74HC_HCT221_CNV_15 Datasheet, PDF (4/15 Pages) NXP Semiconductors – Dual non-retriggerable monostable multivibrator with reset

Philips Semiconductors
Dual non-retriggerable monostable
multivibrator with reset
Product specification
74HC/HCT221
Fig.4 Functional diagram.
FUNCTION TABLE
INPUTS
nR_D
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
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