MM74C922 • MM74C923 16-Key Encoder • 20-Key Encoder October 1987 Revised January 1999 MM74C922 • MM74C923 16-Key Encoder • 20-Key Encoder General Description com The MM74C922 and MM74C923 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 50 kΩ 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 Availa...

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