74HC423D.653 Datasheet, PDF (14/24 Pages) NXP Semiconductors – Dual retriggerable monostable multivibrator with reset

NXP Semiconductors
74HC423; 74HCT423
Dual retriggerable monostable multivibrator with reset
12. Application information
12.1 Timing component connections
The basic output pulse width is essentially determined by the values of the external timing
components R_EXT and C_EXT.
(1) ^CEXT
REXT
V_CC
GND nCEXT nREXT/CEXT
8
14 (6) 15 (7)
423
nA
1 (9)
13 (5)
nQ
nB
2 (10)
4 (12)
nQ
3 (11)
nRD
001aah917
(1) For minimum noise generation it is recommended that the nCEXT pins (6, 14) are connected to ground externally to
the GND pin (8).
Fig 13. Timing component connections
12.1.1 Minimum monostable pulse width
To set the minimum pulse width, when C_EXT < 10 nF, see Figure 8 and
when C_EXT > 10 nF, the output pulse width is defined as:
t_W = 0.45  R_EXT  C_EXT (typ.), where:
t_W = pulse width in s;
R_EXT = external resistor in k;
C_EXT = external capacitor in nF.
12.2 Power-up considerations
When the monostable is powered-up it may produce an output pulse, with a pulse width
defined by the values of R_EXT and C_EXT, this output pulse can be eliminated using the
circuit shown in Figure 14.
74HC_HCT423
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 6 — 19 December 2011
© NXP B.V. 2011. All rights reserved.
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