XRT79L71IB datasheet(16/441 Pages) EXAR

16 / 441 page

XRT79L71

PRELIMINARY

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REV. P1.0.3

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

PIN DESCRIPTIONS

PIN #NAME

TYPE

DESCRIPTION

MICROPROCESSOR INTERFACE

F16

F15

F14

F13

G16

G15

G14

G13

C16

D15

D16

E16

E15

E14

E13

A10

A11

A12

A13

A14

Address Bus Input pins Microprocessor Interface:

These pins are used to select the on-chip Framer/UNI registers and RAM space for

READ and WRITE Operations with the Microprocessor.

D11

C12

B13

A14

D12

C13

B14

A15

I/O

Bi-Directional Data Bus pins Microprocessor Interface:

These pins are used to drive and receive data over the bi-directional data bus.

A16

ALE/AS

Address Latch Enable/Address Strobe:

This input pin is used to latch the address present at the Microprocessor Interface

Address Bus pins (A[6:0]) into the Framer/UNI Microprocessor Interface block and to

indicate the start of a READ or WRITE cycle. This input pin is active-high, in the Intel

Mode and active low in the Motorola Mode.

D14

Chip Select Input:

The user must assert this active low signal in order to select the Microprocessor

Interface for READ and WRITE operations between the Microprocessor and the UNI/

Framer on-chip registers and RAM locations.

D13

INT

Interrupt Request Output:

This open-drain, active-low output signal will be asserted when the Framer/UNI

device is requesting interrupt service from the Microprocessor. This output pin

should typically be connected to the Interrupt Request input of the Microprocessor.

C15

RD/DS/I

READ Strobe Intel Mode:

If the Microprocessor Interface is operating in the Intel Mode, then this input pin will

function as the RD (READ Strobe) input signal from the Microprocessor. Once this

active-low signal is asserted, then the Framer/UNI will place the contents of the

addressed register within the Framer/UNI IC on the Microprocessor Bi-directional

Data Bus (D[7:0]). When this signal is negated, the Data Bus will be tri-stated.

Data Strobe Motorola Mode:

If the Microprocessor Interface is operating in the Motorola Mode, then this input will

function as the DS (Data Strobe) signal.

XRT79L71IB Datasheet(PDF) 16 Page - Exar Corporation

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