74HC123D.653 Datasheet, PDF (15/25 Pages) NXP Semiconductors – Dual retriggerable monostable multivibrator with reset

NXP Semiconductors
74HC123; 74HCT123
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)
123
1 (9)
nA
nB
2 (10)
13 (5)
nQ
4 (12)
nQ
3 (11)
nRD
001aaa854
(1) For minimum noise generation it is recommended to ground pins 6 (2CEXT) and 14 (1CEXT)
externally to pin 8 (GND).
Fig 13. Timing component connections
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.
CEXT
REXT
V_CC
GND nCEXT nREXT/CEXT
8
14 (6)
15 (7)
123
nA
1 (9)
nB
2 (10)
13 (5)
nQ
4 (12)
nQ
3 (11)
nRD
RESET
V_CC
Fig 14. Power-up output pulse elimination circuit
001aaa613
74HC_HCT123
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 8 — 16 December 2011
© NXP B.V. 2011. All rights reserved.
15 of 25