HIT HD74HC123A Datasheet
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: tw = (Rext)
(Cext).
Features
• High Speed Operation
• High Output Current: Fanout of 10 LSTTL Loads
• Wide Operating Voltage: VCC = 2 to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current
Function Table
Inputs Outputs
Clear A B Q Q
LXXLH
XHXLH
XX L L H
HL
H H
LH
Note: External timing capacitance connects between Cext and Rext/Cext.
HD74HC123A
Pin Arrangement
1A
2Rext/
Cext
1
21B
31CLR
41Q
52Q
62Cext
7
8GND
CLR
Q Q
QQ
CLR
(Top view)
16
15
V
CC
1Rext
Cext
1Cext14
1Q13
2Q12
2CLR11
2B10
2A9
2
HD74HC123A
DC Characteristics
Ta = –40
Sym- VCCTa = 25°C
Item bol (V) Min Typ Max Min Max Unit Test Conditions
Input voltage V
2.0 1.5 — — 1.5 — V
IH
4.5 3.15 — — 3.15 —
6.0 4.2 — — 4.2 —
V
2.0 — — 0.5 — 0.5 V
IL
4.5 — — 1.35 — 1.35
6.0 — — 1.8 — 1.8
Output voltage V
2.0 1.9 2.0 — 1.9 — V Vin = VIH or VILIOH = –20 µA
OH
4.5 4.4 4.5 — 4.4 —
6.0 5.9 6.0 — 5.9 —
4.5 4.18 — — 4.13 — IOH = –4 mA
6.0 5.68 — — 5.63 — IOH = –5.2 mA
V
2.0 — 0.0 0.1 — 0.1 V Vin = VIH or VILIOL = 20 µA
OL
4.5 — 0.0 0.1 — 0.1
6.0 — 0.0 0.1 — 0.1
4.5 — — 0.26 — 0.33 IOL = 4 mA
6.0 — — 0.26 — 0.33 IOL = 5.2 mA
Input current Iin 6.0 — — ±0.1 — ±1.0 µA Vin = VCC or GND
Quiescent Standby state I
6.0 — — 130 — 220 µA Vin = VCC or Iout = 0 µA
CC
supply current Active state — — 130 — 220 GND Rext/Cext = 0.5 V
to +85°C
CC
3
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