XRT79L72 Datasheet, PDF(34/72 Page) Exar Corporation – 2

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XRT79L72 Datasheet, PDF (34/72 Pages) Exar Corporation – 2 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

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XRT79L72

REV. P1.0.2

PIN #

J25

NAME

RxPFrame_0/

RxOHInd_0

RxPFrame_1/

RxOHInd_1

PRELIMINARY

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

TYPE

DESCRIPTION

Receive PLCP Frame Indicator/Receive Overhead Indicator Output:

The function of these output pins depend upon whether the XRT79L72 has

been configured to operate in the ATM/PLCP, the Clear-Channel Framer/Serial

or the Clear-Channel Framer/Nibble-Parallel Modes.

ATM/PLCP Mode - RxPFrame:

These output pins pulse "High" when the Receive PLCP Processor is receiving

the last bit of a PLCP frame.

NOTE: These output pins are inactive if the XRT79L72 is configured to operate

in the Direct-Mapped ATM Mode.

Clear-Channel Framer/Serial Mode - RxOHInd:

These output pins pulse "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.

NOTE: If the user configures the XRT79L72 to operate in the Gapped-Clock

Mode, then these output pins will provide a demand clock to the local terminal

equipment. In the Gapped-Clock Mode, these output pins will only provide a

clock pulse, whenever a payload bit is being output via the RxSer output pin.

These output pins will NOT generate a clock pulse, whenever an overhead is

being output via the RxSer output pin.

Clear-Channel Framer/Nibble-Parallel - RxOHInd:

These output pins pulse "High" for one nibble-period whenever an overhead

nibble is being output via the RxNibn[3:0] output pins by the Receive Payload

Data Output Interface block.

NOTE: 1.If the XRT79L72 device has been configured to operate in both the

DS3 and the Nibble-Parallel" Modes, then the RxOHInd output pin will be in-

active and will pulled "LOW" at all times.

NOTE: 2.If the XRT79L72 device has been configured to operate in both the E3

and the Nibble-Parallel" Mode, then the RxOHInd output pin will be active and

will pulse "high" to denote overhead nibbles.

NOTE: 3.The purpose of this output pin is to alert the System-Side terminal

equipment that an

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