tc74hc423ap TOSHIBA Semiconductor CORPORATION, tc74hc423ap Datasheet - Page 2

• Manufacturer Part Number: tc74hc423ap
• Description: Dual Retriggerable Monostable Multivibrator
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Pin Assignment
IEC Logic Symbol
Block Diagram (Note 1)(Note 2)
Note 1: Cx, Rx, Dx are external
Note 2: External clamping diode, Dx;
capacitor, resistor, and diode, respectively.
The external capacitor is charged to V
If the supply voltage is turned off, Cx is discharges mainly through the internal (parasitic) diode. If Cx is
sufficiently large and V
current or latch-up. If the capacitance of the supply voltage filter is large enough and V
in rush current is automatically limited and damage to the IC is avoided.
The maximum value of forward current through the parasitic diode is ±20 mA.
In the case of a large Cx, the limit of fall time of the supply voltage is determined as follows:
In the event a system does not satisfy the above condition, an external clamping diode (Dx) is needed to
protect the IC from in rush current.
t
(tf is the time between the supply voltage turn off and the supply voltage reaching 0.4 V
f
≥ (V
CC
− 0.7) Cx/20 mA
CC
drops rapidly, there will be some possibility of damaging the IC through in rush
CC
level in the wait state, i.e. when no trigger is applied.
2
TC74HC423AP/AF
CC
drops slowly, the
CC
2007-10-01
.)