The KK74HC221A 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. There are two trigger inputs, A INPUT (negative edge) and B INPUT (positive edge). These inputs are valid for rising/falling signals The device may also be triggered by using the RESET input (positiveedge) because of the Schmitt-trigger input; after triggering the output maintains the MONOSTABLE state for the time period determined by the external resistor REXT and capacitor CEXT. Taking RESET low breaks this MONOSTABLE STATE. If the next trigger pulse occurs during the MONOSTABLE period it makes the MONOSTABLE period longer. Outputs Directly Interface to CMOS, NMOS, and TTL Operating Voltage Range: 3.0 to 6.0 V Low Input Current: 1.0 A