CS61577
THEORY OF OPERATION
CS61577 Enhancements Relative to CS61574
Existing designs using the CS61574 can be con-
verted 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:
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Selection of 75
Ω
or 120
Ω
E1 output op-
tions under
software
or hardware control,
50 mA
RMS
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 re-
flections for improved signal quality,
Optional AMI, B8ZS, HDB3 encoder/de-
coder 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.
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 thir-
teen multi-function pins whose functionality is
determined by the operating mode. (see Table 2).
Hardware
Mode
Control
Method
MODE
Pin
Level
Line
Coding
AIS
Detection
Driver
Performance
Monitor
Control
Pins
<0.2 V
Extended
Host
Hardware
Mode
Mode
Control Pins
Serial
with Parallel
Interface
Chip Select
Floating or >(RV+)-0.2 V
2.5 V
Internal-
AMI, B8ZS,
or HDB3
Yes
No
External
External
No
Yes
No
Yes
Table 1. Differences Between Operating Modes
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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 Hard-
ware Mode, and Host Mode. In Hardware and
Extended Hardware Modes, discrete pins are used
to configure and monitor the device. The Ex-
tended Hardware Mode provides a parallel chip
select input which latches the control inputs al-
8
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
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