CS61535A datasheet(17/48 Pages) CIRRUS

17 / 48 page

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.

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 a nd

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-

LEN 2/1/0

000

010-111

TCODE

(Transmit

Encoder

Selection)

LOW

HDB3

Encoder

B8ZS

Encoder

HIGH

AMI

Encoder

RCODE

(Receiver

Decoder

Selection)

LOW

HDB3

Decoder

B8ZS

Decoder

HIGH

AMI

Decoder

Table 6. Selection of Encoder/Decoder

CS61535A

DS40F2

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