CS61577-IL1Z データシートの表示（PDF） - Cirrus Logic

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CS61577-IL1Z

T1/E1 Line Interface

Cirrus Logic 

CS61577

#3

Simultaneous selection of local and remote loop-

back modes is not valid (see Reset).

In the Extended Hardware Mode the transmitted

data is looped before the AMI/B8ZS/HDB3 en-

coder/decoder during remote loopback so that the

transmitted signal matches the received signal,

even in the presence of received bipolar viola-

tions. Data output on RDATA is decoded,

however, if RCODE is low.

Alarm Indication Signal

In the Extended Hardware Mode, the receiver sets

the output pin AIS high when less than 3 zeros

are detected out of 2048 bit periods.

Line Code Encoder/Decoder

In the Extended Hardware Mode, three line codes

are available: AMI, B8ZS and HDB3. The input

to the encoder is TDATA. The outputs from the

decoder are RDATA and BPV (Bipolar Violation

Strobe). The encoder and decoder are selected

using the LEN2, LEN1, LEN0, TCODE and

RCODE pins as shown in Table 8.

TCODE

(Transmit

Encoder

Selection)

RCODE

(Receiver

Decoder

Selection)

LOW

HIGH

LOW

HIGH

LEN 2/1/0

000

010-111

HDB3

Encoder

B8ZS

Encoder

AMI Encoder

HDB3

Decoder

B8ZS

Decoder

AMI Decoder

Table 8. Encoder/Decoder Selection

Parallel Chip Select

In the 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 and will immediately change

the operating state of the device. Therefore, when

cycling PCS to update the operating state, the

digital control inputs should be stable for the en-

tire PCS low period. The digital control inputs are

ignored when PCS is high

Driver Performance Monitor

To aid in early detection and easy isolation of

non-functioning links, the IC is 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 low, and goes high upon detecting a driver

failure.

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. In the Host Mode,

DPM is available from the register and pin 11.

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 IC, rather than having it monitor its own

performance. Note that a CS61577 can not be

used to monitor a CS61574 due to output stage

differences.

$D3S1550F0

15

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