HIT HD74HC221 Datasheet
HD74HC221
Dual Monostable Multivibrators (with Schmitt Trigger Input)
Description
Each multivibrator features both a negative, A, and a positive, B, transition triggered input, either of which
can be used as an inhibit. Also included is a clear inpt that when taken low resets the one shot. The
HD74HC221 can be triggered on the positive transition of teh clear while A is held low and B is held high.
This device is a non-retriggerable, and therefore cannot be retriggered until the output pulse times out.
The output pulse equation is simply:
tW = 0.7·(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
HD74HC221
Pin Arrangement
1A
1
16
V
CC
Logic Diagram
1B
CLR1
1Q
2Q
Cext 2
2 Rext/
Cext
GND
2
3
CLR
4
5
Q Q
Q
CLR
Q
6
7
8
15
14
13
12
11
10
9
1 Rext/
Cext
1 Cext
1Q
2Q
2CLR
2B
2A
(Top view)
V
CC
Rext
Cext
Clear
2
Cext
Rext
/Cext
A
B
Q
Clear
Q
Q
HD74HC221
DC Characteristics
Ta = –40 to
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 V
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 V
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 supply I
6.0 — — 130 — 220 µA Vin = VCC or GND Iout = 0 µA
CC
current 6.0 — — 130 — 220 Rext/Cent = 0.5 V
+85°C
IL
IL
IOH = –20 µA
IOL = 20 µA
CC
3
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