CS61574A/75 Cirrus Logic, Inc., CS61574A/75 Datasheet - Page 28

• Manufacturer Part Number: CS61574A/75
• Description: T1/E1 Line Interface Unit for Stratum-4 applications
• Manufacturer: Cirrus Logic, Inc.

APPLICATIONS
Line Interface
Figures A1-A3 show typical T1 and E1 line inter-
face 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
interface in the Hardware Mode. Figure A3 illus-
trates a 75
Hardware Mode
The receiver transformer has a grounded center
tap on the IC side. Resistors between the RTIP
28
E1 interface in the Extended
Encoder/
Decoder
Monitor
Control
Format
Frame
&
XTL
Frequency
1.544 (T1)
2.048 (E1)
MHz
RV+
+
28
12
11
10
1
5
7
6
8
3
4
2
9
68 F
RGND
CLKE
ACLKI
LOS
DPM
MODE
RPOS
RNEG
RCLK
TPOS
TNEG
TCLK
XTALIN
XTALOUT
Figure A1. T1 Host Mode Configuration
Table A1. External Component Values
Cable
100
120
75
0.1 F
CS61574A
RGND
CS61575
+5V
RV+
MODE
HOST
OR
21
IN
22
E1
R1 and R2
TV+
TGND
200
240
150
15
14
MRING
RRING
TRING
and RRING pins to ground provide the termina-
tion for the receive line.
The transmitter transformer matches the 75
transmitter output impedance to the line imped-
ance. Figures A1-A3 show a 0.47 F capacitor 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 satu-
rate the transformer producing an output offset
level shift.
SCLK
MTIP
RTIP
+
SDO
TTIP
SDI
INT
CS
1.0 F
TGND
Transformer
Transmit
27
26
23
24
25
19
20
17
18
16
13
1:1.15
1:1.26
1:1
+5V
0.47 F
100 k
R1
R2
Serial
Port
1
3
5
2
6
CXT6176
CXT8192
PE-65351
PE-65388
P
Crystal
1:1.15
2CT:1
XTL
2
6
1
5
CS61574A CS61575
RECEIVE
LINE
TRANSMIT
LINE
DS154F2