CY54/74FCT646T

2

BUS B

BUS A

DIR

L

G

L

CPAB

X

CPBA

X

SAB

X

SBA

L

BUS B

BUS A

DIR

H

L

X

G

L

L

H

CPAB

X

CPBA

X

SAB

X

X

X

SBA

X

X

X

BUS B

BUS A

DIR

H

G

L

CPAB

X

CPBA

X

SAB

L

SBA

X

BUS A

BUS A

DIR

L

H

G

L

L

CPAB

X

Hor L

CPBA

Hor L

X

SAB

X

H

SBA

H

X

Real-Time Transfer

Bus B to Bus A

Real-Time Transfer

Bus A to Bus B

Storage from

A and/or B

Transfer Stored Data

to A and/or B

[1]

Inputs

Operation or Function

G

DIR

CPAB

CPBA

SAB

SBA

FCT646T

H

H

X

X

H or L

H or L

X

X

X

X

Input

Input

Isolation

Store A and B Data

L

L

L

L

X

X

X

H or L

X

X

L

H

Output

Input

Real Time B Data to A Bus

Stored B Data to A Bus

L

L

H

H

X

H or L

X

X

L

H

X

X

Input

Output

Real Time A Data to B Bus

Stored A Data to B Bus

Notes:

1.

Cannot transfer data to A bus and B bus simultaneously.

2.

H = HIGH Voltage Level, L = LOW Voltage Level,

= LOW-to-HIGH Transition, X = Don’t Care.

3.

The data output functions may be enabled or disabled by various signals at the G or DIR inputs. Data input functions are always enabled, i.e., data at the bus

pins will be stored on every LOW-to-HIGH transition of the clock inputs.