This part is a kind of semiconductor called 74HC4538.

Function of this product has Dual retriggerable precision monostable multivibrator.

Manufacturers : Toshiba

Image and pinout :

Some of the text within the PDF file :

TC74HC4538AP/AF/AFT TOSHIBA CMOS Digital Integrated Circuit Silicon Monolithic TC74HC4538AP,TC74HC4538AF,TC74HC4538AFT Dual Retriggerable Monostable Multivibrator The TC74HC4538A is a high speed CMOS MONOSTABLE MULTIVIBRATOR fabricated with silicon gate C2MOS technology. It achieves the high speed operation similar to equivalent LSTTL while maintaining the CMOS low power dissipation. There are two trigger inputs, A input (positive edge input), and B input (negative edge input). These inputs are valid for a slow rise/fall time signal (tr = tf = 1 s) as they are schmitt trigger inputs. After triggering, the output stays in a MONOSTABLE state for the time period determined by the external resistor and capacitor (RX, CX). A low level at CD input breaks this STABLE STATE. In the MONOSTABLE sta [ ... ]

74HC4538 PDF Datasheet Download