INFINEON PEB22320N

ICs for Communications
Primary Rate Access Clock Generator and Transceiver
PRACT
PEB 22320
Version 2.1
Data Sheet 04.95
PEB 22320
Revision History
Current Version: 04.95
Previous Version:
05.93
Page
Subjects (changes since last revision)
10
Architecture of the PRACT
14
Input Jitter Specification
16
Jitter Attenuator Block Diagram
17
Clock- and Synchronization Table
18
Jitter Attenuation Characteristics
23
Master/Slave Selection
24
Reset
28
Delay Times
29
DC Characteristics
31
Recommended Oscillator Circuits
32, 33
Crystal Tuning Range
Data Classification
Maximum Ratings
Maximum ratings are absolute ratings; exceeding only one of these values may cause irreversible
damage to the integrated circuit.
Characteristics
The listed characteristics are ensured over the operating range of the integrated circuit. Typical
characteristics specify mean values expected over the production spread. If not otherwise specified,
typical characteristics apply at TA = 25 °C and the given supply voltage.
Operating Range
In the operating range the functions given in the circuit description are fulfilled.
For detailed technical information about “Processing Guidelines” and “Quality Assurance” for
ICs, see our Product Overview “ICs for Communications”
PEB 22320
General Information
Page
Table of Contents
1
1.1
1.2
1.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Pin Configuration (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Pin Definitions and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
System Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
2
2.1
2.1.1
2.1.2
2.1.3
2.1.4
2.2
2.2.1
2.2.2
2.3
2.4
2.5
2.6
2.7
2.8
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Basic Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Clock and Data Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Input Jitter Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Jitter Attenuator and Clock Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Basic Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Output Jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Local Loopback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Remote Loopback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Bypass Jitter Attenuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Microprocessor Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Receiver Loss of Signal Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Master/Slave Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
3
3.1
3.1.1
3.1.2
3.2
Operational Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Reset with CS Pin Fixed to VSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Reset Using CS Pin to Latch Programming (a controller is used) . . . . . . . . .26
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
4
4.1
4.2
4.2.1
4.2.2
4.3
4.4
4.5
4.6
4.6.1
4.6.2
4.6.3
4.6.4
Electrical Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Delay Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Delay from XDIP/XDIN to XL1/XL2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Delay from RL1/RL2 to RDOP/RDON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Recommended Oscillator Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Dual Rail Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
System Clock Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Microprocessor Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
XTAL Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Semiconductor Group
3
PEB 22320
4.7
4.8
Pulse Templates - Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Overvoltage Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
5
Package Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
IOM®, IOM®-1, IOM®-2, SICOFI®, SICOFI®-2, SICOFI®-4, SICOFI®-4µC, SLICOFI®, ARCOFI® , ARCOFI®-BA,
ARCOFI®-SP, EPIC®-1, EPIC®-S, ELIC®, IPAT®-2, ITAC®, ISAC®-S, ISAC®-S TE, ISAC®-P, ISAC®-P TE, IDEC®,
SICAT®, OCTAT®-P, QUAT®-S are registered trademarks of Siemens AG.
MUSAC™-A, FALC™54, IWE™, SARE™, UTPT™, ASM™, ASP™ are trademarks of Siemens AG.
Purchase of Siemens I2C components conveys a license under the Philips’ I2C patent to use the components in
the I2C-system provided the system conforms to the I2C specifications defined by Philips. Copyright Philips 1983.
Semiconductor Group
4
Primary Rate Access Clock Generator
and Transceiver
PRACT
PEB 22320
Preliminary Data
1
CMOS
Features
• ISDN line interface for 1544 and 2048 kbit/s (T1 and
CEPT)
• Data and clock recovery
• Transparent to ternary codes
• Low transmitter output impedance for a high return
loss with reasonable protection resistors (CCITT
G.703 requirements for the line input return loss
P-LCC-44
fulfilled)
• Adaptively controlled receiver threshold
• Programmable pulse shape for T1 applications
• Jitter specifications of CCITT I.431 and BELLCORE
TR-NWT-000499 publications met
• Wander and jitter attenuation
• Jitter tolerance of receiver: 0.5 UI s
• Implements local and remote loops for diagnostic purposes
• Monolithic line driver for a minimum of external components
• Low power, reliable CMOS technology
• Loss of signal indication for receiver
• Clock generator for system clocks
Type
Ordering Code
Package
PEB 22320 N
Q67100-A6059
P-LCC-44 (SMD)
The Primary Rate Access Clock Generator and Transceiver PRACT (PEB 22320) is a
monolithic CMOS device which implements the analog receive and transmit line
interface functions to primary rate PCM carriers. It may be programmed or hard wired to
operate in 1.544-Mbit/s (T1) or 2.048-Mbit/s (CEPT) carrier systems.
The PRACT recovers clock and data using an adaptively controlled receiver threshold.
It will meet the requirement of CCITT I.431 and Bellcore TR-NWT-000499 Issue 5,
December 1993 (Transport System Generic Requirements) in case of pulse shape, jitter
tolerance and jitter transfer characteristic.
Semiconductor Group
5
04.95
PEB 22320
Features
Specially designed line interface circuits simplify the tedious task of protecting the device
against overvoltage damage while still meeting the return loss requirements.
The PRACT is suitable for use in a wide range of voice and data applications such as for
connections of digital switches and PBX’s to host computers, for implementations of
primary ISDN subscriber loops as well as for terminal applications. The maximum range
is determined by the maximum allowable attenuation.
In the T1 case the PRACT’s power consumption is mainly determined by the line length
and type of the cable.
Semiconductor Group
6
PEB 22320
Features
3
2
CLK2M
RL2
V DD2
4
V SSR
LL
5
JATT
V DDR
CLK4M
6
RL1
CLK4M
Pin Configuration
(top view)
FSC
1.1
1 44 43 42 41 40
FSC
7
39
CLK2M
LS0
8
38
RCLK
XTAL4
9
37
RDON
XTAL3
10
36
LS1
11
35
RDOP
V SSD
XTAL2
12
34
V DDD
XTAL1
13
33
CS
LS2
14
32
XCLK
CLK16M
15
31
XDIP
CLK12M
16
30
XDIN
SYNC
17
29
XTIP
PRACT
PEB 22320
Semiconductor Group
7
XTIN
RL
MODE
N.C.
XL2
V SSX
N.C.
V SSX
XL1
V DDX
V DDX
18 19 20 21 22 23 24 25 26 27 28
ITP04874
PEB 22320
Features
1.2
Pin Definitions and Functions
Pin Definitions and Functions
Pin No.
Symbol
Input (I)
Function
Output (O)
1
VDD2
O
Reference voltage for tapping the input transformer
2
RL2
I
Line receiver pin 2
3
LL
I
Local loopback:
A high level selects the device for the local
loopback mode.
4
5
CLK4M
CLK4M
O
O
System clock 4.096 MHz inverted and
non-inverted
6
7
FSC
FSC
O
O
8-kHz frame synchronization pulse inverted and
non-inverted
8
LS0
I
Line length select
9
10
XTAL4
XTAL3
O
I
Crystal connection 12.352 MHz
If an external clock generator is used and T1 mode
is selected the PRACT works as a master.
11
LS1
I
Line length select
12
13
XTAL2
XTAL1
O
I
Crystal connection 16.384 MHz
When an external clock is used, normally if the
MODE pin is set high, the PRACT functions as a
master.
14
LS2
I
Line length select
15
CLK16M O
System clock 16.384 MHz
16
CLK12M O
System clock 12.352 MHz
17
SYNC
I
If a clock is detected at the SYNC pin the PRACT
synchronizes to this clock (2.048 MHz for CEPT,
1.544 MHz for T1). (Please refer to table 3).
18, 19
VDDX
I
Positive power supply for transmit subcircuits
20
XL1
O
Line transmit pin 1
21, 25
N.C.
22, 23
VSSX
I
Ground for transmit subcircuits
24
XL2
O
Line transmit pin 2
Semiconductor Group
not connected
8
PEB 22320
Features
Pin Definitions and Functions (cont’d)
Pin No.
Symbol
Input (I)
Function
Output (O)
26
RL
I
Remote loopback:
High level puts the device to the remote loopback
mode.
27
MODE
I
Master/Slave selection
If the MODE pin is set to a low level the PRACT
functions as a slave. (Please refer to table 3)
28
29
XTIN
XTIP
I
I
Positive and negative test data inputs, active low,
full bauded
30
31
XDIN
XDIP
I
I
Positive and negative data inputs, active low, full
bauded
32
XCLK
I/O
If the T1 mode is selected the XCLK is a clock
output with a clock frequency of 1.544 MHz.
Otherwise the XCLK is a clock input whose
frequency is 2.048 MHz. (Please refer to table 3)
33
CS
I
Chip Select:
A low level selects the PEB 22320 for a register
write operation.
34
I
Positive power supply for the digital subcircuits.
35
VDDD
VSSD
I
Power ground supply for digital subcircuits.
36
37
RDOP
RDON
O
O
Receive data output positive and negative, fully
bauded, active low.
38
RCLK
O
Receive clock refer to table 3.
39
40
CLK2M
CLK2M
O
O
System clock 2.048 MHz inverted and
non-inverted.
41
I
Power ground supply for receive subcircuits.
42
VSSR
VDDR
I
Positive power supply for the receive subcircuits.
43
JATT
I
If the JATT pin is set to a low level the jitter
attenuator is bypassed.
44
RL1
I
Line receiver pin 1.
Semiconductor Group
9
PEB 22320
Features
1.3
System Integration
Figure 1 shows the architecture of a primary access board for data transmission. It
exhibits the following functions:
–
–
–
–
–
–
–
–
–
–
Line Interface (PEB 22320, PRACT)
Clock and Data Recovery (PEB 22320, PRACT)
Jitter Attenuation (PEB 22320, PRACT)
Clock Generation (PEB 22320, PRACT)
Coding/Decoding (PEB 2035, ACFA)
Framing (PEB 2035, ACFA)
Elastic Buffer (PEB 2035, ACFA)
Multichannel Protocol Controller (PEB 20320, MUNICH32)
System Adaptation (PEB 20320, MUNICH32)
µP Interface (all devices)
MPU
Memory
MUNICH32
PEB 20320
ACFA
PEB 2035
PC
Interface
TCLK/RCLK TSP/RSP
SYPQ
PRACT
PEB 22320
SCLK
CLK4M FSC FSC CLK2M
4.096 MHz
8 kHz
8 kHz
2.048 MHz
ITS04875
Figure 1
Architecture of the PRACT
Semiconductor Group
10
PEB 22320
Functional Description
Functional Description
MODE
SYNC
JATT
RL1
Receive
Input
RL2
Local Loop
LL
XTIP
Transmit
XTIN
Test Data
Receiver
Clock &
Data
Recovery
Loss of
Signal
Detection
XL1
Transmit
Output
XTAL1, 2, 3, 4
RRCLK
P
N
Jitter Attenuator
&
Clock Generator
LOS
Driver
D/A
XCLK (T1)
System
Clocks
ROM
Timing &
Pulseshaper
Remote Loop
2
XL2
LS0, 1, 2
Figure 2
Functional Block Diagram of the PRACT
Semiconductor Group
11
RL
RCLK
RDOP
RDON
XDIP
XDIN
XCLK
(CEPT)
ITB04876
PEB 22320
Functional Description
2.1
Receiver
2.1.1
Basic Functionality
The receiver recovers data from the ternary coded signal at the ternary interface and
outputs it as 2 unipolar signals at the dual rail interface. One of the lines carries the
positive pulses, the other the negative pulses of the ternary signal.
The signal at the ternary interface is received at both ends of a center-tapped
transformer as shown in figure 3.
.
R L1
t 11
R2
t2
Line
VDD 2
R2
t 12
R L2
ITS00560
Figure 3
Receiver Configuration
The transformer is center-tapped at the PRACT side. The recommended transmission
factors for the different line characteristic impedances are listed in table 1.
Table 1
Recommended Receiver Configuration Values
Application
T1
CEPT
Characteristic
Impedances [Ω]
100
140 (ICOT)
120
75
R2 ± (2.5%) [Ω]
28.7
39.2
60
60
t2 : t1 = t2 : (t11 + t12)
69:52
69:52
69:(26 + 26) 69:(26 + 26)
52:52
41:52
52:(26 + 26) 41:(26 + 26)
Wired in this way the receiver has a return loss
ar > 12 dB
ar > 18 dB
ar > 14 dB
for
for
for
0.025 fb
0.05 fb
1.0 fb
≤f ≤
≤f ≤
≤f ≤
0.05 fb,
1.0 fb and
1.5 fb,
with fb being 2048 kHz. Thus it complies with CCITT G.703.
Semiconductor Group
12
PEB 22320
Functional Description
The receiver is transparent to the logical 1’s polarity and outputs positive logical 1’s on
RDOP and negative logical 1’s on RDON. RDON and RDOP are active low and fully
bauded. The comparator threshold to detect logical 1’s and logical 0’s is automatically
adjusted to be 45% of the peak signal level.
Provided the noise is below 10 µV/√Hz the bit error rate will be less than 10–7.
2.1.2
Clock and Data Recovery
An analog PLL extracts the internal recovered route clock RRCLK from the data stream
received at the RL1 and RL2 lines. The PLL uses as a reference the system clock
CLK16M for CEPT and CLK12M for T1 applications. The clock and data recovery is
tolerant to long strings of consecutive zeros, because the data sampler will continuously
sample data based on its last input. A block diagram of the clock and data recovery
circuit is shown in figure 4.
Data
Sampling
Input Data
derived from RL
1, 2
PD
Filter
Figure 4
Clock and Data Recovery Circuit
Semiconductor Group
13
P
Data
N
VCO
RRCLK
CLK16M (CEPT)
CLK12M (T1)
ITS04877
PEB 22320
Functional Description
2.1.3
Input Jitter Tolerance
The PRACT receiver’s tolerance to input jitter complies to CCITT and Bellcore
requirements for CEPT and T1 application.
Figure 5 shows the curves of the different input jitter specifications stated above as well
as the PRACT performance for the various line codes used at the S1/S2 interfaces.
In figure 5 the curves show that the PRACT at low frequencies has more than 20 dB/
decade fall off, and at high frequencies is in a steady state of 0.5 UI (horizontal).
ITD06576
100
TR-NWT 000499
Cat I
TR-NWT 000499
Cat II
PRACT CEPT
PRACT T1
CCITT G.823
Jitter Input Tolerance
UI
10
1
0.1
1
10
100
1000
10000
Jitter Frequency
Figure 5
Comparison of Input Jitter Specification and PRACT Performance
Semiconductor Group
14
Hz
100000
PEB 22320
Functional Description
Table 2
Jitter Input Tolerance
Frequency
Hz
1
10
20
192.9
500
2400
6430
8000
10000
18000
20000
25000
40000
50000
100000
2.1.4
CCITT G.823
2.9
TR-NWT
000499
Cat I
TR-NWT
000499
Cat II
5
10
PRACT
PRACT
CEPT
T1
90
5.8
70
4.5
1.15
0.95
0.62
0.58
0.55
0.5
0.55
0.55
0.95
0.8
0.58
0.55
0.55
0.5
0.55
0.55
1.5
10
5
1.5
0.3
0.1
0.2
0.1
0.3
Jitter Attenuator and Clock Generator
The jitter attenuator reduces wander and jitter in the recovered clock which are produced
by the line-, clock- and data-recovery characteristics. The attenuator consists of one PLL
with a tunable crystal oscillator and a 288-bit FIFO. To provide for T1 mode a 1.544-MHz
clock (XCLK) and a 2.048-MHz clock (CLK2M) for the system, a second PLL is placed
in series with the first one (refer to figure 6).
If the JATT pin is set to low the FIFO is bypassed and the propagation delay from RL1, 2
to RDOP/RDON is reduced by the pass time of the FIFO.
After loss of signal detection, the internal PLL is synchronized to the 2.048 MHz (CEPT)
provided at the SYNC pin (1.544 MHz in the case of T1). If this SYNC pin is not
connected or connected to logical zero, the PRACT switches automatically to master
operating mode (refer to table 3).
With the MODE pin a master selection is provided. That means if the MODE pin is set to
high the master function is selected in which the VCO’s of the jitter attenuator are
centered (± 50 ppm of the crystal frequencies). If a clock is detected at the SYNC pin the
PRACT automatically synchronized to this clock.
Semiconductor Group
15
PEB 22320
Functional Description
The jitter attenuator meets the jitter transfer requirements of the Bellcore
TR-NWT 000 499 and Rec. I.431 (refer to figure 7 and table 4).
The amount of generated output jitter when no input jitter is shown in table 5.
JATT
FIFO
W
RL1, 2
Clock & Data
Recovery
R
P Data
N Data
RDOP
RDON
RCLK
RRCLK
MODE
SYNC
LOS
12.352 MHz
<_ 193
8 kHz
PD
VCO
<_ 193
<_ 8
<_ 256
12 MHz
1.5 MHz
(XCLK-T1)
T1
16.384 MHz
<_ 256
8 kHz
PD
VCO
<_ 2
<_ 4
2 MHz
4 MHz
Figure 6
Jitter Attenuator Block Diagram
Semiconductor Group
16
16 MHz
ITB04879
1.5 M
1.5 M
1
1
X
X
X
0
1
1
X
X
X
0
1
1
X
X
X
0
1
1
X
X
X
1
1
1
1
1
Semiconductor Group
1
1
1
1
1
1
0
0
0
17
0
0
0
0
0
0
0
0
0
X
1
1
0
0
0
X
1
1
0
0
0
X
1
1
0
0
0
X
1
1
0
0
0
Pin
MODE
CEPT
CEPT
CEPT
CEPT
CEPT
CEPT
T1
T1
T1
T1
T1
T1
CEPT
CEPT
CEPT
CEPT
CEPT
CEPT
T1
T1
T1
T1
T1
T1
Pin
LS0..2
LOS = 0: Input above receiver threshold
LOS = 1: Input below receiver threshold
JATT = 1: Jitter attenuator enabled
JATT = 0: Bypass jitter attenuator
X
0
2M
2M
0
X
X
0
1.5 M
1.5 M
0
X
X
0
2M
2M
0
X
X
0
0
X
0
1
Pin
SYNC
Int. Sig
LOS
Pin
JATT
X
X
N.C.
16 M in
N.C.
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M in
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M Crystal
16 M in
16 M crystal sync. freq. centered
16 M crystal sync. on SYNC
16 M crystal sync. on SYNC
16 M crystal sync. freq. centered
16 M crystal sync. on RRCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M in
16 M crystal sync. freq. centered
16 M crystal sync. on SYNC
16 M crystal sync. on SYNC
16 M crystal sync. freq. centered
16 M crystal sync. on RRCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
16 M crystal sync. on XCLK
System Clocks
4M, 2M, 8K Derived from
Pin
XCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=RRCLK
=2 M
=2 M
=2 M
=2 M
=2 M
=2 M
=1.5 M
=1.5 M
=1.5 M
=1.5 M
=1.5 M
=1.5 M
Pin
RCLK
MODE = 0 Slave mode selected
MODE = 1: Master mode selected
8k
= 8.0 kHz
= don’t care
X
N.C. = No Connection
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
output: 1.5 M sync. on XTAL3
output: 1.5 M freq. centered
output: 1.5 M sync. on SYNC
output: 1.5 M sync. on SYNC
output: 1.5 M, freq. centered
output: 1.5 M sync. on RRCLK
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
input (2 M from ACFA)
output: 1.5 M sync. on XTAL3
output: 1.5 M freq. centered
output: 1.5 M sync. on SYNC
output: 1.5 M sync. on SYNC
output: 1.5 M, freq. centered
output: 1.5 M sync. on RRCLK
RRCLK = Internal recovered route clock
SYNC = 0: Input tied to low
SYNC = 2 M: Input connected to 2 M
SYNC = 1.5 M: Input connected to 1.5 M
Pin
XTAL2
16 M Crystal
Pin
XTAL1
12 M = 12.352 MHz
16 M = 16.384 MHz
4 M = 4.096 MHz
2 M = 2.048 MHz
1.5 M = 1.544 MHz
X
X
X
X
X
X
X
X
N.C
X
X
X
X
12 M in
12 M Crystal
12 M Crystal
12 M Crystal
12 M Crystal
12 M Crystal
X
X
X
X
X
X
X
X
N.C.
Pin
XTAL4
X
X
12 M in
12 M Crystal
12 M Crystal
12 M Crystal
12 M Crystal
12 M Crystal
Pin
XTAL3
PEB 22320
Functional Description
Table 3
Clock and Synchronization Table
PEB 22320
Functional Description
ITD06577
2
0
dB
Jitter Transfer Characteristics
-10
-20
-30
-40
CCITT G.735
CCITT I.431
TR-NWT 000499
Cat I to Cat I
PRACT CEPT
PRACT T1
-50
-60
1
0.1
10
100
1000
10000
Hz
100000
Jitter Frequency
Figure 7
Jitter Attenuation Characteristics
Table 4
Jitter Transfer Characteristics
Frequency
CCITT G. 735
TR-NWT 000499
PRACT
PRACT
Hz
CCITT I.431
Cat I to Cat II
CEPT
T1
0.3
0.00
1
3
10
0.5
0.5
100
Semiconductor Group
– 20.00
– 20.00
– 40.00
0.10
30
40
0.00
18
PEB 22320
Functional Description
Table 4
Jitter Transfer Characteristics (cont’d)
Frequency
CCITT G. 735
TR-NWT 000499
PRACT
PRACT
Hz
CCITT I.431
Cat I to Cat II
CEPT
T1
– 39.40
– 60.00
– 60.00
– -80.00
200
250
300
350
400
– 19.50
9650
1000
1412
2500
– 34.07
3000
10000
15000
– 19.50
– 49.63
Table 5
Generated Output Jitter
Specification
I.431
Measurement Filter Bandwidth
Lower Cutoff
Upper Cutoff
(UI peak to peak)
20 Hz
700 Hz
100 kHz
100 kHz
≤ 0.125
≤ 0.02
8 kHz
40 kHz
40 kHz
≤ 0.02
≤ 0.025
≤ 0.025
PUB 62411 Dez. 90 10 Hz
8 kHz
10 Hz
broad band
ETS 300 011
Semiconductor Group
Output Jitter
40 Hz
100 kHz
19
≤ 0.05
≤ 0.11
PEB 22320
Functional Description
2.2
Transmitter
2.2.1
Basic Functionality
The transmitter transforms unipolar data to ternary (alternate bipolar) return to zero
signals of the appropriate shape. The unipolar data is provided at XDIP (positive pulses)
and XDIN (negative pulses), synchronously with the transmit clock XCLK. XDIP and
XDIN are active low and full bauded. Data is sampled on the falling edge of the input
clock (XCLK). The input clock (XCLK) must be derived from the (system) clocks
generated by the PRACT. This ensures the recommended fixed relationship between
XLCK and internal generated clock (4 times XCLK) for the pulse shaper.
The transmitter includes a programmable pulse shaper to satisfy the requirements of the
AT&T Technical Advisory # 34 at the cross connect point for T1 applications. The pulse
shaper is programmed via the line length selection pins LS0, LS1 and LS2.
For T1 application the line length selection supports both low capacitance cable with a
characteristic line capacitance of C’ ≤ 40 nF/km = 65 nF/mile (e.g. MAT, ICOT) and
higher capacitance cable with a characteristic line capacitance of 40 nF/
km ≤ C’ ≤ 54 nF/km (65 nF/mile ≤ C’ ≤ 87 nF/mile) e.g. ABAM, PIC and PULP cables.
This ensures that for various cable types the signal at the DSX-1 cross connect point
complies with the pulse shape of the AT&T Technical Advisory # 34.
The line length is selected programming the LS0, LS1 and LS2 pins as shown for typical
values in table 6.
Table 6
Line Length Selection
LS2
LS1
LS0
0
0
0
CEPT
0
0
0
1
1
0
T1/G.703
T1
0
1
1
0
1
0
1
1
0
1
1
1
PIC/PULP Cable 24 AWG
range/m
–
ICOT Cable
range/m*
–
0
20
–
–
50
80
0
65
–
–
80
145
T1
T1
60
110
–
–
130
200
130
195
–
–
210
275
1
0
T1
T1
140
210
–
–
230
290
260
325
–
–
340
405
1
T1
270
–
320
390
–
470
Note: * For ICOT-cable the characteristic impedance is 140 Ω
By selecting an all-zero code for LS0, LS1 and LS2 the PRACT can be adapted for
CEPT applications.
Semiconductor Group
20
PEB 22320
Functional Description
The pulse shape according to CCIT G.703 (1544-kbit/s interface) is achieved by using
the same line length selection code as for the lowest T1 cable range. To switch the
device into a low power dissipation mode, XDIP and XDIN should be held high.
The transmitter requires an external step up transformer to drive the line. The
transmission factor and the source serial resistor values can be seen in figure 8 and
table 7 for the various applications.
R1
XL1
t 11
t2
Line
t 12
R1
XL 2
ITS00562
Figure 8
Transmitter Configuration
Table 7
Transmitter Configuration Values
Application
T1
CEPT
Characteristic line impedance
[Ω]
100
140 (ICOT) 120
75
t11 : t2 = t12 : t2
R1 (± 2.5%) [Ω]
26:69
26:69
26:52
26:41
4.3
6
15
15
Wired in this way the transmitter has a return loss
ar > 8 dB
ar > 14 dB
ar > 10 dB
for
for
for
0.025 fb
0.05 fb
1.0 fb
≤f≤
≤f≤
≤f≤
0.05 fb,
1.0 fb and
1.5 fb,
with fb being 2048 kHz (CEPT applications). A termination resistor of 120 Ω is assumed.
In T1 applications the return loss is higher than 10 dB.
Please note, that the transformer ratio at the receiver is half of that at the transmitter. The
same type of transformer can thus be used at the receiver and at the transmitter. At the
transmitter the two windings are connected in parallel, at the receiver in series. Thus,
unbalances are avoided.
Semiconductor Group
21
PEB 22320
Functional Description
2.2.2
Output Jitter
In the absence of any input jitter the PRACT generates the output jitter, which is specified
in table 5.
Note: The generated output jitter on the line is the same as the output jitter of the system
clocks.
2.3
Local Loopback
The local loopback mode disconnects the receive lines RL1 and RL2 from the receiver.
Instead of the signals coming from the line the data provided at XTIP and XTIN are
routed through the receiver. The XDIN and XDIP signals continue to be transmitted on
the line. The local loopback occurs in response to LL going high.
2.4
Remote Loopback
In the remote loopback mode the clock and data recovered from the line inputs RL1 and
RL2 are routed back to the line outputs XL1 and XL2 via the transmitter. As in normal
mode they are also output at RDOP and RDON. XDIP and XDIN are disconnected from
the transmitter.
The remote loopback mode is selected by a high RL signal.
2.5
Bypass Jitter Attenuator
If the JATT pin is set to low the jitter attenuator (FIFO) is bypassed and the propagation
delay from the line to the dual rail interface is reduced by the path time of the FIFO. Also
in this mode the jitter in the system clocks (CLK2M, CLK4M, FSC) is attenuated.
2.6
Microprocessor Interface
The PRACT is fully controlled by six parallel data lines (LS0, LS1, LS2, LL, RL and JATT)
and one control line (CS). To adapt the device to a standard microprocessor interface
the low state of CS is decoded from the microprocessor address, CS, WR and ALE lines.
To hardwire the chip, CS must be fixed to ground.
2.7
Receiver Loss of Signal Indication
In the case that the signal at the line receiver input (pins RL1, RL2) becomes smaller
than Vin ≤ 0.3 VOP loss of signal is indicated. This voltage value corresponds to a line
attenuation of about 14 dB in the CEPT case. This is performed by turning both signals
RDOP, RDON after at least 32 bits simultaneously to 5 V, i.e. a logical 0 on both lines.
The following ACFA processes this indication for the system. In this mode the PRACT
synchronizes to the clock at the SYNC pin.
Semiconductor Group
22
PEB 22320
Functional Description
2.8
Master/Slave Selection
If the MODE pin is set to high and the SYNC pin is not connected or connected to VSS the
PRACT works as a master for the system. The VCO’s of the jitter attenuator are centered
(± 50 ppm of the crystal frequencies) and the system clocks are stable (divided from the
VCO frequencies). If a clock (2.048 MHz for CEPT, 1.544 MHz for T1) is detected at the
SYNC pin the PRACT synchronizes automatically to this clock. In master mode, the
PRACT is independent from the receiver loss of signal detection.
Note: The MODE pin can not be controlled by the µP interface and requires CMOS
levels as input signals. It must always be connected either to VDD or VSS.
A voltage of 2.5 V at the MODE Pin switch the PRACT into test mode.
Semiconductor Group
23
PEB 22320
Operational Description
3
Operational Description
3.1
Reset
After power up resetting the device is necessary to synchronize the internal circuitries.
After reset a stabel RCLK is available after 65536 clock cycles. This results in 32 ms in
CEPT mode and 42.5 ms in T1 mode. A reset can be performed by two ways.
3.1.1
Reset with CS Pin Fixed to VSS
In this reset operation the CS pin is normally hardwired to VSS. Before giving a reset the
operational mode has to be selected (CEPT, T1) by setting the pins LS2, LS1, LS0 to
000 for CEPT-application, to 001 for NTT-application or 001 … 111 for T1 application.
A reset is made by simultaneously setting both RL and LL to high (CS = 0) for at least
1 µs. Reset will be initiated on the falling edge of RL or LL, the one that falls first.
The following figures explain the procedure in some examples.
CS
LS2
LS1
LS0
RL
LL
1µs
1.
2.
1. Start of Reset
2. End of Reset
ITD04881
Figure 9
Resetting PRACT for CEPT Applications
Semiconductor Group
t
24
PEB 22320
Operational Description
CS
LS2
LS1
LS0
RL
LL
JATT
t
1.
2.
1. Start of Reset
2. End of Reset and local loop is initiated
ITD04882
Figure 10
Resetting PRACT for CEPT Applications and Setting Local Loop with Jitter
Attenuation
CS
LS2
LS1
LS0
RL
LL
t
1.
2.
1. Start of Reset
2. End of Reset, regular operation in T1 Mode
3. Remote loop is initiated
3.
ITD04883
Figure 11
Resetting PRACT for T1 Applications (max. line length selected) and Setting
Remote Loop
Note: If the PRACT is initiated for T1 applications the line length selection can be
changed without a new reset.
Semiconductor Group
25
PEB 22320
Operational Description
3.1.2
Reset Using CS Pin to Latch Programming (a controller is used)
Reset is done by setting the pins RL and LL to logical 1 for at least 1 µs and latching
these values into PRACT by a rising edge at pin CS.
The selection of CEPT, T1 applications is achieved by setting the pins LS2, LS1, LS0
simultaneously with the reset to 000 for CEPT application or a T1 line length code
(001 … 111 see table 6). The logical level of the RL, LL, LS2, LS1, LS0, JATT input parts
are latched with the rising edge of the CS. Refer to figure 20.
The following figures explain the procedure in some examples.
CS
RL
JATT
LL
LS0, 1, 2
1 µs
1.
t
2.
1. Start of Reset
2. End of Reset, Regular operation in CEPT Mode
ITD04884
Figure 12
Resetting PRACT for CEPT Applications and Jitter Attenuation
CS
RL
LL
LS0, 1, 2
t
1.
2.
1. Start of Reset
2. End of Reset and setting remote loop
ITD04885
Figure 13
Resetting PRACT for CEPT Application and Setting Remote Loop
Semiconductor Group
26
PEB 22320
Operational Description
CS
RL
LL
LS0, 1, 2
xxx
xxx
001
001
xxx
xxx
010
xxx
t
1.
2.
3.
1. Start of Reset
2. End of Reset and setting line length code, Regular operation in T1 Mode
3. Changing line length code, Regular operation in T1 Mode with
changed line length code
ITD04886
Figure 14
Resetting PRACT for T1 Applications and Changing Line Length Code
CS
RL
LL
LS0, 1, 2
xxx
xxx
111
111
xxx
t
1.
2.
1. Start of Reset
2. End of Reset and setting local loop and
line length code
ITD04887
Figure 15
Resetting PRACT for T1 Application and Setting Local Loop
3.2
Operation
The PRACT is in normal operation as soon as the reset phase is finished. The CS pin is
activated again only when PRACT is reprogrammed (for example setting a loop or
changing line length code). That means CS pin could be kept high for normal operation.
Semiconductor Group
27
PEB 22320
Electrical Specification
4
Electrical Specification
4.1
Absolute Maximum Ratings
Parameter
Symbol
Limit Values
Voltage on any pin with respect to
ground
VS
– 0.4 to VDD + 0.4 V
Ambient temperature under bias
TA
0 to 70
°C
Storage temperature
Tstg
– 65 to 125
°C
4.2
Delay Times
4.2.1
Delay from XDIP/XDIN to XL1/XL2
Unit
The delay from XDIP/XDIN to XL1,XL2 is 770 ns in T1 mode and 860 ns in CEPT mode.
This relates to the falling edge of the XCLK and the leading edge of XL1 or XL2.
4.2.2
Delay from RL1/RL2 to RDOP/RDON
The delay from RL1/RL2 to RDOP/RDON is given with 700 ns in T1 mode and 540 ns in
CEPT mode. This relates to the leading edge of the RL1 or RL2 to the falling edge of
RDOP or RDON.
Semiconductor Group
28
PEB 22320
Electrical Specification
4.3
DC Characteristics
TA = 0 to 70 °C; VDD = 5 V ± 5%, VSS = 0 V
DC Characteristics
Parameter
L-input voltage
H-input voltage
L-output voltage
H-output voltage
H-output voltage
Symbol
VIL
VIH
VOL
VOH
VOH
Limit Values
Unit Test Condition
Pins
V
All
pins
except
MODE,
RLx,
XLx
XTALx,
VDD2,
SYNC
min.
max.
– 0.4
0.8
2.0
VDD + 0.4 V
0.45
V
2.4
V
VDD –
V
IOL = 2 mA
IOH = – 400 µA
IOH = – 100 µA
0.5
µA
Input leakage
current
ILI
Output leakage
current
ILO
Peak voltage of a
mark (CEPT)
VXCEPT
2.7
3.3
V
wired according
figure 8 and table 7
Peak voltage of a
mark (T1)
VXT1
1.8
3.4
V
T1 application:
depending on line
length
Transmitter output RX
impedance
0.3
Ω
Transmitter output IX
current
50
mA
CEPT application
150
mA
T1 application:
depending on line
length
2.5
V
1
0 V < VOUT < VDD to
0V
Receiver input
peak voltage of a
mark
VR1)
0.4
Loss of signal
threshold
VLOS
0.3
Receiver input
threshold
VRTH
Voltage at VDD2
VDD2
Semiconductor Group
0 V < VIN < VDD to
0V
2.4
V
45
%
2.6
V
29
XL1,
XL2
RL1,
RL2
PEB 22320
Electrical Specification
DC Characteristics (cont’d)
Parameter
L-input voltage
H-input voltage
Symbol
VXTALIL
VXTALIH
Limit Values
Unit Test Condition
Pins
XTAL1,
XTAL2,
XTAL3,
XTAL4
min.
max.
– 0.4
1.0
V
4.0
VDD +
V
0.4
1
µA
0 V ≤ VIN ≤ VDD to
0V
40
110
mA
CEPT application
55
190
mA
T1 application,
min value for all
zeros, max value
for all ones and
max. line length for
T1 appl.
VIL
– 0.4
0.8
V
VIH
4.0
VDD +
V
Input leakage
current
IXTALI
Operational
power supply
current
ICC
L-input voltage
H-input voltage
MODE,
SYNC
0.4
Input leakage
current
1)
ILI1
ILI2
ILI3
ILI4
µA
µA
µA
µA
800
100
800
200
VIL = 0.8 V
VIL = 0.1 V
VIH = 4 V
VIH = VDD
Measured against VDD2
4.4
Characteristics
TA = 25 °C; VDD = 5 V ± 5 %, VSS = 0 V
Parameter
Symbol
Limit Values
min.
Unit
Pins
max.
Input capacitance
CIN
10
pF
all except RLx, XLx,
XTALx
Output capacitance
COUT
15
pF
all except RLx, XLx,
XTALx
Input capacitance
CIN
COUT
7
pF
RLx
20
pF
XLx
Output capacitance
Semiconductor Group
30
PEB 22320
Electrical Specification
4.5
Recommended Oscillator Circuits
XTAL1
(XTAL3)
C L = 14 pF (4 pF)
16.384 MHz
(12.352 MHz)
PRACT
XTAL1
(XTAL3)
PRACT
XTAL2
(XTAL4)
XTAL2
(XTAL4)
External
Oscillator
Signal
16.384 MHz
(12.352 MHz)
N.C.
14 pF
Crystal Oscillator mode
(slave mode/ master mode)
Driving from external source
(master mode)
ITS04888
Figure 16
Oscillator Circuits
In CEPT mode if an external source is connected to XTAL1, the PRACT works,
independent of the MODE pin, in master mode.
In T1 mode if an external source is connected to XTAL3, the PRACT works, independent
of the MODE pin, in master mode. This operational mode requires a crystal
(16.384 MHz) at pins XTAL1 and XTAL2. The frequency is locked to the external source.
The jitter attenuator requires unique performance specifications for the crystals.
The following typical crystal parameters will meet this specifications:
– Motional capacitance
– Shunt capacitance
– Load capacitance
– Resonance resistance
Semiconductor Group
C1 = 25 fF min
C0 = 7 pF max
CL = 18 pF typ, f0 = 16.384 MHz
CL = 10 pF typ, f0 = 12.352 MHz
Rr ≤ 25 Ω
31
PEB 22320
Electrical Specification
PRACT Tuning Range 16.384 MHz PLL
Crystal specified for CL = 18 pF
ITD06578
150
d f ppm
f 0 100
50
0
-50
-100
-150
14
16
18
20
22
24
pF
CL
Figure 17
16.384-MHz Crystal Tuning Range
Semiconductor Group
32
26
PEB 22320
Electrical Specification
PRACT Tuning Range 12.352 MHz PLL
Crystal specified for CL = 10 pF
ITD06579
250
ppm
d f 200
f0
150
100
50
0
-50
-100
-150
-200
-250
6
8
10
12
14
16
pF
CL
Figure 18
12.352-MHz Crystal Tuning Range
Semiconductor Group
33
18
PEB 22320
Electrical Specification
4.6
AC Characteristics
TA = 0 to 70 °C; VDD = 5 V ± 5 %
2.4
2.0
2.0
Device
Under
Test
Test Points
0.8
0.8
C Load = 150 pF
0.45
ITS00621
Figure 19
Input/Output Waveforms for AC Tests
Except from the line interface, inputs are driven at 2.4 V for a logical 1 and 0.4 V for a
logical 0. Timing measurements are made at 2.0 V for a logical 1 and at 0.8 V for a logical
0. AC testing input/output waveforms are shown in figure 19.
4.6.1
Dual Rail Interface
RDOP, RDON, XDIP, XDIN, XTIP, XTIN are active low.
t CPR
t CPRH
t CPRL
RCLK
t DROS
t DROH
RDOP, RDON
t CPX
t CPXH
t CPXL
XCLK
t DRIS
t DRIH
XDIP, XDIN
XTIP, XTIN
ITT04889
Figure 20
Timing of the Dual Rail Interface
Semiconductor Group
34
PEB 22320
Electrical Specification
Parameter
Symbol
Limit Values
PCM 30
min.
max.
Unit
PCM 24
min.
max.
RCLK clock period
tCPR
RCLK clock period low
tCPRL
200
260
ns
RCLK clock period high
tCPRH
200
260
ns
Dual rail output setup
tDROS
200
260
ns
Dual rail output hold
tDROH
200
260
ns
XCLK clock period
tCPX
XCLK clock period low
tCPXL
200
250
ns
XCLK clock period high
tCPXH
200
250
ns
Dual rail input setup
tDRIS
25
25
ns
Dual rail input hold
tDRIH
25
25
ns
Semiconductor Group
typ. 488
typ. 648
typ. 488
35
typ. 648
ns
ns
PEB 22320
Electrical Specification
4.6.2
System Clock Interface
t CP16L
t CP16
t CP16H
CLK16M
t CP4L
t CP4
t CP4H
CLK4M
CLK4M
t CP2
t CP2L
t CP2H
CLK2M
CLK2M
t SS
t SH
FSC
FSC
t CP12L
t CP12
t CP12H
CLK12M
t CP15
t CP15L
t CP15H
XCLK (T1)
ITT04890
Figure 21
Timing of the System Clock Interface
Semiconductor Group
36
PEB 22320
Electrical Specification
System Clock Interface Timing Parameter Values
Parameter
Symbol
Limit Values
min.
CLK16M period 16 MHz
CLK16M period 16 MHz low
CLK16M period 16 MHz high
CLK4M period 4 MHz
CLK4M period 4 MHz low
CLK4M period 4 MHz high
CLK2M period 2 MHz
CLK2M period 2 MHz low
CLK2M period 2 MHz high
FSC setup time
FSC hold time
CLK12M period 12 MHz
CLK12M period 12 MHz low
CLK12M period 12 MHz high
XCLK period 1.5 MHz
XCLK period 1.5 MHz low
XCLK period 1.5 MHz high
Semiconductor Group
tCP16
tCP16L
tCP16H
tCP4
tCP4L
tCP4H
tCP2
tCP2L
tCP2H
tSS
tSH
tCP12
tCP12L
tCP12H
tCP15
tCP15 L
tCP15 H
37
Unit
max.
typ. 61
ns
20
ns
20
ns
typ. 244
ns
110
ns
110
ns
typ. 488
ns
220
ns
220
ns
110
ns
240
ns
typ. 81
ns
30
ns
30
ns
typ. 648
ns
300
ns
300
ns
PEB 22320
Electrical Specification
4.6.3
Microprocessor Interface
t CYC
t WC
CS
t DW
t WD
DATA
(JATT, RL, LL, LS0, 1, 2)
ITT04891
Figure 22
Timing of the Microprocessor Interface
Parameter
CS pulse width
Data setup time to CS
Data hold time from CS
Cycle time
Semiconductor Group
Symbol
tWC
tDW
tWD
tCYC
Limit Values
min.
max.
60
–
ns
35
–
ns
10
–
ns
120
38
Unit
ns
PEB 22320
Electrical Specification
4.6.4
XTAL Timing
tP
t WH
XTAL1
XTAL3
t WL
3.5 V
0.8 V
ITT04892
Figure 23
Timing of XTAL1/XTAL3
XTAL1/XTAL3 Timing Parameter Values
Parameter
Symbol
Limit Values
min.
typ.
Unit
Condition
ns
XTAL1
XTAL3
max.
Clock period of crystal/
clock
tP
High phase crystal/clock
tWH
20
30
ns
XTAL1
XTAL3
Low phase of crystal/clock tWL
20
30
ns
XTAL1
XTAL3
61
81
Note: If an external clock is used the PRACT works as a master. Please refer to Pin
Definitions.
Semiconductor Group
39
PEB 22320
Electrical Specification
4.7
Pulse Templates - Transmitter
The PRACT meets both CCITT and T1 pulse template requirements.
269 ns
(244 + 25)
V=100 %
10 % 10 %
20 %
20 %
194 ns
(244 - 50)
Nominal Pulse
50 %
244 ns
10 % 10 %
20 %
0%
10 % 10 %
219 ns
(244 - 25)
488 ns
(244 + 244)
ITD00573
Figure 24
Pulse Template at the Transmitter Output for CEPT Applications
Semiconductor Group
40
PEB 22320
Electrical Specification
Normalized Amplitude
V = 100 %
50 %
0
-50 %
0
250
500
750
1000
ns
ITD00574
Figure 25
T1 Pulse Shape at the Cross Connect Point
Table 8
T1 Pulse Template Corner Points at the Cross Connect Point
Maximum Curve
Minimum Curve
(0
0.05)
(0,
– 0.05
(250,
0.05)
(350,
– 0.05)
(325,
0.80)
(350,
– 0.50)
(325,
1.15)
(400,
0.95)
(425,
1.15)
(500,
0.95)
(500,
1.05)
(600,
0.90)
(675,
1.05)
(650,
0.50)
(725,
– 0.07)
(650,
– 0.45)
(1100,
0.05)
(800,
– 0.45)
(1250,
0.05)
(925,
– 0.20)
(1100,
– 0.05)
(1250,
– 0.05)
Semiconductor Group
41
t
PEB 22320
Electrical Specification
3.0
0.7 0.7
V
50 ns
50 ns
1.5
1.2
0.3
0
-
3T
T
8
4
0
T
8
T
4
3T
8
T
2
T = 1/1544
kHz
ITD00575
Figure 26
Pulse Shape According to CCITT G.703
4.8
Overvoltage Tolerance
To prevent the PRACT from being damaged by overvoltage (i.e. from lightning), external
devices like diodes or resistors have to be connected to one or both sides of the line
interface transformers. Thus, overvoltage peaks are cut off. However, some residual
overvoltage may remain.
The PRACT simplifies the task of designing external protection circuits. Its transmitter
exhibits a low line impedance so that reasonable external resistors can be connected to
the line outputs. Figure 8 with the element values of table 7 gives an example of how an
overvoltage protection against residual overvoltages at the ternary interface can be
accomplished. The solution shown also meets the stated return loss requirements.
A similar consideration applies to the receiver. The resistors R2 of figure 3 provide
protection against residual overvoltages by attenuating voltages of both polarities across
RL1 and RL2.
The maximum input current allowed to reach the PRACT pins under overvoltage
conditions is given as a function of the width of a rectangular input current pulse
according to figure 27. Figure 29 shows the curve of the maximum allowed input current
across the pins RL1 and RL2, figure 28 across the pins XL1 and XL2.
Semiconductor Group
42
PEB 22320
Electrical Specification
Ι
FALC TM -54
Ιp
t
t WI
ITS04893
Condition: All other pins grounded
Figure 27
Measurement of Overvoltage Stress
ΙP
A
100
50
10 dB/Decade
R i <_ 2 Ω
10
5
1
0.5
2x10 -1
10 -9
10 -6
10 -3 10 -2 1
t WI
s
ITD00578
Figure 28
Tolerated Input Current at the XL1, XL2 Pins
Semiconductor Group
43
PEB 22320
Electrical Specification
ΙP
A
20
10
10 dB/Decade
R i <_ 300 Ω
1
6x10
-1
10 -1
2x10 -1
10 -10 10 -9
10 -6
10 -4 10 -3
t WI
s
1
ITD00577
Figure 29
Tolerated Input Current at the RL1, RL2 Pins
Semiconductor Group
44
PEB 22320
Package Outlines
5
Package Outlines
GPL05102
Plastic Package, P-LCC-44 (SMD)
(Plastic Leaded Chip Carrier)
Sorts of Packing
Package outlines for tubes, trays etc. are contained in our
Data Book “Package Information”.
SMD = Surface Mounted Device
Semiconductor Group
45
Dimensions in mm