December 1990

4

Philips Semiconductors

Product specification

Quad D-type flip-flop; positive-edge trigger; 3-state

74HC/HCT173

FUNCTION TABLE

Notes

1. H = HIGH voltage level

h = HIGH voltage level one set-up time prior to the LOW-to-HIGH CP transition

L = LOW voltage level

I = LOW voltage level one set-up time prior to the LOW-to-HIGH CP transition

q = lower case letters indicate the state of the referenced input (or output)

one set-up time prior to the LOW-to-HIGH CP transition

X = don’t care

Z = high impedance OFF-state

↑ = LOW-to-HIGH CP transition

REGISTER OPERATING MODES

INPUTS

OUTPUTS

MR

CP

reset (clear)

H

X

X

X

X

L

parallel load

L

L

↑

↑

l

l

l

l

l

h

L

H

hold (no change)

L

L

X

X

h

X

X

h

X

X

3-STATE BUFFER OPERATING MODES

INPUTS

OUTPUTS

read

L

H

L

L

L

L

L

H

L

H

L

H

L

H

disabled

X

X

H

X

X

H

Z

Z

Z

Z

Z

Z

Z

Z

Fig.4 Functional diagram.