The TC74HC40102A and TC74HC40103A are high speed CMOS PROGRAMMABLE DOWN COUNTERS fabricated with silicon gate C2MOS technology. They achieve the high speed operation similar to equivalent LSTTL while maintaining the CMOS low power dissipation. The output terminal ( CO/ZD ) goes to an active low state when the down count reaches zero. Since the TC74HC40102A is designed as a BCD counter, programming up to 99 counts is possible. The TC74HC40103A, with its 8-bit binary construction, can be set to provide up to 255 counts. Both devices have Inhibit Clock ( CI/CE ), Asynchronous Preset Control ( APE ), Synchronous Preset ( SPE ) and Clear Control ( CLR ) inputs for setting the counter to the maximum counting mode.