This part is a kind of semiconductor called 74HC4538.
Function of this product has Dual retriggerable precision monostable multivibrator.
Manufacturers : Fairchild
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MM74HC4538 Dual Retriggerable Monostable Multivibrator February 1984 Revised August 2000 MM74HC4538 Dual Retriggerable Monostable Multivibrator General Description The MM74HC4538 high speed monostable multivibrator (one shots) is implemented in advanced silicon-gate CMOS technology. They feature speeds comparable to low power Schottky TTL circuitry while retaining the low power and high noise immunity characteristic of CMOS circuits. Each multivibrator features both a negative, A, and a positive, B, transition triggered input, either of which can be used as an inhibit input. Also included is a clear input that when taken low resets the one shot. The MM74HC4538 is retriggerable. That is, it may be triggered repeatedly while their outputs are generating a pulse and the pulse will be extend [ ... ]