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 E
1
E
2
D
n
Q
n
(register)
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
q
n
q
n
3-STATE BUFFER OPERATING MODES
INPUTS OUTPUTS
Q
n
(register) OE
1
OE
2
Q
0
Q
1
Q
2
Q
3
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.
