_f2" input clock signal.
The behavior of the data, passing through the "Slip Buffer" is now described for each possible relationship
between frequencies f1 and f2.
If f1 = f2
If both frequencies, f1 and f2 are exactly equal, then the STS-1 data will be "clocked" into the "Slip Buffer" at
exactly the same rate that it is "clocked out". In this case, the "Slip Buffer" will neither fill-up nor become
depleted. As a consequence, no pointer-adjustments will occur in this STS-1 data stream. In other words, the
STS-1 SPE will remain at a constant location (or offset) within each STS-1 envelope capacity for the duration
that this STS-1 signal is supporting this particular service.
If f1 < f2
If frequency f1 is less than f2, then this means that the STS-1 data is being "clocked out" of the "Slip Buffer" at
a faster rate than it is being clocked in. In this case, the "Slip Buffer" will eventually become depleted.
Whenever this occurs, a typical strategy is to "stuff" (or insert) a "dummy byte" into the data stream. The
purpose of stuffing this "dummy byte" is to compensate for the frequency differences between f1 and f2, and
attempt to keep the "Slip Buffer, at a somewhat constant fill level.
NOTE: This "dummy byte" does not carry any valuable information (not for the user, nor for the system).
Since this "dummy byte" carries no useful information, it is important that the "Receiving PTE" be notified
anytime this "dummy byte" stuffing occurs. This way, the Receiving Terminal can "know" not to treat this
"dummy byte" as user data.
Byte-Stuffing and Pointer Incrementing in a SONET Network
Whenever this "byte-stuffing" occurs then the following other things occur within the STS-1 data stream.
During the STS-1 frame that contains the "Byte-Stuffing" event
a. The "stuff-byte" will be inserted into the byte position immediately after the H3 byte. This insertion of the
"dummy byte" immediately after the H3 byte position will cause the J1 byte (and in-turn, the rest of the
SPE) to be "byte-shifted" away from the H3 byte. As a consequence, the offset between the H3 byte position and the STS-1 SPE will now have been increased by 1 byte.
b. The "Transmitting" Network Equipment will notify the remote terminal of this byte-stuffing event, by inverting certain bits within the "pointer word" (within the H1 and H2 bytes) that are referred to as "I" bits.
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Figure 46 presents an illustration of the bit-format within the 16-bit word (consist of the H1 and H2 bytes) with
the "I" bits designated.
FIGURE 46. AN ILLUSTRATION OF THE BIT FORMAT WITHIN THE 16-BIT WORD (CONSISTING OF THE H1 AND H2
BYTES) WITH THE "I" BITS DESIGNATED
H1 Byte
H2 Byte
MSB
LSB
N N N N S S I D I D I D I D I D
10 Bit Pointer Expression
NOTE: At this time the "I" bits are inverted in order to denote that an "incrementing" pointer adjustment event is currently
occurring.
During the STS-1 frame that follows the "Byte-Stuffing" event
The "I" bits (within the "pointer-word") will be set back to their normal value; and the contents of the H1 and H2
bytes will be incremented by "1".
If f1 > f2
If frequency f1 is greater than f2, then this means that the STS-1 data is being clocked into the "Slip Buffer" at
a faster rate than is being clocked out. In this case, the "Slip Buffer" will start to fill up. Whenever this occurs, a
typical strategy is to delete (e.g., negative-stuff) a byte from the Slip Buffer. The purpose of this "negativestuffing" is to compensate for the frequency differences between f1 and f2; and to attempt to keep the "Slip
Buffer" at a somewhat constant fill-level.
NOTE: This byte, which is being "un-stuffed" does carry valuable information for the user (e.g., this byte is typically a
payload byte). Therefore, whenever this negative stuffing occurs, two things must happen.
a. The "negative-stuffed" byte must not be simply discarded. In other words, it must somehow also be
transmitted to the remote PTE with the remainder of the SPE data.
b. The remote PTE must be notified of the occurrence of these "negative-stuffing" events. Further, the
remote PTE must know where to obtain this "negative-stuffed" byte.
Negative-Stuffing and Pointer-Decrementing in a SONET Network
Whenever this "byte negative-stuffing" occurs then the following other things occur within the STS-1 datastream.
During the STS-1 frame that contains the "Negative Byte-Stuffing" Event
a. The "Negative-Stuffed" byte will be inserted into the H3 byte position. Whenever an SPE data byte is
inserted into the H3 byte position (which is ordinarily an unused byte), the number of bytes that will exist
between the H3 byte and the J1 byte within the very next SPE will be reduced by 1 byte. As a
consequence, in this case, the J1 byte (and in-turn, the rest of the SPE) will now be "byte-shifted"
towards the H3 byte position.
b. The "Transmitting" Network Element will notify the remote terminal of this "negative-stuff" event by
inverting certain bits within the "pointer word" (within the H1 and H2 bytes) that are referred to as "D"
bits.
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Figure 47 presents an illustration of the bit format within the 16-bit word (consisting of the H1 and H2 bytes)
with the "D" bits designated.
FIGURE 47. AN ILLUSTRATION OF THE BIT-FORMAT WITHIN THE 16-BIT WORD (CONSISTING OF THE H1 AND H2
"D" BITS DESIGNATED
BYTES) WITH THE
H1 Byte
H2 Byte
MSB
LSB
N N N N S S I D I D I D I D I D
10 Bit Pointer Expression
NOTE: At this time the "D" bits are inverted in order to denote that a "decrementing" pointer adjustment event is currently
occurring.
During the STS-1 frame that follows the "Negative Byte-Stuffing" Event
The "D" bits (within the pointer-word) will be set back to their normal value; and the contents of the H1 and H2
bytes will be decremented by one.
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Why are we talking about Pointer Adjustments?
The overall SONET network consists of numerous "Synchronization Islands". As a consequence, whenever a
SONET signal is being transmitted from one "Synchronization Island" to another; that SONET signal will
undergo a "clock domain" change as it traverses the network. This clock domain change will result in periodic
pointer-adjustments occurring within this SONET signal. Depending upon the direction of this "clock-domain"
shift that the SONET signal experiences, there will either be periodic "incrementing" pointer-adjustment events
or periodic "decrementing" pointer-adjustment events within this SONET signal.
Regardless of whether a given SONET signal is experiencing incrementing or decrementing pointer
adjustment events, each pointer adjustment event will result in an abrupt 8-bit shift in the position of the SPE
within the STS-1 data-stream. If this STS-1 signal is transporting an "asynchronously-mapped" DS3 signal;
then this 8-bit shift in the location of the SPE (within the STS-1 signal) will result in approximately 8UIpp of jitter
within the asynchronously-mapped DS3 signal, as it is de-mapped from SONET. In “Section 10.5, A Review of
the Category I Intrinsic Jitter Requirements (per Telcordia GR-253-CORE) for DS3 applications” on page 110
we will discuss the "Category I Intrinsic Jitter Requirements (for DS3 Applications) per Telcordia GR-253CORE. However, for now we will simply state that this 8UIpp of intrinsic jitter far exceeds these "intrinsic jitter"
requirements.
In summary, pointer-adjustments events are a "fact of life" within the SONET/SDH network. Further, pointeradjustment events, within a SONET signal that is transporting an asynchronously-mapped DS3 signal, will
impose a significant impact on the Intrinsic Jitter and Wander within that DS3 signal as it is de-mapped from
SONET.
10.4
Clock Gapping Jitter
In most applications (in which the XRT75R03D will be used in a SONET De-Sync Application) the user will
typically interface the XRT75R03D to a Mapper Device in the manner as presented below in Figure 48.
FIGURE 48. ILLUSTRATION OF THE TYPICAL APPLICATIONS FOR THE XRT75R03D IN A SONET DE-SYNC APPLICATION
De-Mapped (Gapped)
DS3 Data and Clock
TPDATA_n input pin
STS-N Signal
DS3totoSTS-N
STS-N
DS3
Mapper/
Mapper/
Demapper
Demapper
IC
IC
XRT75R03D
XRT75R03D
TCLK_n input
In this application, the Mapper IC will have the responsibility of receiving an STS-N signal (from the SONET
Network) and performing all of the following operations on this STS-N signal.
• Byte-de-interleaving this incoming STS-N signal into N STS-1 signals
• Terminating each of these STS-1 signals
• Extracting (or de-mapping) the DS3 signal(s) from the SPEs within each of these terminated STS-1 signals.
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In this application, these Mapper devices can be thought of as multi-channel devices. For example, an STS-3
Mapper can be viewed as a 3-Channel DS3/STS-1 to STS-3 Mapper IC. Similarly, an STS-12 Mapper can be
viewed as a 12-Channel DS3/STS-1 to STS-12 Mapper IC. Continuing on with this line of thought, if a Mapper
IC is configured to receive an STS-N signal, and (from this STS-N signal) de-map and output N DS3 signals
(towards the DS3 facility), then it will typically do so in the following manner.
• In many cases, the Mapper IC will output this DS3 signal, using both a "Data-Signal" and a "Clock-Signal". In
many cases, the Mapper IC will output the contents of an entire STS-1 data-stream via the Data-Signal.
• However, as the Mapper IC output this STS-1 data-stream, it will typically supply clock pulses (via the ClockSignal output) coincident to whenever a DS3 bit is being output via the Data-Signal. In this case, the Mapper
IC will NOT supply a clock pulse coincident to when a TOH, POH, or any "non-DS3 data-bit" is being output
via the "Data-Signal".
Now, since the Mapper IC will output the entire STS-1 data stream (via the Data-Signal), the output ClockSignal will be of the form such that it has a period of 19.3ns (e.g., a 51.84MHz clock signal). However, the
Mapper IC will still generate approximately 44,736,000 clock pulses during any given one second period.
Hence, the clock signal that is output from the Mapper IC will be a horribly gapped 44.736MHz clock signal.
One can view such a clock signal as being a very-jittery 44.736MHz clock signal. This jitter that exists within
the "Clock-Signal" is referred to as "Clock-Gapping" Jitter. A more detailed discussion on how the user must
handle this type of jitter is presented in “Section 10.8.2, Recommendations on Pre-Processing the Gapped
Clocks (from the Mapper/ASIC Device) prior to routing this DS3 Clock and Data-Signals to the Transmit Inputs
of the XRT75R03D” on page 121.
10.5
A Review of the Category I Intrinsic Jitter Requirements (per Telcordia GR-253-CORE) for DS3
applications
The "Category I Intrinsic Jitter Requirements" per Telcordia GR-253-CORE (for DS3 applications) mandates
that the user perform a large series of tests against certain specified "Scenarios". These "Scenarios" and their
corresponding requirements is summarized in Table 31, below.
TABLE 31: SUMMARY OF "CATEGORY I INTRINSIC JITTER REQUIREMENT PER TELCORDIA GR-253-CORE, FOR DS3
APPLICATIONS
SCENARIO
DESCRIPTION
SCENARIO
NUMBER
DS3 De-Mapping
Jitter
TELCORDIA GR-253-CORE
CATEGORY I INTRINSIC
JITTER REQUIREMENTS
COMMENTS
0.4UI-pp
Includes effects of De-Mapping and Clock Gapping Jitter
Single Pointer
Adjustment
A1
0.3UI-pp + Ao
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.NOTE: Ao is the amount
of intrinsic jitter that was measured during the "DS3 DeMapping Jitter" phase of the Test.
Pointer Bursts
A2
1.3UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
Phase Transients
A3
1.2UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
87-3 Pattern
A4
1.0UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
87-3 Add
A5
1.3UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
87-3 Cancel
A5
1.3UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
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TABLE 31: SUMMARY OF "CATEGORY I INTRINSIC JITTER REQUIREMENT PER TELCORDIA GR-253-CORE, FOR DS3
APPLICATIONS
SCENARIO
DESCRIPTION
SCENARIO
NUMBER
TELCORDIA GR-253-CORE
CATEGORY I INTRINSIC
JITTER REQUIREMENTS
Continuous Pattern
A4
1.0UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
Continuous Add
A5
1.3UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
Continuous Cancel
A5
1.3UI-pp
Includes effects of Jitter from Clock-Gapping, De-Mapping and Pointer Adjustments.
COMMENTS
NOTE: All of these intrinsic jitter measurements are to be performed using a band-pass filter of 10Hz to 400kHz.
Each of the scenarios presented in Table 31, are briefly described below.
10.5.1
DS3 De-Mapping Jitter
DS3 De-Mapping Jitter is the amount of Intrinsic Jitter that will be measured within the "Line" or "Facility-side"
DS3 signal, (after it has been de-mapped from a SONET signal) without the occurrence of "Pointer
Adjustments" within the SONET signal.
Telcordia GR-253-CORE requires that the "DS3 De-Mapping" Jitter be less than 0.4UI-pp, when measured
over all possible combinations of DS3 and STS-1 frequency offsets.
10.5.2
Single Pointer Adjustment
Telcordia GR-253-CORE states that if each pointer adjustment (within a continuous stream of pointer
adjustments) is separated from each other by a period of 30 seconds, or more; then they are sufficiently
isolated to be considered "Single-Pointer Adjustments".
Figure 49 presents an illustration of the "Single Pointer Adjustment" Scenario.
FIGURE 49. ILLUSTRATION OF SINGLE POINTER ADJUSTMENT SCENARIO
Pointer Adjustment Events
>30s
Initialization
Cool Down
Measurement Period
Telcordia GR-253-CORE states that the Intrinsic Jitter that is measured (within the DS3 signal) that is
ultimately de-mapped from a SONET signal that is experiencing "Single-Pointer Adjustment" events, must NOT
exceed the value 0.3UI-pp + Ao.
NOTES:
1. Ao is the amount of Intrinsic Jitter that was measured during the "De-Mapping" Jitter portion of this test.
2. Testing must be performed for both Incrementing and Decrementing Pointer Adjustments.
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10.5.3
REV. 1.0.2
Pointer Burst
Figure 50 presents an illustration of the "Pointer Burst" Pointer Adjustment Scenario per Telcordia GR-253CORE.
FIGURE 50. ILLUSTRATION OF BURST OF POINTER ADJUSTMENT SCENARIO
Pointer Adjustment Events
Pointer Adjustment Burst Train
t
0.5ms
0.5ms
>30s
Initialization
Cool Down
Measurement Period
Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "Burst of Pointer Adjustment" scenario, must NOT exceed 1.3UI-pp.
10.5.4
Phase Transients
Figure 51 presents an illustration of the "Phase Transients" Pointer Adjustment Scenario per Telcordia GR253-CORE.
FIGURE 51. ILLUSTRATION OF "PHASE-TRANSIENT" POINTER ADJUSTMENT SCENARIO
Pointer Adjustment Events
Pointer Adjustment Burst Train
0.5s
0.25s
0.25s
t
>30s
Initialization
Cool Down
Measurement Period
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Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "Phase Transient - Pointer Adjustment" scenario must NOT exceed
1.2UI-pp.
10.5.5
87-3 Pattern
Figure 52 presents an illustration of the "87-3 Continuous Pattern" Pointer Adjustment Scenario per Telcordia
GR-253-CORE.
FIGURE 52. AN ILLUSTRATION OF THE 87-3 CONTINUOUS POINTER ADJUSTMENT PATTERN
Repeating 87-3 Pattern (see below)
Pointer Adjustment Events
Initialization
Measurement Period
87-3 Pattern
87 Pointer Adjustment Events
No Pointer
Adjustments
NOTE: T ranges from 34ms to 10s (Req)
T ranges from 7.5ms to 34ms (Obj)
T
Telcordia GR-253-CORE defines an "87-3 Continuous" Pointer Adjustment pattern, as a repeating sequence of
90 pointer adjustment events. Within this 90 pointer adjustment event, 87 pointer adjustments are actually
executed. The remaining 3 pointer adjustments are never executed. The spacing between individual pointer
adjustment events (within this scenario) can range from 7.5ms to 10seconds.
Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "87-3 Continuous" pattern of Pointer Adjustments, must not exceed
1.0UI-pp.
10.5.6
87-3 Add
Figure 53 presents an illustration of the "87-3 Add Pattern" Pointer Adjustment Scenario per Telcordia GR-253CORE.
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REV. 1.0.2
FIGURE 53. ILLUSTRATION OF THE 87-3 ADD POINTER ADJUSTMENT PATTERN
Added Pointer Adjustment
No Pointer
Adjustments
43 Pointer Adjustments
T
43 Pointer Adjustments
t
Telcordia GR-253-CORE defines an "87-3 Add" Pointer Adjustment, as the "87-3 Continuous" Pointer
Adjustment pattern, with an additional pointer adjustment inserted, as shown above in Figure 53.
Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "87-3 Add" pattern of Pointer Adjustments, must not exceed 1.3UI-pp.
10.5.7
87-3 Cancel
Figure 54 presents an illustration of the 87-3 Cancel Pattern Pointer Adjustment Scenario per Telcordia GR253-CORE.
FIGURE 54. ILLUSTRATION OF 87-3 CANCEL POINTER ADJUSTMENT SCENARIO
86 or 87 Pointer Adjustments
No Pointer
Adjustments
T
Cancelled
Pointer Adjustment
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Telcordia GR-253-CORE defines an "87-3 Cancel" Pointer Adjustment, as the "87-3 Continuous" Pointer
Adjustment pattern, with an additional pointer adjustment cancelled (or not executed), as shown above in
Figure 54.
Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "87-3 Cancel" pattern of Pointer Adjustments, must not exceed 1.3UIpp.
10.5.8
Continuous Pattern
Figure 55 presents an illustration of the "Continuous" Pointer Adjustment Scenario per Telcordia GR-253CORE.
FIGURE 55. ILLUSTRATION OF CONTINUOUS PERIODIC POINTER ADJUSTMENT SCENARIO
Repeating Continuous Pattern (see below)
Pointer Adjustment Events
Initialization
Measurement Period
T
Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "Continuous" pattern of Pointer Adjustments, must not exceed 1.0UIpp. The spacing between individual pointer adjustments (within this scenario) can range from 7.5ms to 10s.
10.5.9
Continuous Add
Figure 56 presents an illustration of the "Continuous Add Pattern" Pointer Adjustment Scenario per Telcordia
GR-253-CORE.
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FIGURE 56. ILLUSTRATION OF CONTINUOUS-ADD POINTER ADJUSTMENT SCENARIO
Added Pointer Adjustment
Continuous Pointer Adjustments
T
Continuous Pointer Adjustments
t
Telcordia GR-253-CORE defines an "Continuous Add" Pointer Adjustment, as the "Continuous" Pointer
Adjustment pattern, with an additional pointer adjustment inserted, as shown above in Figure 56.
Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "Continuous Add" pattern of Pointer Adjustments, must not exceed
1.3UI-pp.
10.5.10
Continuous Cancel
Figure 57 presents an illustration of the "Continuous Cancel Pattern" Pointer Adjustment Scenario per
Telcordia GR-253-CORE.
FIGURE 57. ILLUSTRATION OF CONTINUOUS-CANCEL POINTER ADJUSTMENT SCENARIO
Continuous Pointer Adjustments
T
Cancelled
Pointer Adjustment
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REV. 1.0.2
Telcordia GR-253-CORE defines a "Continuous Cancel" Pointer Adjustment, as the "Continuous" Pointer
Adjustment pattern, with an additional pointer adjustment cancelled (or not executed), as shown above in
Figure 57.
Telcordia GR-253-CORE mandates that the Intrinsic Jitter, within the DS3 signal that is de-mapped from a
SONET signal, which is experiencing the "Continuous Cancel" pattern of Pointer Adjustments, must not exceed
1.3UI-pp.
A Review of the DS3 Wander Requirements per ANSI T1.105.03b-1997.
10.6
To be provided in the next revision of this data sheet.
10.7
A Review of the Intrinsic Jitter and Wander Capabilities of the XRT75R03D in a typical system
application
The Intrinsic Jitter and Wander Test results are summarized in this section.
10.7.1
Intrinsic Jitter Test results
The Intrinsic Jitter Test results for the XRT75R03D in DS3 being de-mapped from SONET is summarized
below in Table 2.
TABLE 32: SUMMARY OF "CATEGORY I INTRINSIC JITTER TEST RESULTS" FOR SONET/DS3 APPLICATIONS
SCENARIO
DESCRIPTION
SCENARIO
NUMBER
DS3 De-Mapping
Jitter
XRT75R03D
INTRINSIC JITTER TEST RESULTS
TELCORDIA GR-253-CORE CATEGORY I
INTRINSIC JITTER REQUIREMENTS
0.13UI-pp
0.4UI-pp
Single Pointer
Adjustment
A1
0.201UI-pp
0.43UI-pp (e.g. 0.13UI-pp + 0.3UI-pp)
Pointer Bursts
A2
0.582UI-pp
1.3UI-pp
Phase Transients
A3
0.526UI-pp
1.2UI-pp
87-3 Pattern
A4
0.790UI-pp
1.0UI-pp
87-3 Add
A5
0.926UI-pp
1.3UI-pp
87-3 Cancel
A5
0.885UI-pp
1.3UI-pp
Continuous
Pattern
A4
0.497UI-pp
1.0UI-pp
Continuous Add
A5
0.598UI-pp
1.3UI-pp
Continuous
Cancel
A5
0.589UI-pp
1.3UI-pp
NOTES:
1. A detailed test report on our Test Procedures and Test Results is available and can be obtained by contacting your
Exar Sales Representative.
2. These test results were obtained via the XRT75R03Ds mounted on our XRT94L43 12-Channel DS3/E3/STS-1
Mapper Evaluation Board.
3. These same results apply to SDH/AU-3 Mapping applications.
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10.7.2
REV. 1.0.2
Wander Measurement Test Results
Wander Measurement test results will be provided in the next revision of the XRT75R03D Data Sheet.
10.8
Designing with the XRT75R03D
In this section, we will discuss the following topics.
• How to design with and configure the XRT75R03D to permit a system to meet the above-mentioned Intrinsic
Jitter and Wander requirements.
• How is the XRT75R03D able to meet the above-mentioned requirements?
• How does the XRT75R03D permits the user to comply with the SONET APS Recovery Time requirements of
50ms (per Telcordia GR-253-CORE)?
• How should one configure the XRT75R03D, if one needs to support "Daisy-Chain" Testing at the end
Customer’s site?
10.8.1
How to design and configure the XRT75R03D to permit a system to meet the abovementioned Intrinsic Jitter and Wander requirements
As mentioned earlier, in most application (in which the XRT75R03D will be used in a SONET De-Sync
Application) the user will typically interface the XRT75R03D to a Mapper device in the manner as presented
below in Figure 58.
In this application, the Mapper has the responsibility of receiving a SONET STS-N/OC-N signal and extracting
as many as N DS3 signals from this signal. As a given channel within the Mapper IC extracts out a given DS3
signal (from SONET) it will typically be applying a Clock and Data signal to the "Transmit Input" of the LIU IC.
Figure 58 presents a simple illustration as to how one channel, within the XRT75R03D should be connected to
the Mapper IC.
FIGURE 58. ILLUSTRATION OF THE XRT75R03D BEING CONNECTED TO A MAPPER IC FOR SONET DE-SYNC
APPLICATIONS
De-Mapped (Gapped)
DS3 Data and Clock
TPDATA_n input pin
STS-N Signal
DS3to
toSTS-N
STS-N
DS3
Mapper/
Mapper/
Demapper
Demapper
IC
IC
XRT75R03D
XRT75R03D
TCLK_n input
As mentioned above, the Mapper IC will typically output a Clock and Data signal to the XRT75R03D. In many
cases, the Mapper IC will output the contents of an entire STS-1 data-stream via the Data Signal to the
XRT75R03D. However, the Mapper IC typically only supplies a clock pulse via the Clock Signal to the
XRT75R03D coincident to whenever a DS3 bit is being output via the Data Signal. In this case, the Mapper IC
would not supply a clock edge coincident to when a TOH, POH or any non-DS3 data-bit is being output via the
Data-Signal.
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Figure 58 indicates that the Data Signal from the Mapper device should be connected to the TPDATA_n input
pin of the LIU IC and that the Clock Signal from the Mapper device should be connected to the TCLK_n input
pin of the LIU IC.
In this application, the XRT75R03D has the following responsibilities.
• Using a particular clock edge within the "gapped" clock signal (from the Mapper IC) to sample and latch the
value of each DS3 data-bit that is output from the Mapper IC.
• To (through the user of the Jitter Attenuator block) attenuate the jitter within this "DS3 data" and "clock signal"
that is output from the Mapper IC.
• To convert this "smoothed" DS3 data and clock into industry-compliant DS3 pulses, and to output these
pulses onto the line.
To configure the XRT75R03D to operate in the correct mode for this application, the user must execute the
following configuration steps.
a. Configure the XRT75R03D to operate in the DS3 Mode
The user can configure a given channel (within the XRT75R03D) to operate in the DS3 Mode, by executing
either of the following steps.
• If the XRT75R03D has been configured to operate in the Host Mode
The user can accomplish this by setting both Bits 2 (E3_n) and Bits 1 (STS-1/DS3*_n), within each of the
"Channel Control Registers" to "0" as depicted below.
CHANNEL CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X06
CHANNEL 1 ADDRESS LOCATION = 0X0E
CHANNEL 2 ADDRESS LOCATION = 0X16
BIT 7
BIT 6
Unused
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
PRBS Enable
Ch_n
RLB_n
LLB_n
E3_n
STS-1/DS3_n
SR/DR_n
R/O
R/O
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
• If the XRT75R03D has been configured to operate in the Hardware Mode
The user can accomplish this by pulling all of the following input pins "Low".
Pin 76 - E3_0
Pin 94 - E3_1
Pin 85 - E3_2
Pin 72 - STS-1/DS3_0
Pin 98 - STS-1/DS3_1
Pin 81 - STS-1/DS3_2
b. Configure the XRT75R03D to operate in the Single-Rail Mode
Since the Mapper IC will typically output a single "Data Line" and a "Clock Line" for each DS3 signal that it
demaps from the incoming STS-N signal, it is imperative to configure each channel within the XRT75R03D to
operate in the Single Rail Mode.
The user can accomplish this by executing either of the following steps.
• If the XRT75R03D has been configured to operate in the Host Mode
The user can accomplish this by setting Bit 0 (SR/DR*), within the each of the "Channel Control" Registers to 1,
as illustrated below.
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CHANNEL CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X06
CHANNEL 1 ADDRESS LOCATION = 0X0E
CHANNEL 2 ADDRESS LOCATION = 0X16
BIT 7
BIT 6
Unused
BIT 5
BIT 4
BIT 3
BIT 2
PRBS Enable
Ch_n
RLB_n
LLB_n
E3_n
BIT 1
BIT 0
STS-1/
SR/DR_n
DS3_n
R/O
R/O
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
1
• If the XRT75R03D has been configured to operate in the Hardware Mode
Then the user should tie pin 65 (SR/DR*) to "High".
c. Configure each of the three channels within the XRT75R03D to operate in the SONET De-Sync
Mode
The user can accomplish this by executing either of the following steps.
• If the XRT75R03D has been configured to operate in the Host Mode.
Then the user should set Bit D2 (JA0) to "0" and Bit D0 (JA1) to "1", within the Jitter Attenuator Control
Register, as depicted below.
JITTER ATTENUATOR CONTROL REGISTER - (CHANNEL 0 ADDRESS LOCATION = 0X07
CHANNEL 1 ADDRESS LOCATION = 0X0F
CHANNEL 2 ADDRESS LOCATION = 0X17
BIT 7
BIT 6
BIT 5
Unused
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SONET APS
Recovery
Time
DisableCh_n
JA RESET
Ch_n
JA1 Ch_n
JA in Tx Path
Ch_n
JA0 Ch_n
R/O
R/O
R/O
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
1
• If the XRT75R03D has been configured to operate in the Hardware Mode
Then the user should tie pin 44 (JA0) to a logic "HIGH" and pin 42 (JA1) to a logic "LOW".
Once the user accomplishes either of these steps, then the Jitter Attenuator (within the XRT75R03D) will be
configured to operate with a very narrow bandwidth.
d. Configure the Jitter Attenuator (within each of three three channels) to operate in the Transmit
Direction.
The user can accomplish this by executing either the following steps.
• If the XRT75R03D has been configured to operate in the Host Mode.
Then the user should be Bit D1 (JATx/JARx*) to "1", within the Jitter Attenuator Control Register, as depicted
below.
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JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07
CHANNEL 1 ADDRESS LOCATION = 0X0F
CHANNEL 2 ADDRESS LOCATION = 0X17
BIT 7
BIT 6
BIT 5
Unused
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SONET APS
Recovery
Time
DisableCh_n
JA RESET
Ch_n
JA1 Ch_n
JA in Tx Path
Ch_n
JA0 Ch_n
R/O
R/O
R/O
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
1
1
• If the XRT75R03D has been configured to operate in the Hardware Mode.
Then the user should tie pin 43 (JATx/JARx*) to "1".
e. Enable the "SONET APS Recovery Time" Mode
Finally, if the user intends to use the XRT75R03D in an Application that is required to reacquire proper SONET
and DS3 traffic, prior within 50ms of an APS (Automatic Protection Switching) event (per Telcordia GR-253CORE), then the user should set Bit 4 (SONET APS Recovery Time Disable), within the "Jitter Attenuator
Control" Register, to "0" as depicted below.
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07
CHANNEL 1 ADDRESS LOCATION = 0X0F
CHANNEL 2 ADDRESS LOCATION = 0X17
BIT 7
BIT 6
BIT 5
Unused
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SONET APS
Recovery
Time
DisableCh_n
JA RESET
Ch_n
JA1 Ch_n
JA in Tx Path
Ch_n
JA0 Ch_n
R/O
R/O
R/O
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
1
NOTES:
1. The ability to disable the "SONET APS Recovery Time" mode is only available if the XRT75R03D is operating in
the Host Mode. If the XRT75R03D is operating in the "Hardware" Mode, then this "SONET APS Recovery Time
Mode" feature will always be enabled.
2. The "SONET APS Recovery Time" mode will be discussed in greater detail in “Section 10.8.3, How does the
XRT75R03D permit the user to comply with the SONET APS Recovery Time requirements of 50ms (per Telcordia
GR-253-CORE)?” on page 125.
10.8.2
Recommendations on Pre-Processing the Gapped Clocks (from the Mapper/ASIC Device)
prior to routing this DS3 Clock and Data-Signals to the Transmit Inputs of the XRT75R03D
In order to minimize the effects of "Clock-Gapping" Jitter within the DS3 signal that is ultimately transmitted to
the DS3 Line (or facility), we recommend that some "pre-processing" of the "Data-Signals" and "Clock-Signals"
(which are output from the Mapper device) be implemented prior to routing these signals to the "Transmit
Inputs" of the XRT75R03D.
10.8.2.1
SOME NOTES PRIOR TO STARTING THIS DISCUSSION:
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Our simulation results indicate that Jitter Attenuator PLL (within the XRT75R03D LIU IC) will have no problem
handling and processing the "Data-Signal" and "Clock-Signal" from a Mapper IC/ASIC if no pre-processing has
been performed on these signals. In order words, our simulation results indicate that the Jitter Attenuator PLL
(within the LIU IC) will have no problem handling the "worst-case" of 59 consecutive bits of no clock pulses in
the "Clock-Signal (due to the Mapper IC processing the TOH bytes, an Incrementing Pointer-Adjustmentinduced "stuffed-byte", the POH byte, and the two fixed-stuff bytes within the STS-1 SPE, etc), immediately
followed be processing clusters of DS3 data-bits (as shown in Figure 38) and still comply with the "Category I
Intrinsic Jitter Requirements per Telcordia GR-253-CORE for DS3 applications.
NOTE: If this sort of "pre-processing" is already supported by the Mapper device that you are using, then no further action
is required by the user.
10.8.2.2
OUR PRE-PROCESSING RECOMMENDATIONS
For the time-being, we recommend that the customer implement the "pre-processing" of the DS3 "Data-Signal"
and "Clock-Signal" as described below. Currently we are aware that some of the Mapper products on the
Market do implement this exact "pre-processing" algorithm. However, if the customer is implementing their
Mapper Design in an ASIC or FPGA solution, then we strongly recommend that the user implement the
necessary logic design to realize the following recommendations.
Some time ago, we spent some time, studying (and then later testing our solution with) the PM5342 OC-3 to
DS3 Mapper IC from PMC-Sierra. In particular, we wanted to understand the type of "DS3 Clock" and "Data"
signal that this DS3 to OC-3 Mapper IC outputs.
During this effort, we learned the following.
1.
This "DS3 Clock" and "Data" signal, which is output from the Mapper IC consists of two major "repeating"
patterns (which we will refer to as "MAJOR PATTERN A" and "MAJOR PATTERN B". The behavior of
each of these patterns is presented below.
MAJOR PATTERN A
MAJOR PATTERN A consists of two "sub" or minor-patterns, (which we will refer to as "MINOR PATTERN P1
and P2).
MINOR PATTERN P1 consists of a string of seven (7) clock pulses, followed by a single gap (no clock pulse).
An illustration of MINOR PATTERN P1 is presented below in Figure 59.
FIGURE 59. ILLUSTRATION OF MINOR PATTERN P1
Missing Clock Pulse
1
2
3
4
5
6
7
It should be noted that each of these clock pulses has a period of approximately 19.3ns (or has an
"instantaneously frequency of 51.84MHz).
MINOR Pattern P2 consists of string of five (5) clock pulses, which is also followed by a single gap (no clock
pulse). An illustration of Pattern P2 is presented below in Figure 60.
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FIGURE 60. ILLUSTRATION OF MINOR PATTERN P2
Missing Clock Pulse
1
2
3
4
5
HOW MAJOR PATTERN A IS SYNTHESIZED
MAJOR PATTERN A is created (by the Mapper IC) by:
• Repeating MINOR PATTERN P1 (e.g., 7 clock pulses, followed by a gap) 63 times.
• Upon completion of the 63rd transmission of MINOR PATTERN P1, MINOR PATTERN P2 is transmitted
repeatedly 36 times.
Figure 61 presents an illustration which depicts the procedure that is used to synthesize MAJOR PATTERN A
FIGURE 61. ILLUSTRATION OF PROCEDURE WHICH IS USED TO SYNTHESIZE MAJOR PATTERN A
Repeats 63 Times
MINOR PATTERN P1
Repeats 36 Times
MINOR PATTERN P2
Hence, MAJOR PATTERN A consists of "(63 x 7) + (36 x 5)" = 621 clock pulses. These 621 clock pulses were
delivered over a period of "(63 x 8) + (36 x 6)" = 720 STS-1 (or 51.84MHz) clock periods.
MAJOR PATTERN B
MAJOR PATTERN B consists of three sub or minor-patterns (which we will refer to as "MINOR PATTERNS P1,
P2 and P3).
MINOR PATTERN P1, which is used to partially synthesize MAJOR PATTERN B, is exactly the same "MINOR
PATTERN P1" as was presented above in Figure 31. Similarly, the MINOR PATTERN P2, which is also used
to partially synthesize MAJOR PATTERN B, is exactly the same "MINOR PATTERN P2" as was presented in
Figure 32.
MINOR PATTERN P3 (which has yet to be defined) consists of a string of six (6) clock pulses, which contains
no gaps. An illustration of MINOR PATTERN P3 is presented below in Figure 62.
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FIGURE 62. ILLUSTRATION OF MINOR PATTERN P3
1
2
3
4
5
6
HOW MAJOR PATTERN B IS SYNTHESIZED
MAJOR PATTERN B is created (by the Mapper IC) by:
• Repeating MINOR PATTERN P1 (e.g., 7 clock pulses, followed by a gap) 63 times.
• Upon completion of the 63rd transmission of MINOR PATTERN P1, MINOR PATTERN P2 is transmitted
repeatedly 36 times.
• pon completion of the 35th transmission of MINOR PATTERN P2, MINOR PATTERN P3 is transmitted once.
Figure 63 presents an illustration which depicts the procedure that is used to synthesize MAJOR PATTERN B.
FIGURE 63. ILLUSTRATION OF PROCEDURE WHICH IS USED TO SYNTHESIZE PATTERN B
Transmitted 1 Time
Repeats 63 Times
PATTERN P1
Repeats 35 Times
PATTERN P2
PATTERN P3
Hence, MAJOR PATTERN B consists of "(63 x 7) + (35 x 5)" + 6 = 622 clock pulses.
These 622 clock pulses were delivered over a period of "(63 x 8) + (35 x 6) + 6 = 720 STS-1 (or 51.84MHz)
clock periods.
PUTTING THE PATTERNS TOGETHER
Finally, the DS3 to OC-N Mapper IC clock output is reproduced by doing the following.
• MAJOR PATTERN A is transmitted two times (repeatedly).
• After the second transmission of MAJOR PATTERN A, MAJOR PATTERN B is transmitted once.
• Then the whole process repeats.
Throughout the remainder of this document, we will refer to this particular pattern as the "SUPER PATTERN".
Figure 64 presents an illustration of this "SUPER PATTERN" which is output via the Mapper IC.
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FIGURE 64. ILLUSTRATION OF THE SUPER PATTERN WHICH IS OUTPUT VIA THE "OC-N TO DS3" MAPPER IC
PATTERN A
PATTERN A
PATTERN B
CROSS-CHECKING OUR DATA
• Each SUPER PATTERN consists of (621 + 621 + 622) = 1864 clock pulses.
• The total amount of time, which is required for the "DS3 to OC-N Mapper" IC to transmit this SUPER
PATTERN is (720 + 720 + 720) = 2160 "STS-1" clock periods.
• This amount to a period of (2160/51.84MHz) = 41,667ns.
• In a period of 41, 667ns, the XRT75R03D (when configured to operate in the DS3 Mode), will output a total
(41,667ns x 44,736,000) = 1864 uniformly spaced DS3 clock pulses.
• Hence, the number of clock pulses match.
APPLYING THE SUPER PATTERN TO THE XRT75R03D
Whenever the XRT75R03D is configured to operate in a "SONET De-Sync" application, the device will accept
a continuous string of the above-defined SUPER PATTERN, via the TCLK input pin (along with the
corresponding data). The channel within the XRT75R03D (which will be configured to operate in the "DS3"
Mode) will output a DS3 line signal (to the DS3 facility) that complies with the "Category I Intrinsic Jitter
Requirements - per Telcordia GR-253-CORE (for DS3 applications). This scheme is illustrated below in Figure
65.
FIGURE 65. SIMPLE ILLUSTRATION OF THE XRT75R03D BEING USED IN A SONET DE-SYNCHRONIZER" APPLICATION
De-Mapped (Gapped)
DS3 Data and Clock
TPDATA_n input pin
STS-N Signal
DS3to
toSTS-N
STS-N
DS3
Mapper/
Mapper/
Demapper
Demapper
IC
IC
XRT75R03D
XRT75R03D
TCLK_n input
10.8.3
How does the XRT75R03D permit the user to comply with the SONET APS Recovery Time
requirements of 50ms (per Telcordia GR-253-CORE)?
Telcordia GR-253-CORE, Section 5.3.3.3 mandates that the "APS Completion" (or Recovery) time be 50ms or
less. Many of our customers interpret this particular requirement as follows.
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XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
"From the instant that an APS is initiated on a high-speed SONET signal, all lower-speed SONET traffic (which
is being transported via this "high-speed" SONET signal) must be fully restored within 50ms. Similarly, if the
"high-speed" SONET signal is transporting some PDH signals (such as DS1 or DS3, etc.), then those entities
that are responsible for acquiring and maintaining DS1 or DS3 frame synchronization (with these DS1 or DS3
data-streams that have been de-mapped from SONET) must have re-acquired DS1 or DS3 frame
synchronization within 50ms" after APS has been initiated."
The XRT75R03D was designed such that the DS3 signals that it receives from a SONET Mapper device and
processes will comply with the Category I Intrinsic Jitter requirements per Telcordia GR-253-CORE.
Reference 1 documents some APS Recovery Time testing, which was performed to verify that the Jitter
Attenuator blocks (within the XRT75R03D) device that permit it to comply with the Category I Intrinsic Jitter
Requirements (for DS3 Applications) per Telcordia GR-253-CORE, do not cause it to fail to comply with the
"APS Completion Time" requirements per Section 5.3.3.3 of Telcordia GR-253-CORE. However, Table 3
presents a summary of some APS Recovery Time requirements that were documented within this test report.
Table 3,
TABLE 33: MEASURED APS RECOVERY TIME AS A FUNCTION OF DS3 PPM OFFSET
DS3 PPM OFFSET (PER W&G ANT-20SE)
MEASURED APS RECOVERY TIME (PER LOGIC ANALYZER)
-99 ppm
1.25ms
-40ppm
1.54ms
-30 ppm
1.34ms
-20 ppm
1.49ms
-10 ppm
1.30ms
0 ppm
1.89ms
+10 ppm
1.21ms
+20 ppm
1.64ms
+30 ppm
1.32ms
+40 ppm
1.25ms
+99 ppm
1.35ms
NOTE: The APS Completion (or Recovery) time requirement is 50ms.
Configuring the XRT75R03D to be able to comply with the SONET APS Recovery Time Requirements of
50ms
Quite simply, the user can configure a given Jitter Attenuator block (associated with a given channel) to (1)
comply with the "APS Completion Time" requirements per Telcordia GR-253-CORE, and (2) also comply with
the "Category I Intrinsic Jitter Requirements per Telcordia GR-253-CORE (for DS3 applications) by making
sure that Bit 4 (SONET APS Recovery Time Disable Ch_n), within the Jitter Attenuator Control Register is set
to "0" as depicted below.
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XRT75R03D
REV. 1.0.2
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07
CHANNEL 1 ADDRESS LOCATION = 0X0F
CHANNEL 2 ADDRESS LOCATION = 0X17
BIT 7
BIT 6
BIT 5
Unused
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SONET APS
Recovery
Time Disable
Ch_n
JA RESET
Ch_n
JA1 Ch_n
JA in Tx Path
Ch_n
JA0 Ch_n
R/O
R/O
R/O
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
1
1
NOTE: The user can only disable the "SONET APS Recovery Time Mode" if the XRT75R03D is operating in the Host
Mode. If the user is operating the XRT75R03D in the Hardware Mode, then the user will have NO ability to disable
the "SONET APS Recovery Time Mode" feature.
10.8.4
How should one configure the XRT75R03D, if one needs to support "Daisy-Chain" Testing at
the end Customer’s site?
Daisy-Chain testing is emerging as a new requirements that many of our customers are imposing on our
SONET Mapper and LIU products. Many System Designer/Manufacturers are finding out that whenever their
end-customers that are evaluating and testing out their systems (in order to determine if they wish to move
forward and start purchasing this equipment in volume) are routinely demanding that they be able to test out
these systems with a single piece of test equipment. This means that the end-customer would like to take a
single piece of DS3 or STS-1 test equipment and (with this test equipment) snake the DS3 or STS-1 traffic
(that this test equipment will generate) through many or (preferably all) channels within the system. For
example, we have had request from our customers that (on a system that supports OC-192) our silicon be able
to support this DS3 or STS-1 traffic snaking through the 192 DS3 or STS-1 ports within this system.
After extensive testing, we have determined that the best approach to complying with test "Daisy-Chain"
Testing requirements, is to configure the Jitter Attenuator blocks (within each of the Channels within the
XRT75R03D) into the "32-Bit" Mode. The user can configure the Jitter Attenuator block (within a given channel
of the XRT75R03D) to operate in this mode by settings in the table below.
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07
CHANNEL 1 ADDRESS LOCATION = 0X0F
CHANNEL 2 ADDRESS LOCATION = 0X17
BIT 7
BIT 6
BIT 5
Unused
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SONET APS
Recovery
Time Disable
Ch_n
JA RESET
Ch_n
JA1 Ch_n
JA in Tx Path
Ch_n
JA0 Ch_n
R/O
R/O
R/O
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
1
1
0
REFERENCES
1. TEST REPORT - AUTOMATIC PROTECTION SWITCHING (APS) RECOVERY TIME TESTING WITH THE
XRT94L43 DS3/E3/STS-1 TO STS-12 MAPPER IC - Revision C Silicon
127
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
ORDERING INFORMATION
PART NUMBER
PACKAGE
OPERATING TEMPERATURE RANGE
XRT75R03DIV
14 x 20 mm 128 Pin LQFP
- 40°C to + 85°C
PACKAGE DIMENSIONS - 14X20 MM, 128 PIN PACKAGE
D
D1
102
65
103
64
E1
128
39
A2
1
38
B
e
A
α
C
A1
N o te : T h e c o n tro l d im e n s io n s a re th e m illim e te r c o lu m n
T h e H e a t S lu g is a t th e c e n te r o f th e p a c k a g e .
IN C H E S
L
M IL L IM E T E R S
S YM B O L
M IN
MAX
M IN
MAX
A
0 .0 5 5
0 .0 6 3
1 .4 0
1 .6 0
A1
0 .0 0 2
0 .0 0 6
0 .0 5
0 .1 5
A2
0 .0 5 3
0 .0 5 7
1 .3 5
1 .4 5
B
0 .0 0 7
0 .0 1 1
0 .1 7
0 .2 7
C
0 .0 0 4
0 .0 0 8
0 .0 9
0 .2 0
D
0 .8 5 8
0 .8 7 4
2 1 .8 0
2 2 .2 0
D1
0 .7 8 3
0 .7 9 1
1 9 .9 0
2 0 .1 0
E
0 .6 2 2
0 .6 3 8
1 5 .8 0
1 6 .2 0
E1
0 .5 4 7
0 .5 5 5
1 3 .9 0
1 4 .1 0
e
0 .0 2 0 B S C
0 .5 0 B S C
L
0 .0 1 8
0 .0 3 0
0 .4 5
0 .7 5
α
0o
7o
0o
7o
128
XRT75R03D
THREE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCRONIZER
REV. 1.0.2
REVISIONS
REVISION
DATE
COMMENTS
1.0.0
06/03
Initial issue
1.0.1
08/03
Changed XRT75VL03 to XRT75R03. Added R3 Technology description.
1.0.2
12/03
Changed the pin description for E3Clk/Clk_en and STS-1Clk/12M. Removed page 18 (redundant page). Changed the Enable to Status in Register 0x21h.
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to
improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any
circuits described herein, conveys no license under any patent or other right, and makes no representation that
the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration
purposes and may vary depending upon a user’s specific application. While the information in this publication
has been carefully checked; no responsibility, however, is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the
failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to
significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless
EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has
been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately
protected under the circumstances.
Copyright 2003 EXAR Corporation
Datasheet December 2003.
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
129