XRT7250 datasheet(36/463 Pages) EXAR

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DS3/E3 FRAMER IC

XRT7250

REV. 1.1.1

RxOHInd

Receive Overhead Bit Indicator

The exact functionality of this output pin depends upon whether the XRT7250

Framer IC is operating in the “Serial” or “Nibble-Parallel” Mode.

Serial Mode Operation:

This output pin pulses "high" (for one bit-period) whenever an "overhead" bit is

being output via the "RxSer" output pin, by the "Receive Payload Data Output

Interface" block.

Nibble-Parallel Mode Operation:

This output pin pulses “high” (for one nibble-period) whenever an “overhead”

nibble is being output via the “RxNib[3:0] output pins, by the “Receive Payload

Data Output Interface” block.

NOTE: The purpose of this output pin is to alert the "Receive Terminal Equip-

ment" that an overhead bit is being output via the "RxSer" output pin, and that

this data should be ignored.

RxOH

Receive Overhead Output Port

All overhead bits, which are received via the "Receive Section" of the Framer

IC; will be output via this output pin, upon the rising edge of RxOHClk.

RxOHEnable

Receive Overhead Enable Indicator

The XRT7250 will assert this output signal for one “RxOutClk” period when it is

safe for the Terminal Equipment to sample the data on the “RxOH” output pin.

100

RxOHFrame

Receive Overhead Frame Boundary Indicator

This output pin pulses "high" whenever the Receive Overhead Data Output

Interface” block outputs the first overhead bit (or nibble) of a new DS3 or E3

frame.

PIN DESCRIPTION

PIN #NAME

TYPE

DESCRIPTION

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