XRT59L91 データシートの表示（PDF） - Exar Corporation

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XRT59L91

Single-Chip E1 Line Interface Unit

Exar Corporation 

XRT59L91

Preliminary

PIN DESCRIPTION

Pin#

3

4

5

Symbol

TxNEG

LLoop

RLoop

Type

I

I

I

Description

Transmit – Negative Data Input:

The exact signal that should be applied to this input pin depends

upon whether the user intends to operate the “Transmit Section” (of

the device) in the “Clocked” or “Clockless” Mode.

Clocked Mode -

The Terminal Equipment should apply bit-wide NRZ pulses on this

input pin, whenever the Terminal Equipment needs to transmit a

“negative-polarity” pulse onto the line via TTIP and TRing output

pins. The XRT59L91 device will sample this input pin upon the

falling edge of the TClk signal.

Clockless Mode -

The Terminal Equipment should apply RZ pulses to this input pin,

anytime the Terminal Equipment needs to transmit a “negative-

polarity” pulse onto the line via TTIP and TRing output pins.

Local Loopback Input Select:

This input pin permits the user to configure the XRT59L91 device to

operate in the “Local Loopback” Mode; in order to support Diagnostic

Operations.

When the XRT59L91 device is operating in the Local Loopback

Mode, then TTIP and TRing output signals will be (internally)

routed to RTIP and RRing input signals.

Setting this input pin “high” configures the XRT59L91 device to

operate in the “Local Loopback” Mode. Setting this input pin “low”

configures the XRT59L91 device to operate in the “Normal” Mode.

Note: Pulling both the “LLoop” and “RLoop” input pins to VDD,

simultaneously, will cause the XRT59L91 device to operate in the “In-

Circuit Test” Mode. In this mode, all output pins will be tri-stated.

Remote Loopback Input Select:

This input pin permits the user to configure the XRT59L91 device to

operate in the “Remote Loopback” Mode; in order to support Diagnos-

tic Operations.

When the XRT59L91 device is operating in the Remote Loopback

Mode, then the RxPOS and RxNEG output pins will be (internally)

routed to the TxPOS and TxNEG input pins.

Setting this input pin “high” configures the XRT59L91 device to

operate in the “Remote Loopback” Mode. Setting this input pin “low”

configures the XRT59L91 device to operate in the “Normal” Mode.

Note: Pulling both the “LLoop” and “RLoop” input pins to VDD,

simultaneously, will cause the XRT59L91 device to operate in the “In-

Circuit Test” Mode. In this mode, all output pins will be tri-stated.

Rev. P2.00

4

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