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NTE74C922 & NTE74C923 Integrated Circuit
TTL− CMOS Key Encoders
Description: The NTE74C922 (16−Key, 18−Lead DIP) and NTE74C923 (20−Key, 20−Lead DIP) CMOS key encoders provide all the necessary logic to fully encode an array of SPST switches. The keyboard scan can be implemented by either an external clock or external capacitor. These encoders also have on− chip pull−up devices which permit switches with up to 50kΩ on resistance to be used. No diodes in the switch array are needed to eliminate ghost switches. The internal debounce circuit needs only a single external capacitor and can be defeated by omitting the capacitor. A Data Available output goes to a high level when a valid keyboard entry has been made.
NTE74C922 Datasheet
