The IN74HC221 is identical in pinout to the LS/ALS221. The device inputs are compatible with standard CMOS outputs; with pullup resistors, they are compatible with LS/ALSTTL outputs.

• Outputs Directly Interface to CMOS, NMOS, and TTL
• Operating Voltage Range: 3.0 to 6.0 V
• Low Input Current: 1.0 µA
• High Noise Immunity Characteristic of CMOS Devices