74HC123; 74HCT123
NXP Semiconductors
Dual retriggerable monostable multivibrator with reset
12.3 Power-down considerations
A large capacitor CEXT 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 VCC 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 (DEXT) preferably a germanium or Schottky type
diode able to withstand large current surges and connect as shown in Figure 15.
D
EXT
C
EXT
R
EXT
V
CC
GND
8
nCEXT
14 (6)
nREXT/CEXT
15 (7)
13 (5)
123
nQ
1 (9)
nA
nB
2 (10)
4 (12)
nQ
3 (11)
001aaa614
nRD
Fig 15. Power-down protection circuit
74HC_HCT123
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© NXP B.V. 2011. All rights reserved.
Product data sheet
Rev. 8 — 16 December 2011
16 of 25
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