XRT79L71IB datasheet(22/441 Pages) EXAR

22 / 441 page

XRT79L71

PRELIMINARY

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REV. P1.0.3

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

C11

TxOH/

TxHDLCDat_5

Transmit Overhead Data Input/Transmit HDLC Controller Data Bit 5 input

pin:

The function of This input pin depends upon whether or not the XRT79L71 has

been configured to operate in the High-Speed HDLC Controller Mode.

Non-High Speed HDLC Controller Mode - TxOH:

The Transmit Overhead Data Input Interface accepts overhead via this input pin,

and insert this data into the overhead bit positions within the outbound DS3 or E3

frames. If the TxOHIns input pin is pulled "High", then the Transmit Overhead

Data Input Interface will sample the overhead data, via this input pin, upon the

falling edge of the TxOHClk output signal.

Conversely, if the TxOHIns input pin is NOT pulled "High", then the Transmit

Overhead Data Input Interface block will be inactive and will not accept any over-

head data via the TxOH input pin.

High Speed HDLC Controller Mode - TxHDLCDat_5:

If the XRT79L71 is configured to operate in the High-Speed HDLC Controller

mode, then the local terminal equipment will be provided with a byte-wide Trans-

mit HDLC Controller byte-wide input interface. This input pin will function as Bit 5

within this byte wide interface.

Data, residing on the Transmit HDLC Controller byte wide input interface, will be

sampled upon the rising edge of the TxHDLCClk output signal.

D10

TxOHIns/

TxHDLCDat_4

Transmit Overhead Data Insert Input/Transmit HDLC Controller Data Bit 4

input pin:

The function of this input pin depends upon whether or not the XRT79L71 has

been configured to operate in the High-Speed HDLC Controller Mode.

Non-High Speed HDLC Controller Mode - TxOHIns:

This input pin is used to either enable or disable the Transmit Overhead Data

Input Interface block. If the Transmit Overhead Data Input Interface block is

enabled, then it will accept overhead data from the local terminal equipment via

the TxOH input pin; and insert this data into the overhead bit positions within the

outbound DS3 or E3 data stream.

Conversely, if the Transmit Overhead Data Input Interface block is disabled, then

it will NOT accept overhead data from the local terminal equipment.Pulling this

input pin "High" enables the Transmit Overhead Data Input Interface block. Pull-

ing this input pin "Low" disables the Transmit Overhead Data Input Interface

block.

High-Speed HDLC Controller Mode - TxHDLCDat_4:

If the XRT79L71 is configured to operate in the High-Speed HDLC Controller

mode, then the local terminal equipment will be provided with a byte-wide Trans-

mit HDLC Controller byte-wide input interface. This input pin will function as Bit 4

within this byte wide interface.

Data, residing on the Transmit HDLC Controller byte wide input interface, will be

sampled upon the rising edge of the TxHDLCClk output signal.

B12

TxOHClk

Transmit Overhead Clock Output:

This output pin functions as the Transmit Overhead Data Input Interface clock

signal. If the user enables the Transmit Overhead Data Input Interface block by

asserting the TxOHIns input pin, then the Transmit Overhead Data Input Inter-

face block will sample and latch the data residing on the TxOH input pin upon the

falling edge of this signal.

NOTE: The Transmit Overhead Data Input Interface block is disabled if the user

has configured the XRT79L71 to operate in the High-Speed HDLC

Controller Mode.

PIN #NAME

TYPE

DESCRIPTION

XRT79L71IB Datasheet(PDF) 22 Page - Exar Corporation

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