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74F776

Pi-bus transceiver

Philips Electronics 

Philips Semiconductors

Pi–bus transceiver

Product specification

74F776

FUNCTION TABLE

INPUTS

LATCH OUTPUTS

OPERATING MODE

An Bn* LE OEA OEB0 OEB1 STATE An Bn

HX L

L

L

L

H

Z Z A 3–state, data from A to B

LXL

L

L

L

L

ZL

XXH

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

– HH

H

L

L

H (2)

H Z(2) Preconditioned latch enabling data transfer from B to A

– LH

H

L

L

H (2)

L Z(2)

– –H

H

L

L

Qn

Qn Qn Latch state to A and B

HX L

L

H

X

H

ZZ

LXL

L

H

X

L

Z Z B and A 3–state

XXH

L

H

X

Qn

ZZ

–HL

H

H

X

H

HZ

–LL

H

H

X

L

L Z B 3–state, data from B to A

– HH

H

H

X

Qn

HZ

– LH

H

H

X

Qn

LZ

HX L

L

X

H

H

ZZ

LXL

L

X

H

L

Z Z B and A 3–state

XXH

L

X

H

Qn

ZZ

–HL

H

X

H

H

HZ

–LL

H

X

H

L

L Z B 3–state, data from B to A

– HH

H

X

H

Qn

HZ

– LH

H

X

H

Qn

LZ

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

Qn = High or Low voltage level one setup time prior to the low–to–high LE transition.

(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.

December 19, 1990

5

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