Datasheet

74HC_HCT123 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet Rev. 9 — 19 January 2015 16 of 25
NXP Semiconductors
74HC123; 74HCT123
Dual retriggerable monostable multivibrator with reset
12.3 Power-down considerations
A large capacitor C
EXT
may cause problems when powering-down the monostable due to
the energy stored in this capacitor. When a system containing this device is
powered-down or a rapid decrease of V
CC
to zero occurs, the monostable may sustain
damage, due to the capacitor discharging through the input protection diodes. To avoid
this possibility, use a damping diode (D
EXT
) preferably a germanium or Schottky type
diode able to withstand large current surges and connect as shown in Figure 15
.
Fig 15. Power-down protection circuit
DDD
'
(;7
Q5'
&
(;7
5
(;7
Q$
Q%
9
&&
Q&(;7 Q5(;7&(;7
Q4
Q4







*1'
