HD74HC123A
Dual Retriggerable Monostable Multivibrators (with Clear)
Description
This multivibrator features both a negative, A, and a positive, B, transition triggered input, either of which
can be used as an inhibit input. Also included is a clear input that when taken low resets the one shot. The
HD74HC123A can be triggered on the positive transition of the clear while A is held low and B is held
high.
The HD74HC123A is retriggerable. That is it may be triggered repeatedly while their outputs are
generating a pulse and the pulse will be extended.
Pulse width stability over a wide range of temperature. The output pulse equation is simply: t
w
= (Rext)
(Cext).
Features
•
•
•
•
•
High Speed Operation
High Output Current: Fanout of 10 LSTTL Loads
Wide Operating Voltage: V
CC
= 2 to 6 V
Low Input Current: 1 µA max
Low Quiescent Supply Current
Function Table
Inputs
Clear
L
X
X
H
H
L
A
X
H
X
L
H
H
B
X
X
L
Outputs
Q
L
L
L
Q
H
H
H
Note: External timing capacitance connects between Cext and Rext/Cext.
HD74HC123A
Pin Arrangement
1A
1B
1CLR
1Q
2Q
2Cext
2Rext/
Cext
GND
1
2
3
4
5
6
7
8
(Top view)
Q
Q
CLR
CLR
Q
16 V
CC
15 1Rext
Cext
Q
14 1Cext
13 1Q
12 2Q
11 2CLR
10 2B
9
2A
2
HD74HC123A
DC Characteristics
Sym-
Item
Input voltage
bol
V
IH
V
CC
(V)
2.0
4.5
6.0
V
IL
2.0
4.5
6.0
Output voltage
V
OH
2.0
4.5
6.0
4.5
6.0
V
OL
2.0
4.5
6.0
4.5
6.0
Input current
Quiescent
supply current
Standby state
Active state
Iin
I
CC
6.0
6.0
Ta = 25°C
Ta = –40
to +85°C
Min Typ Max Min Max Unit Test Conditions
1.5
—
—
—
—
0.5
1.5
—
V
3.15 —
4.2
—
—
—
1.9
4.4
5.9
—
—
—
—
2.0
4.5
6.0
3.15 —
4.2
—
—
0.5
1.35
1.8
—
—
—
I
OH
= –4 mA
I
OH
= –5.2 mA
V
Vin = V
IH
or V
IL
I
OL
= 20
µA
V
Vin = V
IH
or V
IL
I
OH
= –20
µA
V
1.35 —
1.8
—
—
—
—
—
0.1
0.1
0.1
—
1.9
4.4
5.9
4.18 —
5.68 —
—
—
—
—
—
—
—
—
0.0
0.0
0.0
—
—
—
—
—
4.13 —
5.63 —
—
—
—
0.1
0.1
0.1
0.33
0.33
±1.0 µA
220
µA
220
0.26 —
0.26 —
±0.1
—
130
130
—
—
I
OL
= 4 mA
I
OL
= 5.2 mA
Vin = V
CC
or GND
Vin = V
CC
or
GND
Iout = 0
µA
Rext/Cext = 0.5 V
CC
3
HD74HC123A
AC Characteristics
(C
L
= 50 pF, Input t
r
= t
f
= 6 ns)
Ta = 25°C
Item
Symbol
Ta = –40 to
+85°C
Max
265
53
45
300
60
51
215
43
37
225
45
38
95
19
16
95
19
16
—
—
—
—
—
—
—
10
ms
pF
Cext = 0.1
µF,
Rext = 10 kΩ
µs
ns
Cext = 28 pF
Rext = 6 kΩ
Rext = 2 kΩ
ns
A, B, Clear
ns
ns
ns
Clear to
Q
ns
Clear to Q
ns
A, B or Clear to
Q
Unit
ns
Test Conditions
A, B or Clear to Q
V
CC
(V) Min Typ Max Min
2.0
4.5
6.0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
22
—
—
23
—
—
18
—
—
16
—
—
5
—
—
5
—
210 —
42
36
—
—
Propagation delay t
PLH
time
t
PHL
2.0
4.5
6.0
240 —
48
41
—
—
t
PHL
2.0
4.5
6.0
170 —
34
29
—
—
t
PLH
2.0
4.5
6.0
180 —
36
31
75
15
13
75
15
13
—
—
—
—
—
—
—
—
—
—
—
190
38
33
—
—
—
—
—
Output rise time
t
TLH
2.0
4.5
6.0
Output fall time
t
THL
2.0
4.5
6.0
Pulse width
t
w
2.0
4.5
6.0
150 —
30
26
—
—
—
—
—
6
—
Minimum output
pulse width
t
WQ(min)
2.0
4.5
6.0
1.5 —
450 —
380 —
1.0 —
5
10
Output pulse width t
WQ
Input capacitance
Caution in use:
Cin
4.5
—
In order to prevent any malfunctions due to noise, connect a high-frequency performance
capacitor between V
CC
and GND, and keep the wiring between the External components
and Cext, Rext/Cext pins as short as possible.
4
19.20
20.00 Max
16
9
7.40 Max
6.30
Unit: mm
1
1.3
1.11 Max
8
0.51 Min
2.54 Min 5.06 Max
7.62
2.54
±
0.25
0.48
±
0.10
0.25
– 0.05
0° – 15°
Hitachi Code
JEDEC
EIAJ
Weight (reference value)
+ 0.13
DP-16
Conforms
Conforms
1.07 g
