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

Philips Semiconductors
Dual non-retriggerable monostable
multivibrator with reset
Product specification
74HC/HCT221
Fig.15 Typical output pulse width as a function of
temperature; C_X = 0.1 µF; R_X = 10 KΩ;
V_CC = 5 V.
Fig.16 k factor as a function of supply voltage;
R_X = 10 KΩ; T_amb = 25 °C.
Power-down consideration
A large capacitor (C_X) 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 substain damage, due to the
capacitor discharging through the input protection diodes.
To avoid this possibility, use a damping diode (D_X)
preferably a germanium or Schottky type diode able to
withstand large current surges and connect as shown in
Fig.17.
PACKAGE OUTLINES
See “74HC/HCT/HCU/HCMOS Logic Package Outlines”.
Fig.17 Power-down protection circuit.
December 1990
15