SL74HC651

System Logic

Semiconductor

SLS

FUNCTION TABLE

Dir.

OE

CAB CBA

SAB

SBA

A

B

FUNCTION

INPUTS

INPUTS

Both the A bus and the B bus are inputs.

L

H

X

X

X

X

Z

Z

The output functions of the A and B bus

are disabled.

X

X

INPUTS

INPUTS

Both the A and B bus are used for inputs

to the internal flip-flops. Data at the bus

will be stored on low to high transition of

the clock inputs.

OUTPUTS

INPUTS

The A bus are outputs and the B bus are

inputs.

X

*

X

X

L

H

L

L

H

The data at the B bus are displayed at the

A bus.

L

L

X

*

X

L

H

L

L

H

The data at the B bus are displayed at the

A bus. The data of the B bus are stored to

the internal flip-flops on low to high

transition of the clock pulse.

X

*

X

X

H

Qn

X

The data stored to the internal flip-flops,

are displayed at the A bus.

X

*

X

H

L

H

H

L

The data at the B bus are stored to the

internal flip-flops on low to high transition

of the clock pulse. The states of the

internal flip-flops output directly to the A

bus.

INPUTS

OUTPUTS

The A bus are inputs and the B bus are

outputs.

X

X

*

L

X

H

L

L

H

The data at the A bus are displayed at the

B bus.

H

H

X

*

L

X

H

L

L

H

The data at the B bus are displayed at the

A bus. The data of the B bus are stored to

the internal flip-flops on low to high

transition of the clock pulse.

X

X

*

H

X

X

Qn

The data stored to the internal flip-flops

are displayed at the B bus.

X

*

H

X

H

L

L

H

The data at the A bus are stored to the

internal flip-flops on low to high transition

of the clock pulse. The states of the

internal flip-flops output directly to the B

bus.

OUTPUTS

OUTPUTS

Both the A bus and the B bus are outputs

H

L

X

X

H

H

Qn

Qn

The data stored to the internal flip-flops

are displayed at the A and B bus

respectively.

H

H

Qn

Qn

The output at the A bus are displayed at

the B bus, the output at the B bus are

displayed at the A bus respec.

X : DON’T CARE

Z : HIGH IMPEDANCE

Qn : THE DATA STORED TO THE INTERNAL FLIP-FLOPS BY MOST RECENT LOW TO HIGH TRANSITION

OF THE CLOCK INPUTS

TRANSITION OF THE CLOCK INPUTS