XRT79L71IB datasheet(40/441 Pages) EXAR

40 / 441 page

XRT79L71

PRELIMINARY

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REV. P1.0.3

1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

RxPOH/

RxSer

Receive PLCP Path Overhead Output pin/Receive Serial Output pin:

The function of this output depends upon whether the XRT79L71 has been con-

figured to operate in the ATM/PLCP Mode or in the Clear-Channel Framer

Mode.

ATM/PLCP Mode - RxPOH:

This output pin along with the RxPOHClk, RxPOHFrame and RxPOHIns pins

comprise the Receive PLCP Frame POH Byte serial output port. For each

PLCP frame, that is received by the Receive PLCP Processor, this serial output

port will output the contents of all 12 POH (Path Overhead) bytes. The data that

is output via this pin, is updated on the rising edge of the RxPOHClk output

clock signal. The RxPOHFrame pin will pulse "High" whenever the first bit of the

Z6 byte is being output via this output pin.

Clear-Channel Framer Mode - RxSer:

If the XRT79L71 is configured to operate in the Clear-Channel Framer/Serial

Mode, then the chip will output all received data, via this output pin. This output

signal will be updated upon the rising edge of RxClk.

NOTE:

The user should either configure the XRT79L71 to operate in the

Gapped-Clock Mode, or validate the sampling of each bit from the

RxSer output with the state of RxOHInd' output pin, in order to prevent

the local terminal equipment from sampling overhead bits.

This output pin is only active if the XRT79L71 has been configured to operate in

the ATM/PLCP or the Clear-Channel Framer/Serial Mode. This pin is inactive

for all remaining modes of operation.

PIN #NAME

TYPE

DESCRIPTION

XRT79L71IB Datasheet(PDF) 40 Page - Exar Corporation