CS61577
T1/E1 Line Interface
Features
General Description
•
The CS61577 is a drop-in replacement for the
CS61574, and combines the complete analog transmit
and receive line interface for T1 or E1 applications in a
low power, 28-pin device operating from a +5V supply.
The CS61577 supports processor-based or standalone operation and interfaces with industry standard
T1 and E1 framers.
The receiver uses a digital Delay-Locked-Loop which is
continuously calibrated from a crystal reference to provide excellent stability and jitter tolerance. The receiver
includes a jitter attenuator optimized for minimum delay
in switching and transmission applications. The transmitter provides internal pulse shaping to insure
compliance with T1 and E1 pulse template specifications.
Provides Analog Transmission Line
Interface for T1 and E1 Applications
• Drop-in Replacement for CS61574 with
the Following Enhancements:
- Lower Power Consumption
-
Transmitter Short-Circuit
Current Limiting
-
Greater Transmitter Immunity
to Line Reflections
Applications
-
Software Selection Between 75Ω and
120Ω E1 Output Options
-
Internally Controlled E1 Pulse Width
-
B8ZS/HDB3/AMI Encoder/Decoder
( ) = Pin Function in Host Mode
[ ] = Pin Function in Extended Hardware Mode
2
TPOS
[TDATA]
TNEG
[TCODE]
RCLK
RPOS
[RDATA]
RNEG
[BPV]
3
4
8
AMI,
B8ZS,
HDB3,
CODER
L
O
O
P
B
A
C
K
7
6
Interfacing Network Equipment such as DACS and
Channel Banks to a DSX-1 Cross Connect
•
Building Channel Service Units
ORDERING INFORMATION
CS61577-IP1
28 Pin Plastic DIP
CS61577-IL1
28 Pin Plastic PLCC
MODE
(CLKE) (INT) (SDI) (SDO)
TAOS LEN0 LEN1 LEN2
5
R
E
M
O
T
E
TCLK
•
L
O
C
A
L
28
24
25
TV+
15
14
LINE DRIVER
13
PULSE
SHAPER
CONTROL
16
LINE RECEIVER
L
O
O
P
B
A
C
K
JITTER
ATTENUATOR
23
TGND
CLOCK &
DATA
RECOVERY
19
20
17
SIGNAL
QUALITY
MONITOR
DRIVER
MONITOR
18
11
26
9
10
1
RLOOP XTALIN XTALOUT ACLKI
(CS)
Preliminary Product Information
Crystal Semiconductor Corporation
P. O. Box 17847, Austin, Texas, 78760
(512) 445-7222 FAX:(512) 445-7581
27
LLOOP
(SCLK)
12
LOS
21
RV+
22
TTIP
TRING
RTIP
RRING
MTIP
[RCODE]
MRING
[PCS]
DPM
[AIS]
RGND
This document contains information for a new product. Crystal
Semiconductor reserves the right to modify this product without notice.
Copyright Crystal Semiconductor Corporation 1996
(All Rights Reserved)
MAY ’96
DS155PP2
1
CS61577
ABSOLUTE MAXIMUM RATINGS
Parameter
(referenced to RGND=TGND=0V)
Symbol
Min
Max
Units
DC Supply
RV+
6.0
V
TV+
(RV+) + 0.3
V
Input Voltage, Any Pin
(Note 1)
Vin
RGND-0.3
(RV+) + 0.3
V
Input Current, Any Pin
(Note 2)
Iin
-10
10
mA
Ambient Operating Temperature
TA
-40
85
°C
Storage Temperature
Tstg
-65
150
°C
WARNING:Operations at or beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
Notes: 1. Excluding RTIP, RRING, which must stay within -6V to (RV+) + 0.3V.
2. Transient currents of up to 100 mA will not cause SCR latch-up. Also TTIP, TRING, TV+ and TGND
can withstand a continuous current of 100 mA.
RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Min
Typ
Max
DC Supply
(Note 3) RV+, TV+
4.75
5.0
5.25
Ambient Operating Temperature
TA
-40
25
85
400
500
Power Consumption
(Notes 4,5)
PC
Power Consumption
(Notes 4,6)
PC
230
Notes: 3. TV+ must not exceed RV+ by more than 0.3V.
4. Power consumption while driving line load over operating temperature range. Includes IC and
Digital input levels are within 10% of the supply rails and digital outputs are driving a 50 pF
capacitive load.
5. Assumes 100% ones density and maximum line length at 5.25V.
6. Assumes 50% ones density and 300ft. line length at 5.0V.
DIGITAL CHARACTERISTICS
Parameter
load.
(TA = -40°C to 85°C; TV+, RV+ = 5.0V ±5%; GND = 0V)
Symbol
Min
Typ
Max
2.0
High-Level Input Voltage
(Notes 7, 8)
VIH
PINS 1-4, 17, 18, 23-28
Low-Level Input Voltage
(Notes 7, 8)
VIL
0.8
PINS 1-4, 17, 18, 23-28
High-Level Output Voltage
(Notes 7, 8, 9)
VOH
4.0
IOUT = -40 µA
PINS 6-8, 11, 12, 25
0.4
Low-Level Output Voltage
(Notes 7, 8, 9)
VOL
IOUT = 1.6 mA
PINS 6-8, 11, 12, 23, 25
Input Leakage Current (Except Pin 5)
±10
Low-Level Input Voltage, PIN 5
VIL
0.2
High-Level Input Voltage, PIN 5
VIH
(RV+) - 0.2
Mid-Level Input Voltage, PIN 5
(Note 10)
VIM
2.3
2.7
Notes: 7. In Extended Hardware Mode, pins 17 and 18 are digital inputs. In Host Mode, pin 23 is
an open drain output and pin 25 is a tristate output.
8. This specification guarantees TTL compatibility (VOH = 2.4V @ IOUT = -40µA).
9. Output drivers will drive CMOS logic levels into a CMOS load.
10. As an alternative to supplying a 2.3-to-2.7V input, this pin may be left floating.
2
Units
V
°C
mW
mW
Units
V
V
V
V
µA
V
V
V
DS155PP2
CS61577
ANALOG SPECIFICATIONS
Parameter
(TA = -40°C to 85°C; TV+, RV+ = 5.0V ±5%; GND = 0V)
Min
Typ
Max
Units
Transmitter
AMI Output Pulse Amplitudes
(Note 11)
2.14
2.37
2.6
V
E1, 75 Ω
(Note 12)
2.7
3.0
3.3
V
E1, 120 Ω
(Note 13)
2.7
3.0
3.3
V
T1, (FCC Part 68)
(Note 14)
2.4
3.0
3.6
V
T1, DSX-1
(Note 15)
Load Presented To Transmitter Output
(Note 11)
25
Ω
Jitter Added During Remote Loopback
(Note 16)
10Hz - 8kHz
0.005
UI
8kHz - 40kHz
0.008
UI
0.010
UI
10Hz - 40kHz
Broad Band
0.015
UI
Power in 2kHz band about 772kHz
(Notes 11, 17)
12.6
15
17.9
dBm
Power in 2kHz band about 1.544MHz
(Notes 11, 17)
-29
-38
dB
(referenced to power in 2kHz band at 772kHz)
Positive to Negative Pulse Imbalance
(Notes 11, 17)
0.2
0.5
dB
Transmitter Output Impedance
(Notes 17, 18)
10
Ω
Transmitter Short Circuit Current
(Notes 11, 19)
50
mA RMS
Notes: 11. Using a 0.47 µF capacitor in series with the primary of a transformer recommended
in the Applications Section.
12. Pulse amplitude measured at the output of the transformer across a 75 Ω load for line length
settings LEN2/1/0 = 0/0/1 and 0/0/0. For LEN2/1/0 = 0/0/0 only, a 4.4 Ω resistor is required
in series with the transformer primary.
13. Pulse amplitude measured at the output of the transformer across a 120 Ω load for line length
setting LEN2/1/0 = 0/0/0.
14. Pulse amplitude measured at the output of the transformer across a 100 Ω load for line length
setting LEN2/1/0 = 0/1/0.
15. Pulse amplitude measured at the DSX-1 Cross-Connect for all line length settings from
LEN2/1/0 = 0/1/1 to LEN2/1/0 = 1/1/1.
16. Input signal to RTIP/RRING is jitter free. Values will reduce slightly if jitter free clock is input to TCLK.
17. Not production tested. Parameters guaranteed by design and characterization.
18. Measured between the TTIP and TRING pins at 772 kHz during marks and spaces.
19. Measured broadband through a 0.5 Ω resistor across the secondary of the transmitter transformer
during the transmission of an all ones data pattern with LEN2/1/0 = 0/0/0 or 0/0/1.
DS155PP2
3
CS61577
ANALOG SPECIFICATIONS
(TA = -40°C to 85°C; TV+, RV+ = 5.0V ±5%; GND = 0V)
Parameter
Receiver
RTIP/RRING Input Impedance
Sensitivity Below DSX (0dB = 2.4V)
Loss of Signal Threshold
Data Decision Threshold
T1, DSX-1
(Note
T1, DSX-1
(Note
T1, (FCC Part 68) and E1 (Note
Allowable Consecutive Zeros before LOS
Receiver Input Jitter Tolerance
(Note
10kHz - 100kHz
2kHz
10Hz and below
Jitter Attenuator
20)
21)
22)
Min
Typ
Max
Units
-13.6
500
-
50k
0.30
-
Ω
dB
mV
V
60
53
45
160
65
65
50
175
70
77
55
190
% of peak
% of peak
% of peak
bits
0.4
6.0
300
-
-
UI
UI
UI
23)
Jitter Attenuation Curve Corner Frequency
(Notes 17, 24)
6
Hz
Attenuation at 10kHz Jitter Frequency
(Notes 17, 24)
50
dB
Attenuator Input Jitter Tolerance (Before Onset
12
23
UI
of FIFO Overflow or Underflow Protection)
(Notes 17, 24)
Notes: 20. For input amplitude of 1.2 Vpk to 4.14 Vpk.
21. For input amplitude of 0.5 Vpk to 1.2 Vpk and from 4.14 Vpk to RV+.
22. For input amplitude of 1.05 Vpk to 3.3 Vpk.
23. Jitter tolerance increases at lower frequencies. See Figure 11.
24. Attenuation measured with input jitter equal to 3/4 of measured jitter tolerance. Circuit attenuates
jitter at 20 dB/decade above the corner frequency. See Figure 12. Output jitter can increase
significantly when more than 12 UI’s are input to the attenuator. See discussion in the text section.
4
DS155PP2
CS61577
T1 SWITCHING CHARACTERISTICS
(TA = -40°C to 85°C; TV+, RV+ = 5.0V ±5%;
GND = 0V; Inputs: Logic 0 = 0V, Logic 1 = RV+; See Figures 1, 2, & 3)
Parameter
Symbol
Min
Typ
6.176000
Crystal Frequency
(Note 25)
fc
TCLK Frequency
ftclk
1.544
ACLKI Frequency
(Note 26)
faclki
1.544
RCLK Duty Cycle
(Note 27) tpwh1/tpw1
45
50
Rise Time, All Digital Outputs
(Note 28)
tr
Fall Time, All Digital Outputs
(Note 28)
tf
TPOS/TNEG (TDATA) to TCLK Falling Setup Time
tsu2
25
TCLK Falling to TPOS/TNEG (TDATA) Hold Time
th2
25
RPOS/RNEG Valid Before RCLK Falling
(Note 29)
tsu1
150
274
RDATA Valid Before RCLK Falling
(Note 30)
tsu1
150
274
RPOS/RNEG Valid Before RCLK Rising
(Note 31)
tsu1
150
274
RPOS/RNEG Valid After RCLK Falling
(Note 29)
th1
150
274
RDATA Valid After RCLK Falling
(Note 30)
th1
150
274
RPOS/RNEG Valid After RCLK Rising
(Note 31)
th1
150
274
Notes: 25. Crystal must meet specifications described in CXT6176/CXT8192 data sheet.
26. ACLKI provided by an external source or TCLK.
27. RCLK duty cycle will be 62.5% or 37.5% when jitter attenuator limits are reached.
28. At max load of 1.6 mA and 50 pF.
29. Host Mode (CLKE = 1).
30. Extended Hardware Mode.
31. Hardware Mode, or Host Mode (CLKE = 0)
32. The transmitted pulse width does not depend on the TCLK duty cycle.
E1 SWITCHING CHARACTERISTICS
Max
Units
55
85
85
-
MHz
MHz
MHz
%
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
(TA = -40°C to 85°C; TV+, RV+ = 5.0V ±5%;
GND = 0V; Inputs: Logic 0 = 0V, Logic 1 = RV+; See Figures 1, 2, & 3)
Parameter
Crystal Frequency
(Note
TCLK Frequency
TCLK Duty Cycle for LEN2/1/0 = 0/0/0
(Note
ACLKI Frequency
(Note
RCLK Duty Cycle
(Note
Rise Time, All Digital Outputs
(Note
Fall Time, All Digital Outputs
(Note
TPOS/TNEG (TDATA) to TCLK Falling Setup Time
TCLK Falling to TPOS/TNEG (TDATA) Hold Time
RPOS/RNEG Valid Before RCLK Falling
(Note
RDATA Valid Before RCLK Falling
(Note
RPOS/RNEG Valid Before RCLK Rising
(Note
RPOS/RNEG Valid After RCLK Falling
(Note
RDATA Valid After RCLK Falling
(Note
RPOS/RNEG Valid After RCLK Rising
(Note
DS155PP2
25)
32)
26)
27)
28)
28)
29)
30)
31)
29)
30)
31)
Symbol
fc
ftclk
tpwh2/tpw2
faclki
tpwh1/tpw1
tr
tf
tsu2
th2
tsu1
tsu1
tsu1
th1
th1
th1
Min
40
45
25
25
100
100
100
100
100
100
Typ
8.192000
2.048
50
2.048
50
194
194
194
194
194
194
Max
60
55
85
85
-
Units
MHz
MHz
%
MHz
%
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
5
CS61577
SWITCHING CHARACTERISTICS
(TA = -40° to 85°C; TV+, RV+ = ±5%;
Inputs: Logic 0 = 0V, Logic 1 = RV+)
Parameter
SDI to SCLK Setup Time
SCLK to SDI Hold Time
SCLK Low Time
SCLK High Time
SCLK Rise and Fall Time
CS to SCLK Setup Time
SCLK to CS Hold Time
CS Inactive Time
SCLK to SDO Valid
CS to SDO High Z
Input Valid To PCS Falling Setup Time
PCS Rising to Input Invalid Hold Time
PCS Active Low Time
Notes: 33. Output load capacitance = 50pF
(Note 33)
Symbol
Min
Typ
Max
Units
tdc
tcdh
tcl
tch
tr, tf
tcc
tcch
tcwh
tcdv
tcdz
tsu4
th4
tpcsl
50
50
240
240
50
50
250
50
50
250
100
-
50
200
-
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
tr
Any Digital Output
tf
90%
10%
90%
10%
Figure 1. Signal Rise and Fall Characteristics
tpw1
RCLK
t pwl1
RPOS
RNEG
RDATA
BPV
t su1
t pwh1
EXTENDED
HARDWARE
MODE OR
HOST MODE
(CLKE = 1)
t h1
HARDWARE
MODE OR
HOST MODE
(CLKE = 0)
RCLK
Figure 2. Recovered Clock and Data Switching Characteristics
6
DS155PP2
CS61577
t pw2
t pwh2
TCLK
t su2
t h2
TPOS/TNEG
Figure 3. Transmit Clock and Data Switching Characteristics
t cwh
CS
t cc
t cch
t ch
t cl
SCLK
t cdh
t dc
SDI
LSB
t cdh
LSB
CONTROL
BYTE
MSB
DATA
BYTE
Figure 4. Serial Port Write Timing Diagram
CS
t cdz
SCLK
t cdv
SDO
HIGH Z
CLKE = 1
Figure 5. Serial Port Read Timing Diagram
PCS
t su4
LEN0/1/2, TAOS,
RLOOP, LLOOP,
RCODE, TCODE
th4
t pcsl
VALID INPUT DATA
Figure 6. Extended Hardware Mode Parallel Chip Select Timing Diagram
DS155PP2
7
CS61577
THEORY OF OPERATION
CS61577 Enhancements Relative to CS61574
Existing designs using the CS61574 can be converted to the higher performance, pin-compatible
CS61577 with no changes to the PCB, external
component or system software.
The CS61577 provides higher performance and
more features than the CS61574 including:
•
•
•
•
•
•
•
•
•
•
Selection of 75 Ω or 120 Ω E1 output options under software or hardware control,
50 mARMS transmitter short-circuit current
limiting for E1 (per OFTEL OTR-001),
internally controlled pulse width for E1
output options,
35% lower power consumption,
Increased transmitter immunity to signal reflections for improved signal quality,
Optional AMI, B8ZS, HDB3 encoder/decoder or external line coding support,
Receiver AIS (unframed all ones) detection,
Improved receiver Loss of Signal handling
(LOS set at power-up, reset upon receipt of
3 ones in 32 bit periods with no more than
15 consecutive zeros),
Transmitter TTIP and TRING outputs are
forced low when TCLK is static,
The Driver Performance Monitor operates
over a wider range of input signal levels.
Introduction to Operating Modes
The CS61577 supports three operating modes
which are selected by the level of the MODE pin
as shown in Tables 1 and 2, Figure 7, and Figures
A1-A3 of the Applications section.
The modes are Hardware Mode, Extended Hardware Mode, and Host Mode. In Hardware and
Extended Hardware Modes, discrete pins are used
to configure and monitor the device. The Extended Hardware Mode provides a parallel chip
select input which latches the control inputs al8
lowing individual ICs to be configured using a
common set of control lines. In the Host Mode,
an external processor monitors and configures the
device through a serial interface. There are thirteen multi-function pins whose functionality is
determined by the operating mode. (see Table 2).
Hardware
Mode
Control
Method
Control
Pins
MODE
Pin
Level
Line
Coding
<0.2 V
AIS
Detection
Driver
Performance
Monitor
External
Extended
Host
Hardware
Mode
Mode
Control Pins
Serial
with Parallel
Interface
Chip Select
Floating or >(RV+)-0.2 V
2.5 V
External
No
InternalAMI, B8ZS,
or HDB3
Yes
Yes
No
Yes
No
Table 1. Differences Between Operating Modes
MODE
EXTENDED
FUNCTION
PIN HARDWARE HARDWARE
3
TPOS
TDATA
TRANSMITTER
4
TNEG
TCODE
6
RNEG
BPV
7
RPOS
RDATA
RECEIVER/DPM
11
DPM
AIS
RCODE
17
MTIP
18
MRING
18
PCS
23
LEN0
LEN0
24
LEN1
LEN1
CONTROL
25
LEN2
LEN2
26
RLOOP
RLOOP
27
LLOOP
LLOOP
28
TAOS
TAOS
HOST
TPOS
TNEG
RNEG
RPOS
DPM
MTIP
MRING
INT
SDI
SDO
CS
SCLK
CLKE
Table 2. Pin Definitions
DS155PP2
CS61577
HARDWARE MODE
TAOS
LLOOP
RLOOP
LEN0/1/2
CONTROL
TPOS
TTIP
LINE DRIVER
TNEG
CS62180B
FRAMER
CIRCUIT
CS61577
TRING
MRING
MTIP
DRIVER MONITOR
DPM
RTIP
RPOS
RNEG
JITTER
ATTENUATOR
TRANSMIT
TRANSFORMER
LINE RECEIVER
RRING
RECEIVE
TRANSFORMER
EXTENDED HARDWARE MODE
TCODE
RCODE
TAOS LLOOP
RLOOP
PCS
LEN0/1/2
CONTROL
TTIP
TDATA
LINE DRIVER
AMI
B8ZS,
HDB3,
CODER
T1 or E1
REPEATER
OR
MUX
BPV
RTIP
JITTER
ATTENUATOR
LINE
RECEIVER
RRING
RECEIVE
TRANSFORMER
AIS
HOST MODE
µP SERIAL PORT
5
CONTROL
TRANSMIT
TRANSFORMER
CS61577
AIS
DETECT
RDATA
TRING
CLKE
CONTROL
TTIP
TPOS
LINE DRIVER
TNEG
CS62180B
FRAMER
CIRCUIT
CS61577
DRIVER MONITOR
TRING
MRING
MTIP
DPM
RTIP
RPOS
RNEG
JITTER
ATTENUATOR
TRANSMIT
TRANSFORMER
LINE RECEIVER
RRING
RECEIVE
TRANSFORMER
Figure 7. Overview of Operating Modes
DS155PP2
9
CS61577
NORMALIZED
AMPLITUDE
Transmitter
The transmitter takes digital T1 or E1 input data
and drives appropriately shaped bipolar pulses
onto a transmission line through a 1:2 transformer. The transmit data (TPOS & TNEG or
TDATA) is supplied synchronously and sampled
on the falling edge of the input clock, TCLK.
ANSI T1.102,
AT&T CB 119
SPECIFICATIONS
1.0
0.5
0
Either T1 (DSX-1 or Network Interface) or E1
CCITT G.703 pulse shapes may be selected.
Pulse shaping and signal level are controlled by
"line length select" inputs as shown in Table 3.
OUTPUT
PULSE SHAPE
-0.5
0
250
500
750
1000
TIME (nanoseconds)
For T1 DSX-1 applications, line lengths from 0 to
655 feet (as measured from the transmitter to the
DSX-1 cross connect) may be selected. The five
partition arrangement in Table 3 meets ANSI
T1.102 and AT&T CB-119 requirements when
using #22 ABAM cable. A typical output pulse is
shown in Figure 8. These pulse settings can also
be used to meet CCITT pulse shape requirements
for 1.544 MHz operation.
For T1 Network Interface applications, two additional options are provided. Note that the optimal
pulse width for Part 68 (324 ns) is narrower than
the optimal pulse width for DSX-1 (350 ns). The
CS61577 automatically adjusts the pulse width
based upon the "line length" selection made.
LEN2 LEN1 LEN0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
0
0
0
0
0
1
0
0
1
1
0
1
Option Selected
0-133 FEET
133-266 FEET
266-399 FEET
399-533 FEET
533-655 FEET
75 Ω (with 4.4 Ω
resistor) & 120 Ω
75 Ω (without
4.4 Ω resistor)
FCC PART 68, OPT. A
ANSI T1.403
Application
DSX-1
ABAM
(AT&T 600B
or 600C)
E1
CCITT G.703
Figure 8. Typical Pulse Shape at DSX-1 Cross Connect
The E1 G.703 pulse shape is supported with line
length selections LEN2/1/0=0/0/0 or
LEN2/1/0=0/0/1. As with the CS61574,
LEN2/1/0=0/0/0 supports the 120 Ω, 3 V output
option without external series resistors, but will
also support the 75 Ω, 2.37 V output option with
an external 4.4 Ω resistor in series with TTIP or
TRING. The new LEN2/1/0=0/0/1 code supports
the 75 Ω, 2.37 V output option without external
series resistors allowing for software selection between the two E1 output options. The pulse width
will meet the G.703 pulse shape template shown
in Figure 9, and specified in Table 4.
The CS61577 will detect a static TCLK, and will
force TTIP and TRING low to prevent transmission when data is not present. When any transmit
control pin (TAOS, LEN0-2 or LLOOP) is toggled, the transmitter outputs will require
approximately 22 bit periods to stabilize. The
transmitter will take longer to stabilize when
RLOOP is selected because the timing circuitry
must adjust to the new frequency.
NETWORK
INTERFACE
Table 3. Line Length Selection
10
DS155PP2
CS61577
Percent of
nominal
peak
voltage
Receiver
269 ns
120
110
244 ns
100
194 ns
90
80
50
10
Nominal Pulse
0
-10
-20
219 ns
The receiver extracts data and clock from an AMI
(Alternate Mark Inversion) coded signal and outputs clock and synchronized data. The receiver is
sensitive to signals over the entire range of
ABAM cable lengths and requires no equalization
or ALBO (Automatic Line Build Out) circuits.
The signal is received on both ends of a centertapped, center-grounded transformer. The
transformer is center tapped on the IC side. The
clock and data recovery circuit exceeds the jitter
tolerance specifications of Publications 43802,
43801, AT&T 62411, TR-TSY-000170, and
CCITT REC. G.823.
488 ns
Figure 9. Mask of the Pulse at the 2048 kbps Interface
Transmit All Ones Select
The transmitter provides for all ones insertion at
the frequency of TCLK. Transmit all ones is selected when TAOS goes high, and causes
continuous ones to be transmitted on the line
(TTIP and TRING). In this mode, the TPOS and
TNEG (or TDATA) inputs are ignored. If Remote
Loopback is in effect, any TAOS request will be
ignored.
A block diagram of the receiver is shown in Figure 10. The two leads of the transformer (RTIP
and RRING) have opposite polarity allowing the
receiver to treat RTIP and RRING as unipolar signals. Comparators are used to detect pulses on
RTIP and RRING. The comparator thresholds are
dynamically established at a percent of the peak
level (50% of peak for E1, 65% of peak for T1;
with the slicing level selected by LEN2/1/0 inputs).
The leading edge of an incoming data pulse triggers the clock phase selector. The phase selector
chooses one of the 13 available phases which the
delay line produces for each bit period. The outFor c oax ia l c able, For shielded twisted
75Ω
loa d
a nd pair, 120Ω load and
transformer specified transformer specified
in Application Section. in Application Section.
2.37 V
3V
0 ±0.237 V
0 ±0.30 V
244 ns
Nominal peak voltage of a mark (pulse)
Peak voltage of a space (no pulse)
Nominal pulse width
Ratio of the amplitudes of positive and negative
0.95 to 1.05*
pulses at the center of the pulse interval
Ratio of the widths of positive and negative
0.95 to 1.05*
pulses at the nominal half amplitude
* When configured with a 0.47 µF nonpolarized capacitor in series with the TX transformer
primary as shown in Figures A1, A2 and A3.
Table 4. CCITT G.703 Specifications
DS155PP2
11
CS61577
RTIP
1:2
Data
Level
Slicer
Data
Sampling
& Clock
Extraction
Edge
Detector
Clock
Phase
Selector
RRING
RPOS
Jitter
Attenuator
RNEG
RCLK
Continuously
Calibrated
Delay Line
Figure 10. Receiver Block Diagram
put from the phase selector feeds the clock and
data recovery circuits which generate the recovered clock and sample the incoming signal at
appropriate intervals to recover the data.
Data sampling will continue at the periods selected by the phase selector until an incoming
pulse deviates enough to cause a new phase to be
selected for data sampling. The phases of the delay line are selected and updated to allow as much
as 0.4 UI of jitter from 10 kHz to 100 kHz, without error. The jitter tolerance of the receiver
exceeds that shown in Figure 11. Additionally,
this method of clock and data recovery is tolerant
of long strings of consecutive zeros. The data
Minimum
Performance
300
138
100
AT&T 62411
PEAK-TO-PEAK
JITTER
(unit intervals)
28
sampler will continuously sample data based on
its last input until a new pulse arrives to update
the clock phase selector.
The delay line is continuously calibrated using
the crystal oscillator reference clock. The delay
line produces 13 phases for each cycle of the reference clock. In effect, the 13 phases are
analogous to a 20 MHz clock when the reference
clock is 1.544 MHz. This implementation utilizes
the benefits of a 20 MHz clock for clock recovery
without actually having the clock present to impede analog circuit performance.
In the Hardware Mode, data at RPOS and RNEG
should be sampled on the rising edge of RCLK,
the recovered clock. In the Extended Hardware
Mode, data at RDATA should be sampled on the
falling edge of RCLK. In the Host Mode, CLKE
determines the clock polarity for which output
data should be sampled as shown in Table 5.
10
1
.4
.1
1
10
100 300 700 1k
10k
100k
JITTER FREQUENCY (Hz)
Figure 11. Minimum Input Jitter Tolerance of Receiver
(Clock Recovery Circuit and Jitter Attenuator)
12
DS155PP2
CS61577
MODE
(pin 5)
CLKE
(pin 28)
DATA
CLOCK
Clock Edge for
Valid Data
LOW
(<0.2V)
X
RPOS
RNEG
RCLK
RCLK
Rising
Rising
HIGH
(>(V+) - 0.2V)
LOW
RPOS
RNEG
SDO
RCLK
RCLK
SCLK
Rising
Rising
Falling
HIGH
(>(V+) - 0.2V)
HIGH
RPOS
RNEG
SDO
RCLK
RCLK
SCLK
Falling
Falling
Rising
MIDDLE
(2.5V)
X
RDATA
RCLK
Falling
X = Don’t Care
This means that RCLK will smoothly transition
to the new frequency. If ACLKI is not present,
then the crystal oscillator of the jitter attenuator is
forced to its center frequency. Table 6 shows the
status of RCLK upon LOS.
Crystal
present?
No
Yes
ACLKI
present?
Yes
No
Yes
Yes
Source of RCLK
ACLKI
Centered Crystal
ACLKI via the
Jitter Attenuator
Table 5. Data Output/Clock Relationship
Loss of Signal
The receiver will indicate loss of signal after
power-up, reset or upon receiving 175 consecutive zeros. A digital counter counts received
zeros, based on RCLK cycles. A zero is received
when the RTIP and RRING inputs are below the
input comparator slicing threshold level established by the peak detector. After the signal is
removed for a period of time the data slicing
threshold level decays to approximately
300 mVpeak.
The receiver reports loss of signal by setting the
Loss of Signal pin, LOS, high. If the serial interface is used, the LOS bit will be set and an
interrupt will be issued on INT (unless disabled).
LOS will return low (asserting the INT pin again
in Host Mode) upon receipt of 3 ones in 32 bit
periods with no more than 15 consecutive zeros.
Note that in the Host Mode, LOS is simultaneously available from both the register and pin 12.
RPOS/RNEG or RDATA are forced low during
LOS unless the jitter attenuator is disabled. (See
"Jitter Attenuator" section)
If ACLKI is present during the LOS state, ACLKI
is switched into the input of the jitter attenuator,
resulting in RCLK matching the frequency of
ACLKI. The jitter attenuator buffers any instantaneous changes in phase between the last
recovered clock and the ACLKI reference clock.
DS155PP2
Table 6. RCLK Status at LOS
Jitter Attenuator
The jitter attenuator reduces wander and jitter in
the recovered clock signal. It consists of a 32-bit
FIFO, a crystal oscillator, a set of load capacitors
for the crystal, and control logic. The jitter attenuator exceeds the jitter attenuation requirements of
Publications 43802 and REC. G.742.
The jitter attenuator works in the following manner. The recovered clock and data are input to the
FIFO with the recovered clock controlling the
FIFO’s write pointer. The crystal oscillator controls the FIFO’s read pointer which reads data out
of the FIFO and presents it at RPOS and RNEG
(or RDATA). The update rate of the read pointer
is analogous to RCLK. By changing the load capacitance that the IC presents to the crystal, the
oscillation frequency is adjusted to the average
frequency of the recovered signal. Logic determines the phase relationship between the read and
write pointers and decides how to adjust the load
capacitance of the crystal. Thus the jitter attenuator behaves as a first-order phase lock loop. Jitter
is absorbed in the FIFO according to the jitter
transfer characteristic shown in Figure 12.
13
CS61577
Local Loopback
0
a) Minimum Attenuation Limit
Attenuation in dB
10
62411 Requirements
20
Local loopback is selected by taking LLOOP, pin
27, high or by setting the LLOOP register bit via
the serial interface.
30
b) Maximum
Attenuation
Limit
40
50
Measured Performance
60
1
10
100
1k
Frequency in Hz
10 k
Figure 12. Typical Jitter Transfer Function
The FIFO in the jitter attenuator is designed to
prevent overflow and underflow. If the jitter amplitude becomes very large, the read and write
pointers may get very close together. Should they
attempt to cross, the oscillator’s divide by four
circuit adjusts by performing a divide by 3 1/2 or
divide by 4 1/2 to prevent the overflow or underflow. During this activity, data will never be lost.
The local loopback mode takes clock and data
presented on TCLK, TPOS, and TNEG (or
TDATA), sends it through the jitter attenuator and
outputs it at RCLK, RPOS and RNEG (or
RDATA). If the jitter attenuator is disabled, it is
bypassed. Inputs to the transmitter are still transmitted on TTIP and TRING, unless TAOS has
been selected in which case, AMI-coded continuous ones are transmitted at the TCLK frequency.
The receiver RTIP and RRING inputs are ignored
when local loopback is in effect.
Remote Loopback
Remote loopback is selected by taking RLOOP,
pin 26, high or by setting the RLOOP register bit
via the serial interface.
The 32-bit FIFO in the CS61577 attenuator allows it to absorb jitter with minimum data delay
in T1 and E1 switching or transmission applications. Like the CS61574, the CS61577 will
tolerate large amplitude jitter (>23 UIpp) by
tracking rather than attenuating it, preventing data
errors so that the jitter may be absorbed in external frame buffers.
In remote loopback, the recovered clock and data
input on RTIP and RRING are sent through the
jitter attenuator and back out on the line via TTIP
and TRING. Selecting remote loopback overrides
any TAOS request (see Table 6). The recovered
incoming signals are also sent to RCLK, RPOS
and RNEG (or RDATA). A remote loopback occurs in response to RLOOP going high.
The jitter attenuator may be bypassed by pulling
XTALIN to RV+ through a 1 kΩ resistor and providing a 1.544 MHz (or 2.048 MHz) clock on
ACLKI. RCLK may exhibit quantization jitter of
approximately 1/13 UIpp and a duty cycle of approximately 30% (70%) when the attenuator is
disabled.
RLOOP TAOS
Input
Input
Signal Signal
Source of
Data for
TTIP & TRING
Source of
Clock for
TTIP & TRING
0
0
TDATA
TCLK
0
1
all 1s
TCLK
1
X
RTIP & RRING
RTIP & RRING (RCLK)
Notes: 1. X = Don’t Care. The identified All Ones Select
input is ignored when the indicated loopback is
in effect.
2. Logic 1 indicates that Loopback or All Ones
option is selected.
Table 7. Interaction of RLOOP with TAOS
14
DS155PP2
CS61577
Simultaneous selection of local and remote loopback modes is not valid (see Reset).
In the Extended Hardware Mode the transmitted
data is looped before the AMI/B8ZS/HDB3 encoder/decoder during remote loopback so that the
transmitted signal matches the received signal,
even in the presence of received bipolar violations. Data output on RDATA is decoded,
however, if RCODE is low.
Alarm Indication Signal
In the Extended Hardware Mode, the receiver sets
the output pin AIS high when less than 3 zeros
are detected out of 2048 bit periods.
Line Code Encoder/Decoder
In the Extended Hardware Mode, three line codes
are available: AMI, B8ZS and HDB3. The input
to the encoder is TDATA. The outputs from the
decoder are RDATA and BPV (Bipolar Violation
Strobe). The encoder and decoder are selected
using the LEN2, LEN1, LEN0, TCODE and
RCODE pins as shown in Table 8.
TCODE
(Transmit
Encoder
Selection)
RCODE
(Receiver
Decoder
Selection)
LOW
HIGH
LOW
HIGH
LEN 2/1/0
000
010-111
HDB3
B8ZS
Encoder
Encoder
AMI Encoder
HDB3
Decoder
B8ZS
Decoder
AMI Decoder
Table 8. Encoder/Decoder Selection
DS155PP2
Parallel Chip Select
In the Extended Hardware Mode, PCS can be
used to gate the digital control inputs: TCODE,
RCODE, LEN0, LEN1, LEN2, RLOOP, LLOOP
and TAOS. Inputs are accepted on these pins only
when PCS is low and will immediately change
the operating state of the device. Therefore, when
cycling PCS to update the operating state, the
digital control inputs should be stable for the entire PCS low period. The digital control inputs are
ignored when PCS is high
Driver Performance Monitor
To aid in early detection and easy isolation of
non-functioning links, the IC is able to monitor
transmit drive performance and report when the
driver is no longer operational. This feature can
be used to monitor either the device’s performance or the performance of a neighboring driver.
The driver performance monitor indicator is normally low, and goes high upon detecting a driver
failure.
The driver performance monitor consists of an activity detector that monitors the transmitted signal
when MTIP is connected to TTIP and MRING is
connected to TRING. DPM will go high if the
absolute difference between MTIP and MRING
does not transition above or below a threshold
level within a time-out period. In the Host Mode,
DPM is available from the register and pin 11.
Whenever more than one line interface IC resides
on the same circuit board, the effectiveness of the
driver performance monitor can be maximized by
having each IC monitor performance of a neighboring IC, rather than having it monitor its own
performance. Note that a CS61577 can not be
used to monitor a CS61574 due to output stage
differences.
15
CS61577
CS
SCLK
SDI
R/W
0
0
0
0
1
0
0
D0
D1
D2
D3
D4
D5
Data Input/Output
D6
D0
D1
D2
D6
Address/Command Byte
SDO
D3
D4
D5
D7
D7
Figure 13. Input/Output Timing
Serial Interface
In the Host Mode, pins 23 through 28 serve as a
microprocessor/microcontroller interface. One
on-board register can be written to via the SDI
pin or read from via the SDO pin at the clock rate
determined by SCLK. Through this register, a
host controller can be used to control operational
characteristics and monitor device status. The serial port read/write timing is independent of the
system transmit and receive timing.
Data transfers are initiated by taking the chip select input, CS, low (CS must initially be high).
Address and input data bits are clocked in on the
rising edge of SCLK. The clock edge on which
output data is stable and valid is determined by
CLKE as shown in Table 5. Data transfers are terminated by setting CS high. CS may go high no
sooner than 50 ns after the rising edge of the
SCLK cycle corresponding to the last write bit.
For a serial data read, CS may go high any time
to terminate the output.
Figure 13 shows the timing relationships for data
transfers when CLKE = 1. When CLKE = 1, data
bit D7 is held until the falling edge of the 16th
clock cycle. When CLKE = 0, data bit D7 is held
until the rising edge of the 17th clock cycle. SDO
goes High-Z after CS goes high or at the end of
the hold period of data bit D7.
LSB, first bit
0
1
2
3
4
5
6
R/W
ADD0
ADD1
ADD2
ADD3
ADD4
-
Read/Write Select; 0 = write, 1 = read
LSB of address, Must be 0
Must be 0
Must be 0
Must be 0
Must be 1
Reserved - Must be 0
Table 9. Address/Command Byte
An address/command byte, shown in Table 9, precedes a data register. The first bit of the
address/command byte determines whether a read
or a write is requested. The next six bits contain
the address. The line interface responds to address
16 (0010000). The last bit is ignored.
The data register, shown in Table 10, can be written to the serial port. Data is input on the eight
clock cycles immediately following the address/command byte. Bits 0 and 1 are used to
clear an interrupt issued from the INT pin, which
occurs in response to a loss of signal or a problem
with the output driver.
LSB: first bit in
0
1
2
3
4
5
6
MSB: last bit in 7
clr LOS
clr DPM
LEN0
LEN1
LEN2
RLOOP
LLOOP
TAOS
Clear Loss of Signal
Clear Driver Performance Monitor
Bit 0 - Line Length Select
Bit 1 - Line Length Select
Bit 2 - Line Lenght Select
Remote Loopback
Local Loopback
Transmit All Ones Select
NOTE: Setting 5, 6, & 7 to 101 or 111 puts the CS61577 into a
factory test mode.
Table 10. Input Data Register
16
DS155PP2
CS61577
Writing a "1" to either "Clear LOS" or "Clear
DPM" over the serial interface has three effects:
1) The current interrupt on the serial interface
will be cleared. (Note that simply reading
the register bits will not clear the interrupt).
2) Output data bits 5, 6 and 7 will be reset as
appropriate.
3) Future interrupts for the corresponding LOS
or DPM will be prevented from occurring.
Writing a "0" to either "Clear LOS" or "Clear
DPM" enables the corresponding interrupt for
LOS or DPM.
Input bits 5/6/7=111 and 5/6/7=101 are the same
request, and cause the line interface to enter into
the factory test mode. In other words, when
RLOOP=1 (Bit 5) and TAOS=1 (Bit 7), LOOP
(Bit 6) is a don’t care. For normal operation,
RLOOP and TAOS should not be simultaneously
selected via the serial interface.
Output data from the serial interface is presented
as shown in Tables 11 and 12. Bits 2, 3 and 4 can
be read to verify line length selection. Bits 5, 6
and 7 must be decoded. Codes 101, 110 and 111
(Bits 5, 6 and 7) indicate intermittent losses of
signal and/or driver problems.
SDO goes to a high impedance state when not in
use. SDO and SDI may be tied together in applications where the host processor has a
bi-directional I/O port.
LSB: first bit in
0
1
2
3
4
LOS
DPM
LEN0
LEN1
LEN2
Loss of Signal
Driver Performance Monitor
Bit 0 - Line Length Select
Bit 1 - Line Length Select
Bit 2 - Line Lenght Select
Table 11. Output Data Bits 0 - 4
DS155PP2
5
0
0
0
0
1
1
Bits
6
0
0
1
1
0
0
7
0
1
0
1
0
1
Status
Reset has occurred or no program input.
TAOS in effect.
LLOOP in effect.
TAOS/LLOOP in effect.
RLOOP in effect
DPM changed state since last "clear DPM"
occured.
1 1 0 LOS changed state since last "clear LOS"
occured.
1 1 1 LOS and DPM have changed state since
last "clear LOS" and "clear DPM".
Table 12. Coding for Serial Output bits 5,6,7
Power On Reset / Reset
Upon power-up, the IC is held in a static state
until the supply crosses a threshold of approximately 3 Volts. When this threshold is crossed,
the device will delay for about 10 ms to allow the
power supply to reach operating voltage. After
this delay, calibration of the delay lines used in
the transmit and receive sections commences. The
delay lines can be calibrated only if a reference
clock is present. The reference clock for the receiver is provided by the crystal oscillator, or
ACLKI if the oscillator is disabled. The reference
clock for the transmitter is provided by TCLK.
The initial calibration should take less than
20 ms.
In operation, the delay lines are continuously calibrated, making the performance of the device
independent of power supply or temperature variations. The continuous calibration function
forgoes any requirement to reset the line interface
when in operation. However, a reset function is
available which will clear all registers.
In the Hardware and Extended Hardware Modes,
a reset request is made by simultaneously setting
both the RLOOP and LLOOP pins high for at
least 200 ns. Reset will initiate on the falling edge
of the reset request (falling edge of RLOOP and
LLOOP). In the Host Mode, a reset is initiated by
simultaneously writing RLOOP and LLOOP to
17
CS61577
the register. In either mode, a reset will set all registers to 0 and force the oscillator to its center
frequency before initiating calibration. A reset
will also set LOS high.
Power Supply
The device operates from a single +5 Volt supply.
Separate pins for transmit and receive supplies
provide internal isolation. These pins should be
connected externally near the device and decoupled to their respective grounds. TV+ must not
exceed RV+ by more than 0.3V.
Schematic & Layout Review Service
Confirm Optimum
Schematic & Layout
Before Building Your Board.
For Our Free Review Service
Call Applications Engineering.
C a l l : ( 5 1 2 ) 4 4 5 - 7 2 2 2
Decoupling and filtering of the power supplies is
crucial for the proper operation of the analog circuits in both the transmit and receive paths. A 1.0
µF capacitor should be connected between TV+
and TGND, and a 0.1 µF capacitor should be connected between RV+ and RGND. Use mylar or
ceramic capacitors and place them as closely as
possible to their respective power supply pins. A
68 µF tantalum capacitor should be added close
to the RV+/RGND supply. Wire-wrap breadboarding of the line interface is not recommended
because lead resistance and inductance serve to
defeat the function of the decoupling capacitors.
18
DS155PP2
CS61577
PIN DESCRIPTIONS
Hardware Mode
ACLKI
TCLK
TPOS
TNEG
MODE
RNEG
RPOS
RCLK
XTALIN
XTALOUT
DPM
LOS
TTIP
TGND
1
28
2
27
3
26
4
25
5
24
6
23
7
22
8
21
9
20
10
19
11
18
12
17
13
16
14
15
TAOS
LLOOP
RLOOP
LEN2
LEN1
LEN0
RGND
RV+
RRING
RTIP
MRING
MTIP
TRING
TV+
Extended Hardware Mode
ACLKI
TCLK
TAOS
TPOS
LLOOP
TNEG
RLOOP
MODE
LEN2
RNEG
RPOS
RCLK
XTALIN
XTALOUT
5
4
3
2
1
28 27 26 25
6
24
7
23
8
top
view
22
9
21
10
20
19
11
LEN1
LEN0
RGND
RV+
RRING
12 13 14 15 16 17 18
DPM
RTIP
LOS
MRING
TTIP
MTIP
TGND
TRING
TV+
DS155PP2
19
CS61577
Host Mode
ACLKI
TCLK
TPOS
TNEG
MODE
RNEG
RPOS
RCLK
XTALIN
XTALOUT
DPM
LOS
TTIP
TGND
1
28
2
27
3
26
4
25
5
24
6
23
7
22
8
21
9
20
10
19
11
18
12
17
13
16
14
15
CLKE
SCLK
CS
SDO
SDI
INT
RGND
RV+
RRING
RTIP
MRING
MTIP
TRING
TV+
ACLKI
TCLK
CLKE
TPOS
SCLK
TNEG
CS
MODE
SDO
RNEG
RPOS
RCLK
XTALIN
XTALOUT
5
4
3
2
1
28 27 26 25
6
24
7
23
8
top
view
22
9
21
10
20
19
11
SDI
INT
RGND
RV+
RRING
12 13 14 15 16 17 18
DPM
RTIP
LOS
MRING
TTIP
MTIP
TGND
TRING
TV+
20
DS155PP2
CS61577
Power Supplies
RGND - Ground, Pin 22.
Power supply ground for all subcircuits except the transmit driver; typically 0 Volts.
RV+ - Power Supply, Pin 21.
Power supply for all subcircuits except the transmit driver; typically +5 Volts.
TGND - Ground, Transmit Driver, Pin 14.
Power supply ground for the transmit driver; typically 0 Volts.
TV+ - Power Supply, Transmit Driver, Pin 15.
Power supply for the transmit driver; typically +5 Volts. TV+ must not exceed RV+ by more than
0.3 V.
Oscillator
XTALIN, XTALOUT - Crystal Connections, Pins 9 and 10.
A 6.176 MHz (or 8.192 MHz) crystal should be connected across these pins. If a 1.544 MHz (or
2.048 MHz) clock is provided on ACLKI (pin 1), the jitter attenuator may be disabled by tying
XTALIN, Pin 9 to RV+ through a 1 kΩ resistor, and floating XTALOUT, Pin 10.
Overdriving the oscillator with an external clock is not supported.
Control
ACLKI - Alternate External Clock Input, Pin 1.
A 1.544 MHz (or 2.048 MHz) clock may be input to ACLKI, or this pin must be tied to ground.
During LOS, the ACLKI input signal, if present, is output on RCLK through the jitter attenuator.
CLKE - Clock Edge, Pin 28. (Host Mode)
Setting CLKE to logic 1 causes RPOS and RNEG to be valid on the falling edge of RCLK, and
SDO to be valid on the rising edge of SCLK. Conversely, setting CLKE to logic 0 causes RPOS
and RNEG to be valid on the rising edge of RCLK, and SDO to be valid on the falling edge of
SCLK.
CS - Chip Select, Pin 26. (Host Mode)
This pin must transition from high to low to read or write the serial port.
INT - Receive Alarm Interrupt, Pin 23. (Host Mode)
Goes low when LOS or DPM change state to flag the host processor. INT is cleared by writing
"clear LOS" or "clear DPM" to the register. INT is an open drain output and should be tied to the
power supply through a resistor.
DS155PP2
21
CS61577
LEN0, LEN1, LEN2 - Line Length Selection, Pins 23, 24 and 25. (Hardware and Extended
Hardware Modes)
Determines the shape and amplitude of the transmitted pulse to accommodate several cable types
and lengths. See Table 3 for information on line length selection. Also controls the receiver
slicing level and the line code in Extended Hardware Mode.
LLOOP - Local Loopback, Pin 27. (Hardware and Extended Hardware Modes)
Setting LLOOP to a logic 1 routes the transmit clock and data through the jitter attenuator to the
receive clock and data pins. TCLK and TPOS/TNEG (or TDATA) are still transmitted unless
overridden by a TAOS request. Inputs on RTIP and RRING are ignored.
MODE - Mode Select, Pin 5.
Driving the MODE pin high puts the line interface in the Host Mode. In the host mode, a serial
control port is used to control the line interface and determine its status. Grounding the MODE
pin puts the line interface in the Hardware Mode, where configuration and status are controlled
by discrete pins. Floating the MODE pin or driving it to +2.5 Vselects the Extended Hardware
Mode, where configuration and status are controlled by discrete pins. When floating MODE,
there should be no external load on the pin. MODE defines the status of 13 pins (see Table 2).
PCS - Parallel Chip Select, Pin 18. (Extended Hardware Mode)
Setting PCS high causes the line interface to ignore the TCODE, RCODE, LEN0, LEN1, LEN2,
RLOOP, LLOOP and TAOS inputs.
RCODE - Receiver Decoder Select, Pin 17. (Extended Hardware Mode)
Setting RCODE low enables B8ZS or HDB3 zero substitution in the receiver decoder. Setting
RCODE high enables the AMI receiver decoder (see Table 8).
RLOOP - Remote Loopback, Pin 26. (Hardware and Extended Hardware Modes)
Setting RLOOP to a logic 1 causes the recovered clock and data to be sent through the jitter
attenuator (if active) and through the driver back to the line. The recovered signal is also sent to
RCLK and RPOS/RNEG (or RDATA). Any TAOS request is ignored. In the Host Mode,
simultaneous selection of RLOOP & TAOS enables a factory test mode.
Simultaneously taking RLOOP and LLOOP high for at least 200 ns initiates a device reset.
SCLK - Serial Clock, Pin 27. (Host Mode)
Clock used to read or write the serial port registers. SCLK can be either high or low when the line
interface is selected using the CS pin.
SDI - Serial Data Input, Pin 24. (Host Mode)
Data for the on-chip register. Sampled on the rising edge of SCLK.
SDO - Serial Data Output, Pin 25. (Host Mode)
Status and control information from the on-chip register. If CLKE is high SDO is valid on the
rising edge of SCLK. If CLKE is low SDO is valid on the falling edge of SCLK. This pin goes to
a high-impedance state when the serial port is being written to or after bit D7 is output.
22
DS155PP2
CS61577
TAOS - Transmit All Ones Select, Pin 28. (Hardware and Extended Hardware Modes)
Setting TAOS to a logic 1 causes continuous ones to be transmitted at the frequency determined
by TCLK. In the Host Mode, simultaneous selection of RLOOP & TAOS enables a factory test
mode.
TCODE - Transmitter Encoder Select, Pin 4. (Extended Hardware Mode)
Setting TCODE low enables B8ZS or HDB3 zero substitution in the transmitter encoder. Setting
TCODE high enables the AMI transmitter encoder .
Data
RDATA - Receive Data - Pin 7. (Extended Hardware Mode)
Data recovered from the RTIP and RRING inputs is output at this pin, after being decoded by the
line code decoder. RDATA is NRZ. RDATA is stable and valid on the falling edge of RCLK.
RCLK - Recovered Clock, Pin 8.
The receiver recovered clock generated by the jitter attenuator is output on this pin.When in the
loss of signal state ACLKI (if present) is output on RCLK via the jitter attenuator. If ACLKI is
not present during LOS, RCLK is forced to the center frequency of the crystal oscillator..
RPOS, RNEG - Receive Positive Data, Receive Negative Data, Pins 6 and 7. (Hardware and Host
Modes)
The receiver recovered NRZ digital data is output on these pins. In the Hardware Mode, RPOS
and RNEG are stable and valid on the rising edge of RCLK. In the Host Mode, CLKE determines
the clock edge for which RPOS and RNEG are stable and valid. See Table 5. A positive pulse
(with respect to ground) received on the RTIP pin generates a logic 1 on RPOS, and a positive
pulse received on the RRING pin generates a logic 1 on RNEG.
RTIP, RRING - Receive Tip, Receive Ring, Pins 19 and 20.
The AMI receive signal is input to these pins. A center-tapped, center-grounded, 2:1, step-up
transformer is required on these inputs, as shown in Figure A1 in the Applications section. Data
and clock are recovered and output on RCLK and RPOS/RNEG or RDTA.
TCLK - Transmit Clock, Pin 2.
The1.544 MHz (or 2.048 MHz) transmit clock is input on this pin. TPOS/TNEG or TDATA are
sampled on the falling edge of TCLK.
TDATA - Transmit Data, Pin 3. (Extended Hardware Mode)
Transmitter NRZ input data which passes through the line code encoder, and is then driven on to
the line through TTIP and TRING. TDATA is sampled on the falling edge of TCLK.
TPOS, TNEG - Transmit Positive Data, Transmit Negative Data, Pins 3 and 4. (Hardware and
Host Modes)
Inputs for clock and data to be transmitted. The signal is driven on to the line through TTIP and
TRING. TPOS and TNEG are sampled on the falling edge of TCLK. A TPOS input causes a
positive pulse to be transmitted, while a TNEG input causes a negative pulse to be transmitted.
DS155PP2
23
CS61577
TTIP, TRING - Transmit Tip, Transmit Ring, Pins 13 and 16.
The AMI signal is driven to the line through these pins. The transmitter output is designed to
drive a 25 Ω load between TTIP and TRING. A transformer is required as shown in Table A1.
Status
AIS - Alarm Indication Signal, Pin 11. (Extended Hardware Mode)
AIS goes high when unframed all-ones condition (blue alarm) is detected, using the detection
criteria of less than three zeros out of 2048 bit periods.
BPV- Bipolar Violation Strobe, Pin 6. (Extended Hardware Mode)
BPV strobes high when a bipolar violation is detected in the received signal. B8ZS (or HDB3)
zero substitutions are not flagged as bipolar violations if the B8ZS (or HDB3) decoder has been
enabled.
DPM - Driver Performance Monitor, Pin 11. (Hardware and Host Modes)
DPM goes high if no activity is detected on MTIP and MRING.
LOS - Loss of Signal, Pin 12.
LOS goes high when 175 consecutive zeros have been received. LOS returns low when 3 ones
are received within 32 bit periods with no more than 15 consecutive zeros. When in the loss of
signal state RPOS/RNEG or RDATA are forced low, and ACLKI (if present) is output on RCLK
via the jitter attenuator. If ACLKI is not present during LOS, RCLK is forced to the center
frequency of the crystal oscillator.
MTIP, MRING - Monitor Tip, Monitor Ring, Pins 17 and 18. (Hardware and Host Modes)
These pins are normally connected to TTIP and TRING and monitor the output of a line interface
IC. If the INT pin in the host mode is used, and the monitor is not used, writing "clear DPM" to
the serial interface will prevent an interrupt from the driver performance monitor.
24
DS155PP2
CS61577
15
28
28 pin
Plastic DIP
E1
1
14
D
A
SEATING
PLANE
B1
A1
L
∝
e1
B
C
eA
NOTES:
1. POSITIONAL TOLERANCE OF LEADS SHALL BE WITHIN
0.25mm (0.010") AT MAXIMUM MATERIAL CONDITION, IN
RELATION TO SEATING PLANE AND EACH OTHER.
2. DIMENSION eA TO CENTER OF LEADS WHEN FORMED PARALLEL.
3. DIMENSION E1 DOES NOT INCLUDE MOLD FLASH.
MILLIMETERS
INCHES
DIM MIN NOM MAX MIN NOM MAX
3.94 4.32 5.08 0.155 0.170 0.200
A
A1 0.51 0.76 1.02 0.020 0.030 0.040
0.36 0.46 0.56 0.014 0.018 0.022
B
B1 1.02 1.27 1.65 0.040 0.050 0.065
0.20 0.25 0.38 0.008 0.010 0.015
C
36.45 36.83 37.21 1.435 1.450 1.465
D
E1 13.72 13.97 14.22 0.540 0.550 0.560
e1 2.41 2.54 2.67 0.095 0.100 0.105
eA 15.24
15.87 0.600
0.625
L
3.18
0.150
3.81 0.125
0°
15°
15°
0°
∝
28-pin PLCC
28
E1 E
DIM
A
MILLIMETERS
INCHES
MIN NOM MAX
MIN NOM MAX
4.20
4.45
4.57 0.165 0.175 0.180
A1
2.29
2.79
3.04 0.090 0.110 0.120
B
0.33
0.41
0.53 0.013 0.016 0.021
D/E 12.32 12.45 12.57 0.485 0.490 0.495
D1
D1/E1 11.43 11.51 11.58 0.450 0.453 0.456
D
D2/E2 9.91 10.41 10.92 0.390 0.410 0.430
e
B
1.19
1.27
1.35 0.047 0.050 0.053
e
A1
A
D2/E2
DS155PP2
25
CS61577
APPLICATIONS
+5V
+
68 µF
RGND
28
Control
&
Monitor
1
12
11
+
0.1 µF
CLKE
21
RV+
1.0 µF
TGND
15
TV+
SCLK
ACLKI
CS
LOS
INT
DPM
SDI
SDO
RV+
5
Frame
Format
Encoder/
Decoder
RPOS
6
RNEG
8
RCLK
4
2
9
XTL
10
100 kΩ
27
26
µP
Serial
Port
23
24
25
MODE
7
3
+5V
CS61577
IN
HOST
MODE
TPOS
RTIP
R1
RRING
20
MTIP
17
MRING
18
TNEG
TCLK
TRING
XTALIN
XTALOUT
RGND
22
1
19
TGND
14
TTIP
R2
2
3
RECEIVE
6 LINE
5
2CT:1
PE-65351
16
0.47 µF
2
13
6
1
TRANSMIT
5 LINE
1:2CT
PE-65351
Figure A1. T1 Host Mode Configuration
Frequency
MHz
1.544 (T1)
2.048 (E1)
Crystal
XTL
CXT6176
CXT8192
Cable
Ω
100
120
75
LEN2/1/0
R3
Ω
0/1/1 - 1/1/1
0/0/0
0/0/0
0/0/1
not used
not used
4.4
not used
R1 and R2
Ω
200
240
150
Table A1. External Component Values
Line Interface
Figures A1-A3 show typical T1 and E1 line interface application circuits. Table A1 shows the
external components which are specific to each
application. Figure A1 illustrates a T1 interface in
the Host Mode. Figure A2 illustrates a 120 Ω E1
interface in the Hardware Mode. Figure A3 illustrates a 75 Ω E1 interface in the Extended
Hardware Mode.
26
The 1:2 receiver transformer has a grounded center tap on the IC side. Resistors R1 and R2
between the RTIP and RRING pins to ground
provide the termination for the receive line. The
transmitter also uses a 1:2 transformer. A 0.47 µF
capacitor is required in series with the transmit
transformer primary. This capacitor is needed to
prevent any output stage imbalance from resulting
in a DC current through the transformer primary.
This current might saturate the transformer producing an output offset level shift.
DS155PP2
CS61577
+5V
+
68 µF
RGND
Control
&
Monitor
28
TAOS
1
ACLKI
RV+
TGND
15
TV+
RLOOP
LEN0
23
27
LLOOP
LEN1
24
12
LOS
LEN2
25
11
DPM
RTIP
19
7
MODE
CS61577
IN
HARDWARE
MODE
RPOS
Line
Length
Setting
1
R1
R2
2
3
6
RNEG
8
RCLK
3
TPOS
MTIP
17
4
TNEG
MRING
18
2
TCLK
TRING
16
0.47 µF
2
TTIP
13
6
9
XTL
21
1.0 µF
26
5
Frame
Format
Encoder/
Decoder
+
0.1 µF
10
RRING
XTALIN
XTALOUT
RGND
22
20
RECEIVE
6 LINE
5
2CT:1
PE-65351
1
TRANSMIT
5 LINE
1:2CT
PE-65351
TGND
14
Figure A2. 120 Ω, E1 Hardware Mode Configuration
+5V
+
68 µF
RGND
Control
&
Monitor
Frame
Format
Encoder/
Decoder
17
RCODE
18
PCS
6
21
RV+
1.0 µF
TGND
15
TV+
BPV
LEN0
23
28
TAOS
LEN1
24
1
ACLKI
LEN2
25
RTIP
19
26
RLOOP
27
LLOOP
12
LOS
11
AIS
5
MODE
4
TCODE
7
RDATA
8
RCLK
3
TDATA
2
9
XTL
+
0.1 µF
10
CS61577
IN
EXTENDED
HARDWARE
MODE
TCLK
1
R1
RRING
20
R2
RECEIVE
6 LINE
5
TRING
16
0.47 µF
2
TTIP
13
6
R3
RGND
22
2
3
2CT:1
PE-65351
XTALIN
XTALOUT
Line
Length
Setting
TGND
14
1
TRANSMIT
5 LINE
1:2CT
PE-65351
Note:
R3 is used for LEN2/1/0 = 0/0/0, but
not required with LEN2/1/0 = 0/0/1.
Figure A3. 75 Ω, E1 Extended Hardware Mode Configuration
DS155PP2
27
CS61577
Transformers
Selecting an Oscillator Crystal
Recommended transmitter and receiver transformer specifications are shown in Table A2. The
transformers in Table A3 have been tested and
recommended for use with the CS61577. Refer to
the "Telecom Transformer Selection Guide" for
detailed schematics which show how to connect
the line interface IC with a particular transformer.
Specific crystal parameters are required for
proper operation of the jitter attenuator. It is recommended that the Crystal Semiconductor
CXT6176 crystal be used for T1 applications and
the CXT8192 crystal be used for E1 applications.
Turns Ratio
Primary
Inductance
Primary Leakage
Inductance
Secondary Leakage
Inductance
Interwinding
Capacitance
ET-constant
1:2 CT ± 5%
600 µH min. @ 772 kHz
1.3 µH max. @ 772 kHz
dual
1:2CT
dual
1:2CT
1:2CT
In some applications it is desirable to attenuate
jitter from the signal to be transmitted. A
CS61577 in local loopback mode can be used as a
jitter attenuator. The inputs to the jitter attenuator
are TPOS, TNEG, TCLK. The outputs from the
jitter attenuator are RPOS, RNEG and RCLK.
0.4 µH max. @ 772 kHz
Line Protection
23 pF max.
16 V-µs min. for T1
12 V-µs min. for E1
Table A2. Transformer Specifications
Turns
Ratio(s)
1:2CT
Transmit Side Jitter Attenuation
Secondary protection components can be added
to provide lightning surge and AC power-cross
immunity. Refer to the "Telecom Line Protection
Application Note" for detailed information on the
different electrical safety standards and specific
application circuit recommendations.
Manufacturer
Part Number
Package Type
Pulse Engineering
Schott
Bel Fuse
Pulse Engineering
Bel Fuse
Pulse Engineering
Bel Fuse
Pulse Engineering
PE-65351
67129300
0553-0013-HC
PE-64951
0553-0013-1J
PE-65761
S553-0013-03
PE-65835
1.5 kV through-hole, single
1.5 kV through-hole, dual
1.5 kVsurface-mount, dual
3 kV through-hole, single
EN60950, EN41003 approved
Table A3. Recommended Transformers
28
DS155PP2
CS61577
Interfacing The CS61577 With the CS62180B
T1 Transceiver
To interface with the CS62180B, connect the devices as shown in Figure A5. In this case, the line
interface and CS62180B are in host mode controlled by a microprocessor serial interface. If the
line interface is used in Hardware Mode, then the
line interface RCLK output must be inverted before being input to the CS62180B. If the
CS61577 is used in Extended Hardware Mode,
the RCLK output does not have to be inverted before being input to the CS62180B.
TO HOST CONTROLLER
1.544 MHz
CLOCK
SIGNAL
ACLK
SCLK
TCLK
SDO
TPOS
TPOS
SDI
TNEG
TNEG
SCLK
TCLK
SDO
SDI
100k
CS
INT
CS
RNEG
RNEG
CLKE
RPOS
RPOS
MODE
RCLK
RCLK
CS62180B
V+
22k
V+
CS61577
Figure A4. Interfacing the CS61577 with a CS62180B
(Host Mode)
DS155PP2
29
• Notes •
CDB61534, CDB61535, CDB61535A, CDB6158,
CDB6158A, CDB61574, CDB61574A, CDB61575,
CDB61577, CDB615304A, & CDB61305A
Line Interface Evaluation Board
Features
General Description
•
• All Required Components for Complete
The evaluation board includes a socketed line interface
device and all support components necessary for
evaluation. The board is powered by an external 5 Volt
supply.
Socketed Line Interface Device
Line Interface Evaluation
• Configuration by DIP Switch or Serial
Interface
Status Indicators for Alarm
• LED
Conditions
The board may be configured for 100 Ω twisted-pair
T1, 75 Ω coax E1, or 120 Ω twisted-pair E1 operation.
Binding posts are provided for line connections. Several BNC connectors are available to provide system
clocks and data I/O. Two LED indicators monitor device alarm conditions. The board supports all line
interface operating modes.
ORDERING INFORMATION:
CDB61534, CDB61535. CDB61535A,
CDB6158,
CDB6158A, CDB61574,
CDB61574A, CDB61575, CDB61577,
CDB61304A, CDB61305A
• Support for Host, Hardware, and
Extended Hardware Modes
+5V
0V
Mode Select
Circuit
Reset
Circuit
TTIP
Serial Interface
Control Circuit
Hardware
Control Circuit
LED Status
Indicators
ACLKI
TCLK
TPOS
(TDATA)
TNEG
(TCODE)
TRING
CS61534,
CS61535,
CS61535A,
CS6158,
CS6158A,
CS61574,
CS61574A,
CS61575,
CS61577,
CS61304A
or
CS61305A
RTIP
RRING
XTL
RCLK
RPOS
(RDATA)
RNEG
(BPV)
Crystal Semiconductor Corporation
P.O. Box 17847, Austin, TX 78760
(512) 445-7222 FAX: (512) 445-7581
SEP ’95
DS40DB3
31
LINE INTERFACE EVALUATION BOARD
POWER SUPPLY
As shown on the evaluation board schematic in
Figure 1, power is supplied to the evaluation
board from an external +5 Volt supply connected
to the two binding posts labeled +5V and GND.
Transient suppressor D10 protects the components on the board from over-voltage damage and
reversed supply connections. The recommended
power supply decoupling is provided by C1, C2
and C3. Ceramic capacitor C1 and electrolytic capacitor C2 are used to decouple RV+ to RGND.
Capacitor C3 decouples TV+ to TGND. The TV+
and RV+ power supply traces are connected at the
device socket U1. A ground plane on the component side of the evaluation board insures optimum
performance.
BOARD CONFIGURATION
Pins on line interface device U1 with more than
one pin name have different functions depending
on the operating mode selected. Pin names not
enclosed in parenthesis or square brackets describe the Hardware mode pin function. Pin
names enclosed in parenthesis describe the Extended Hardware mode pin function. Pin names
enclosed in square brackets describe the Host
mode pin function.
JUMPER
JP1
JP2, JP6, JP7
JP3
JP4
JP5
JP8
POSITION
A-A
B-B
IN
OUT
C-C
D-D
E-E
F-F
IN
OUT
Table 1 explains how to configure the evaluation
board jumpers depending on the device installed
and the desired operating mode. Mode selection
is accomplished with slide switch SW1 and jumpers JP2, JP6, and JP7. The CS61535A,
CS61574A, CS61575, CS61577, CS61304A, and
CS61305A support the Hardware, Extended
Hardware, and Host operating modes. The
CS61534, CS61535, and CS61574 support the
Hardware and Host operating modes. The
CS6158 and CS6158A only support the Hardware
operating mode.
Hardware Mode
In the Hardware operating mode, the line interface is configured using DIP switch S2. The digital control inputs to the device selected by S2 include: transmit all ones (TAOS), local loopback
(LLOOP), remote loopback (RLOOP), and transmit line length selection (LEN2,LEN1,LEN0).
Closing a DIP switch on S2 towards the label sets
the device control pin of the same name to logic 1
(+5 Volts). Note that S2 switch positions TCODE
and RCODE have no function in Hardware mode.
In addition, the host processor interface connector
JP1 should not be used in the Hardware mode.
Two LED status indicators are provided in Hardware mode. The LED labeled DPM (AIS) illuminates when the line interface asserts the Driver
FUNCTION SELECTED
Connector for external processor in Host operating mode.
Extended Hardware operating mode.
Hardware or Host operating modes.
Hardware or Extended Hardware operating modes.
Host operating mode.
Connects the ACLKI BNC input to pin 1 of device.
Grounds the ACLKI BNC input through 51Ω resistor R1.
Transmit line connection for all applications except those listed for "F-F" on the next line.
75Ω coax E1 applications using the Schott 12932/12532 or PE-65389/65566 at transformer T1.
Shorts resistor R2 for all applications except those listed for "OUT" on the next line.
Inserts resistor R2 for 75Ω coax E1 applications using the CS61534, 35, 58, 74, or 77.
Table 1. Evaluation Board Jumper Settings
32
DS40DB3
LINE INTERFACE EVALUATION BOARD
RV+
RV+
+5V
C2
0.1mF
D10
P6KE
GND
(0V)
Prototyping
Area
C1
68mF
+
C3
1 mF
RV+
15
TV+
Pin 6
RNEG
(BPV)
6 RNEG (BPV)
RCLK
8 RCLK
TCLK
2 TCLK
RCLK
TCLK
Pin 3
TPOS
(TDATA)
RV+
R15
100Ω
XTALOUT
{CS6158/58A: NC}
B
TNEG
JP2
A
S2
C
Pin 4
B
RTIP
RRING
TNEG (TCODE)
A
MRING (PCS)
23 LEN0 [INT]
24
LEN1 [SDI]
25
LEN2 [SD0]
26
RLOOP [CS]
27
LLOOP [SCLK]
28
TAOS [CKLE]
LEN2/SD0
RLOOP/CS
LLOOP/SCLK
JP3
TAOS/CLKE
INT
SDI
SDO
CS
SCLK
TRING
MTIP (RCODE)
D8
R14
4.7kW
SIP
C4 0.047mF
7
RV+
5
R16
1kΩ
1
2
RTIP
R9
200W
RRING
TTIP
13
Pin 18
18
B
JP6
B
A
0.47 mF
C5
16
Pin 17
17
B
JP7
B
JP8
E
JP5
TTIP
E
FF
T1
(see Table 2) TRING
A
R2
4.4W
11
(Used only for E1 75W
applications with the CS61534,
CS61535, CS6158, CS61574,
OR CS61577)
LOS
12
RV+
DPM RV+
(AIS)
LOS
Q2
2N2222
Q1
2N2222
LED
D2
LED
D3
R5
470Ω
R6
470Ω
MODE
3
T2
(see Table 2)
2:1
20
A
MODE
SW1
8
Change R9 and R10 for E1 operation
TRING A
MODE DPM (AIS)
5
6
RTIP
19
RRING
ACLKI
TTIP
LEN1/SDI
S1
RESET
R4
221kW
10
U1
4
TCODE
LEN0/INT
D9
1N914
E1: CXT8192
T1: CXT6176
(not included for CS6158/58A)
R10
200W
RCODE
JP1
9
7 RPOS (RDATA)
1
C
R13 (only included for CS6158/58A)
1kW
XTALIN
{CS6158/58A: RT}
ACLKI
R1 51.1Ω D JP4 D
ACLKI
21
RV+
22
RGND
3 TPOS (TDATA)
Pin 7
RPOS
(RDATA)
14
TGND
U1: CS61534, CS61535,
CS61535A, CS6158,
CS6158A, CS61574,
CS61574A, CS61575,
CS61577, CS61304A,
OR CS61305A
4
R18 R17
10k W 10k W
HOST:3-1,6-8
EXT HW: 3-2, 6-7
HW: 3-4, 6-5
Figure 1. Evaluation Board Schematic
DS40DB3
33
LINE INTERFACE EVALUATION BOARD
Performance Monitor alarm. The LED labeled
LOS illuminates when the line interface receiver
has detected a loss of signal.
Extended Hardware Mode
In the Extended Hardware operating mode, the
line interface is configured using DIP switch S2.
The digital control inputs to the device selected
by S2 include: transmit all ones (TAOS), local
loopback (LLOOP), remote loopback (RLOOP),
transmit line length selection (LEN2, LEN1,
LEN0), transmit line code (TCODE), and receive
line code (RCODE). Closing a DIP switch (moving it towards the S2 label) sets the device control
pin of the same name to logic 1 (+5 Volts). Note
that the TCODE and RCODE options are active
low and are enabled when the switch is moved
away from the S2 label. The parallel chip select
input PCS is tied to ground in Extended Hardware mode to enable the device to be reconfigured when S2 is changed. In addition, the host
processor interface connector JP1 should not be
used in Extended Hardware mode.
Two LED status indicators are provided in Extended Hardware mode. The LED labeled DPM
(AIS) illuminates when the line interface detects
the receive blue alarm (AIS). The LED labeled
LOS illuminates when the line interface receiver
has detected a loss of signal.
Host Mode
In the Host operating mode, the line interface is
configured using a host processor connected to
the serial interface port JP1. The S2 switch position labeled CLKE selects the active edge of
SCLK and RCLK. Closing the CLKE switch selects RPOS and RNEG to be valid on the falling
edge of RCLK and SDO to be valid on the rising
edge of SCLK as required by the CS2180B T1
framer.
All other DIP switch positions on S2 should be
open (logic 0) to prevent shorting of the serial in34
terface signals. Resistor R15 is a current limiting
resistor that prevents the serial interface signals
from being shorted directly to the +5 Volt supply
if any S2 switch, other than CLKE, is closed.
Jumper JP3 should be out so the INT pin may be
externally pulled-up at the host processor interrupt pin.
Two LED status indicators are provided in Host
mode. The LED labeled DPM (AIS) illuminates
when the line interface asserts the Driver Performance Monitor alarm. The LED labeled LOS
illuminates when the line interface receiver has
detected a loss of signal.
Manual Reset
A manual reset circuit is provided that can be
used in Hardware and Extended Hardware
modes. The reset circuit consists of S1, R4, R16,
C4, D8, and D9. Pressing switch S1 forces both
LLOOP and RLOOP to a logic 1 and causes a
reset. A reset is only necessary for the CS61534
device to calibrate the center frequency of the receiver clock recovery circuit. All other line interface units use a continuously calibrated clock recovery circuit that eliminates the reset requirement.
TRANSMIT CIRCUIT
The transmit clock and data signals are supplied
on BNC inputs labeled TCLK, TPOS(TDATA),
and TNEG. In the Hardware and Host operating
modes, data is supplied on the TPOS(TDATA)
and TNEG connectors in dual NRZ format. In the
Extended Hardware operating mode, data is supplied in NRZ format on the TPOS(TDATA) connector and TNEG is not used.
The transmitter output is transformer coupled to
the line through a transformer denoted as T1 in
Figure 1. The signal is available at the TTIP and
TRING binding posts. Capacitor C5 is the recommended 0.47 µF DC blocking capacitor.
DS40DB3
LINE INTERFACE EVALUATION BOARD
The evaluation board supports 100Ω twisted-pair
T1, 75Ω coax E1, and 120Ω twisted-pair E1 operation. The CDB61534, CDB61535, CDB6158,
CDB61574, and CDB61577 are supplied from
the factory with a 1:2 transmit transformer that
may be used for all T1 and E1 applications. The
CDB61 53 5A, CDB61 58A, CDB61574A,
CDB61575, CDB61304A, and CDB61305A are
supplied with a 1:1.15 transmit transformer installed for T1 applications. An additional 1:1:1.26
transformer for E1 applications is provided with
the board. This transformer requires JP5 to be
jumpered across F-F for 75Ω coax E1 applications.
The CDB6 15 34 , CDB6 15 35 , CDB6158,
CDB61574, and CDB61577 require the JP8
jumper to be out for 75Ω coax E1 applications.
This inserts resistor R2 to reduce the transmit
pulse amplitude and meet the 2.37 V nominal
pulse amplitude requirement in CCITT G.703. In
addition, R2 increases the equivalent load impedance across TTIP and TRING.
The recovered clock and data signals are available on BNC outputs labeled RCLK,
RPOS(RDATA), and RNEG(BPV). In the Hardware and Host operating modes, data is output on
the RPOS(RDATA) and RNEG(BPV) connectors
in dual NRZ format. In the Extended Hardware
operating mode, data is output in NRZ format on
the RPOS(RDATA) connector and bipolar violations are reported on the RNEG(BPV) connector.
QUARTZ CRYSTAL
A quartz crystal must be installed in socket Y1 for
all devices except the CS6158 and CS6158A. A
Crystal Semiconductor CXT6176 crystal is recommended for T1 operation and a CXT8192 is
recommended for E1 operation. The evaluation
board has a CXT6176 installed at the factory and
a CXT8192 is also provided with the board.
The CDB6158 and CDB6158A have resistor R13
installed instead of a crystal. This connects the RT
pin of the device to the +5 Volt supply.
RECEIVE CIRCUIT
ALTERNATE CLOCK INPUT
The receive line interface signal is input at the
RTIP and RRING binding posts. The receive signal is transformer coupled to the line interface device through a center-tapped 1:2 transformer. The
transformer produces ground referenced pulses of
equal amplitude and opposite polarity on RTIP
and RRING.
The ACLKI BNC input provides the alternate
clock reference for the line interface device
(ACLK for the CS61534) when JP4 is jumpered
across C-C. This clock is required for the
CS61534, CS61535, CS6158, and CS6158A operation but is optional for all other line interface
devices. If ACLKI is provided, it may be desirable to connect both C-C and D-D positions on
JP4 to terminate the external clock source providing ACLKI with the 51Ω resistor R1. If ACLKI is
optional and not used, connector JP4 should be
jumpered across D-D to ground pin 1 of the device through resistor R1.
The receive line interface is terminated by resistors R9 and R10. The evaluation boards are supplied from the factory with 200Ω resistors for terminating 100Ω T1 twisted-pair lines. Resistors
R9 and R10 should be replaced with 240Ω resistors for terminating 120Ω E1 twisted-pair lines or
150Ω resistors for terminating 75Ω E1 coaxial
lines. Two 243Ω resistors and two 150Ω resistors
are included with the evaluation board for this
purpose.
DS40DB3
TRANSFORMER SELECTION
To permit the evaluation of other transformers,
Table 2 lists the transformer and line interface device combinations that can be used in T1 and E1
35
LINE INTERFACE EVALUATION BOARD
applications. A letter at the intersection of a row
and column in Table 2 indicates that the selected
transformer is supported for use with the device.
The transformer is installed in the evaluation
board with pin 1 positioned to match the letter
illustrated on the drawing in Table 2. For example, the Pulse Engineering PE-65388 transformer
may be used with the transmitter of the CS61575
device for 100Ω T1 applications only (as indicated by note 3) when installed in transformer
socket T1 with pin 1 at position D (upper right).
4. To avoid damage to the external host controller
connected to JP1, all S2 switch positions (except
CLKE) should be open. In the Host operating
mode, the CLKE switch selects the active edge of
SCLK and RCLK.
PROTOTYPING AREA
A prototyping area with power supply and ground
connections is provided on the evaluation board.
This area can be used to develop and test a variety of additional circuits like a data pattern generator, CS2180B framer, system synchronizer PLL,
or specialized interface logic.
EVALUATION HINTS
1. Properly terminate TTIP/TRING when evaluating the transmit output signal. For more information concerning pulse shape evaluation, refer to
the Crystal application note entitled "Measurement and Evaluation of Pulse Shapes in T1/E1
Transmission Systems."
2. Change the receiver terminating resistors R9
and R10 when evaluating E1 applications. Resistors R9 and R10 should be replaced with 240Ω
resistors for terminating 120Ω E1 twisted-pair
lines or 150Ω resistors for terminating 75Ω E1
coaxial lines. Two 243Ω resistors and two 150Ω
resistors are included with the evaluation board
for this purpose.
3. Closing a DIP switch on S2 towards the label
sets the device control pin of the same name to
logic 1 (+5 Volts).
36
DS40DB3
LINE INTERFACE EVALUATION BOARD
LINE INTERFACE UNIT
TRANSFORMER
(Turns Ratio)1,2
’34
’35
’35A
’58
’58A
’74,’77
’74A
’75
RX TX RX TX RX TX RX TX RX TX RX TX RX TX RX TX
A D A D A
A D A
A D A
A
B C B C B
B C B
B C B
B
D3
D3
D3
D3
3
3
3
C
C
C
C3
D4
D4
D4
D4
4
4
4
C
C
C
C4
E
E
E
E
E
E
E
E
E3
E3
E3
E3
3
3
3
E
E
E
E3
E4
E4
E4
E4
4
4
4
E
E
E
E4
PE-65351 (1:2CT)
Schott 12930 (1:2CT)
PE-65388 (1:1.15)
Schott 12931 (1:1.15)
PE-65389 (1:1:1.26)
Schott 12932 (1:1:1.26)
PE-64951 (dual 1:2CT)
Schott 11509 (dual 1:2CT)
PE-65565 (dual 1:1.15 & 1:2CT)
Schott 12531 (dual 1:1.15 & 1:2CT)
PE-65566 (dual 1:1:1.26 & 1:2CT)
Schott 12532 (dual 1:1:1.26 & 1:2CT)
’304A,
’305A
RX TX
A
B
D3,5
C3,5
D4,5
C4,5
E3,5
E3,5
E4,5
E4,5
NOTES:
1. A letter at the intersection of a row and column in Table 2 indicates
that the selected transformer is supported for use with the device.
The transformer is installed in the evaluation board with pin 1 positioned to match the letter illustrated in the drawing to the left.
T2
T2
A
B
2.
D
3. For use in 100Ω T1 twisted-pair applications only.
4.
C
E
T1
T1
The receive transformer (RX) is soldered at location T2 on the
evaluation board and is used for all applications. The transmit
transformer (TX) is socketed at location T1 on the evaluation
board and may be changed according to the application.
For use in 75Ω and 120Ω E1 applications only. Place jumper JP5
in position F-F for 75Ω E1 applications requiring a 1:1 turns ratio.
5. Transmitter return loss improves when using a 1:2 turns ratio transformer with the appropriate transmit resistors.
Table 2. Transformer Applications
DS40DB3
37
LINE INTERFACE EVALUATION BOARD
Figure 2. Silk Screen Layer (NOT TO SCALE)
38
DS40DB3
LINE INTERFACE EVALUATION BOARD
Figure 3. Top Ground Plane Layer (NOT TO SCALE)
DS40DB3
39
LINE INTERFACE EVALUATION BOARD
Figure 4. Bottom Trace Layer (NOT TO SCALE)
40
DS40DB3
• Notes •
• Notes •
• Notes •
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