74HC221DB View Datasheet(PDF) - Philips Electronics

Part Name

Description

MFG CO.

74HC221DB

Dual Monostable Multivibrators (with Schmitt Trigger Input)

Philips Electronics 

Philips Semiconductors

Dual non-retriggerable monostable

multivibrator with reset

Product specification

74HC/HCT221

Fig.4 Functional diagram.

FUNCTION TABLE

INPUTS

nRD

nA

L

X

X

H

X

X

H

L

H

↓

↑

L

OUTPUTS

nB nQ

nQ

X

L

X

L (2)

L

L (2)

H

H (2)

H (2)

↑

H

H

(3)

(3)

Notes

1. H = HIGH voltage level

L = LOW voltage level

X = don’t care

↑ = LOW-to-HIGH level

↓ = HIGH-to-LOW level

= one HIGH-level output pulse

= one LOW-level output pulse

2. If the monostable was triggered before this condition

was established the pulse will continue as

programmed.

3. For this combination the reset input must be LOW and

the following sequence must be used:

pin 1 (or 9) must be set HIGH or pin 2 (or 10) set LOW;

then pin 1 (or 9) must be LOW and pin 2 (or 10) set

HIGH. Now the reset input goes from LOW-to-HIGH

and the device will be triggered.

December 1990

4

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