CS61535A Cirrus Logic, Inc., CS61535A Datasheet - Page 17

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

RDATA). Remote loopback is selected by taking
pin 26 high, or RLOOP may be selected using the
serial interface. Simultaneous selection of local
and remote loopback modes is not valid (see Re-
set).
In the CS61535A Extended Hardware Mode, re-
mote loopback occurs before the line code
encoder/decoder, insuring that the transmitted sig-
nal matches the received signal, even in the
presence of received bipolar violations. The re-
covered data will also be decoded and output on
RDATA if RCODE is low.
Driver Performance Monitor
To aid in early detection and easy isolation of
nonfunctioning links, the Hardware and Host
Modes of the CS61535A are 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 perform-
ance or the performance of a neighboring driver.
The driver performance monitor indicator is nor-
mally at a low (zero) logic level, and goes to high
level upon detecting driver failure. In the Host
Mode, DPM is available from both the register
and pin 11.
The driver performance monitor consists of an ac-
tivity 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.
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 neigh-
boring device, rather than having it monitor its
own performance.
DS40F2
Line Code Encoder/Decoder
In Extended Hardware Mode, three line codes are
available: AMI, B8ZS and HDB3. The input to
the encoder is TDATA. The outputs from the de-
coder are RDATA and BPV (Bipolar Violation
Strobe). The encoder and decoder are selected us-
ing pins LEN2, LEN1, LEN0, TCODE and
RCODE as shown in Table 6.
Alarm Indication Signal
In Extended Hardware Mode, the receiver sets the
output pin AIS high when less than 9 zeros are
detected out of 8192 bit periods. AIS returns low
when 9 or more zeros are detected out of 8192
bits.
Parallel Chip Select
In 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. Changes in inputs will immedi-
ately change the operating state of the device.
Therefore, when cycling PCS to update the oper-
ating state, the digital control inputs should be
stable for the entire PCS low period. The control
inputs are ignored when PCS is high.
Power On Reset / Reset
Upon power-up, the CS61535A is held in a static
state until the supply crosses a threshold of ap-
Selection)
Selection)
(Receiver
(Transmit
Decoder
Encoder
RCODE
TCODE
Table 6. Selection of Encoder/Decoder
HIGH
HIGH
LOW
LOW
Decoder
Encoder
HDB3
HDB3
000
LEN 2/1/0
Encoder
Decoder
AMI
AMI
CS61535A
Decoder
Encoder
010-111
B8ZS
B8ZS
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