CS61535A Cirrus Logic, Inc., CS61535A Datasheet - Page 29

• Manufacturer Part Number: CS61535A
• Description: T1-E1 Line Interface Unit for PCM applications
• Manufacturer: Cirrus Logic, Inc.

APPLICATIONS
Line Interface
Figures A1-A3 show the typical configurations
for interfacing the I.C. to a line through transmit
and receive transformers.
The receiver transformer is center tapped and
center grounded with resistors between the center
tap and each leg on the I.C. side. These resistors
provide the termination for the line.
Figures A1-A3 show a 0.47 F capacitor in series
with the transmit transformer primary. This ca-
pacitor is needed to prevent any buildup in the
DS40F2
Encoder/
Decoder
Monitor
Control
Format
Frame
&
XTL
CS61535A
DEVICE
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
FREQUENCY
Figure A1. Host Mode Configuration
0.1 F
1.544
2.048
2.048
MHz
CS61535A
RGND
+5V
RV+
MODE
HOST
21
IN
22
TV+
TGND
15
14
MRING
RRING
TRING
CABLE
SCLK
MTIP
RTIP
core of the transformer due to any DC imbalance
that may be present at the differential outputs,
TTIP and TRING. If DC saturates the trans-
former, a DC offset will result during the
transmission of a space (zero) as the transformer
tries to dump the charge and return to equilib-
rium. The blocking capacitor will keep DC
current from flowing in the transformer.
Selecting an Oscillator Crystal
Specific crystal parameters are required for
proper operation of the CS61535A. It is recom-
mended that the CXT6176 from Crystal
+
SDO
TTIP
100
120
SDI
75
INT
CS
1.0 F
TGND
27
26
23
24
25
19
20
17
18
16
13
+5V
0.47 F
100 k
R1
R2
R1&2
200
240
150
Serial
Port
P
CT 2:1
Transformer
Transmit
RECEIVE
LINE
1:1.15
1:1.26
1:1
TRANSMIT
LINE
CS61535A
29