CY54FCT646T, CY74FCT646T

8-BIT REGISTERED TRANSCEIVERS

WITH 3-STATE OUTPUTS

SCCS031A – JULY 1994 – REVISED OCTOBER 2001

2

POST OFFICE BOX 655303

PIN DESCRIPTION

NAME

DESCRIPTION

A

Data register A inputs, data register B outputs

B

Data register B inputs, data register A outputs

CPAB, CPBA

Clock-pulse inputs

SAB, SBA

Output data-source-select inputs

DIR, G

Output-enable inputs

ORDERING INFORMATION

TA

PACKAGE†

SPEED

(ns)

ORDERABLE

PART NUMBER

TOP-SIDE

MARKING

QSOP – Q

Tape and reel

5.4

CY74FCT646CTQCT

FCT646C

SOIC

SO

Tube

5.4

CY74FCT646CTSOC

FCT646C

SOIC – SO

Tape and reel

5.4

CY74FCT646CTSOCT

FCT646C

QSOP – Q

Tape and reel

6.3

CY74FCT646ATQCT

FCT646A

–40

°C to 85°C

SOIC

SO

Tube

6.3

CY74FCT646ATSOC

FCT646A

SOIC – SO

Tape and reel

6.3

CY74FCT646ATSOCT

FCT646A

QSOP – Q

Tape and reel

9

CY74FCT646TQCT

FCT646

SOIC

SO

Tube

9

CY74FCT646TSOC

FCT646

SOIC – SO

Tape and reel

9

CY74FCT646TSOCT

FCT646

LCC – L

Tube

6

CY54FCT646CTLMB

55

°Cto125°C

CDIP – D

Tube

7.7

CY54FCT646ATDMB

–55

°C to 125°C

LCC

L

Tube

7.7

CY54FCT646ATLMB

LCC – L

Tube

11

CY54FCT646TLMB

† Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are

available at www.ti.com/sc/package.

FUNCTION TABLE

INPUTS

DATA I/O‡

OPERATION

G

DIR

CPAB

CPBA

SAB

SBA

A1–A8

B1–B8

OR FUNCTION

H

X

H or L

H or L

X

X

Input

Input

Isolation

H

X

↑↑

X

X

Input

Input

Store A and B data

L

L

X

X

X

L

Output

Input

Real-time B data to A bus

L

L

X

H or L

X

H

Output

Input

Stored B data to A bus

L

H

X

X

L

X

Input

Output

Real-time A data to B bus

L

H

H or L

X

H

X

Input

Output

Stored A data to B bus

H = High logic level, L = Low logic level,

↑ = Low-to-high transition, X = Don’t care

‡ The data output functions can be enabled or disabled by various signals at the G or DIR inputs. Data input

functions always are enabled, i.e., data at the bus pins is stored on every low-to-high transition of the

clock inputs.