CY74FCT652T

8-BIT REGISTERED TRANSCEIVER

WITH 3-STATE OUTPUTS

SCCS032B – SEPTEMBER 1994 – REVISED OCTOBER 2001

1

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

D Function, Pinout, and Drive Compatible

With FCT and F Logic

D Reduced VOH (Typically = 3.3 V) Version of

Equivalent FCT Functions

D Edge-Rate Control Circuitry for

Significantly Improved Noise

Characteristics

D Ioff Supports Partial-Power-Down Mode

Operation

D Matched Rise and Fall Times

D Fully Compatible With TTL Input and

Output Logic Levels

D 64-mA Output Sink Current

32-mA Output Source Current

D Independent Register for A and B Buses

D Multiplexed Real-Time and Stored Data

Transfer

D 3-State Outputs

description

The CY74FCT652T consists of bus transceiver circuits, D-type flip-flops, and control circuitry arranged for

multiplexed transmission of data directly from the input bus or from the internal storage registers. GAB and GBA

inputs control the transceiver functions. Select-control (SAB and SBA) inputs select either real-time or

stored-data transfer. The circuitry used for select control eliminates the typical decoding glitch that occurs in

a multiplexer during the transition between stored and real-time data. A low input level selects real-time data,

and a high input level selects stored data.

Data on the A or B data bus, or both, can be stored in the internal D-type flip-flops by low-to-high transitions

of the appropriate clock (CPAB or CPBA) inputs, regardless of the select or enable levels of the control pins.

When SAB and SBA are in the real-time transfer mode, it also is possible to store data without using the internal

D-type flip-flops by simultaneously enabling GAB and GBA. In this configuration, each output reinforces its

input. Thus, when all other data sources to the two sets of bus lines are at high impedance, each set of bus

lines remains at its last state.

This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs,

preventing damaging current backflow through the device when it is powered down.

Copyright

 2001, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

Q OR SO PACKAGE

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CPAB

SAB

GAB

A1

A2

A3

A4

A5

A6

A7

A8

GND

VCC

CPBA

SBA

GBA

B1

B2

B3

B4

B5

B6

B7

B8