Philips Semiconductors

Product specification

74F776

Pi–bus transceiver

December 19, 1990

5

FUNCTION TABLE

INPUTS

LATCH

OUTPUTS

OPERATING MODE

An

Bn*

LE

OEA

OEB0

OEB1

STATE

An

Bn

H

X

L

L

L

L

H

Z

Z

A 3–state, data from A to B

L

X

L

L

L

L

L

Z

L

X

X

H

L

L

L

Qn

Z

Qn

A 3–state, latched data to B

–

–

L

H

L

L

(1)

(1)

(1)

Feedback: A to B, B to A

–

H

H

H

L

L

H (2)

H

Z(2)

Preconditioned latch enabling data transfer from B to A

–

L

H

H

L

L

H (2)

L

Z(2)

–

–

H

H

L

L

Qn

Qn

Qn

Latch state to A and B

H

X

L

L

H

X

H

Z

Z

L

X

L

L

H

X

L

Z

Z

B and A 3–state

X

X

H

L

H

X

Qn

Z

Z

–

H

L

H

H

X

H

H

Z

–

L

L

H

H

X

L

L

Z

B 3–state, data from B to A

–

H

H

H

H

X

Qn

H

Z

–

L

H

H

H

X

Qn

L

Z

H

X

L

L

X

H

H

Z

Z

L

X

L

L

X

H

L

Z

Z

B and A 3–state

X

X

H

L

X

H

Qn

Z

Z

–

H

L

H

X

H

H

H

Z

–

L

L

H

X

H

L

L

Z

B 3–state, data from B to A

–

H

H

H

X

H

Qn

H

Z

–

L

H

H

X

H

Qn

L

Z

Notes to function table

H = High voltage level

L

= Low voltage level

X = Don’t care

–

= Input not externally driven

Z = High impedance ”off” state

(1) = Condition will cause a feedback loop path: A to B and B to A.

(2) = The latch must be preconditioned such that B inputs may assume a high or low level while OEB0 and OEB1 are low and LE is high.

B* = Precaution should be taken to insure the B inputs do not float. If they do they are equal to low state.