The M74HC221 is an high speed CMOS MONOSTABLE MULTIVIBRATOR fabricated with silicon gate C2MOS technology. There are two trigger inputs, A INPUT (negative edge) and B INPUT (positive edge). Triggering on the B input occurs at a particular voltage threshold and is not related to rise and fall time of the applied pulse. The device may also be trigger by using the CLR input (positive edge) because of the Schimtt-trigger input; after