MM74C922 Replacement IC 16 Key Keyboard Encoder

This is a drop in replacement for the 74C922.

The 74C922-SO is a custom programmed microprocessor designed to emulate the 74C922 surface mount chip that is no longer available. This part is in full production, and large quantities are available. Encode your keyboard or keypad of up to 16 keys with no additional parts required.

Functional Description

The 74C922-SO contains all the logic necessary to encode a SPST keyboard switch array and provide a 4 bit parallel output and a data available signal. The data available signal goes high when a key is pressed, and goes low before another key output is generated. The data output pins keep their state even after the key is released. The array is often a 4 x 4 array, but smaller arrays such as a 3 x 4 array or smaller can be used. The 74C922-SO handles debouncing the keys as well. No external capacitors are required for timing, all timing is internally generated. No external diodes are required in the array to prevent ghosting in a two key rollover situation. A .1 uF capacitor is suggested across the VDD and ground pins. Although a functional replacement, this part only allows a power supply voltage of 3-5.25 volts and the outputs are not tristate.

Need serial output? Larger matix size? Check out our other keyboard encoders at:


Part Number 74C922-SO

1-9 - $9.00 (+$3 S/H USA)

10-99 - $8.00 (USA Shipping included)

100 - $6.00 (USA Shipping included)

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Custom Keyboard encoders

We can also design keyboard encoders to meet your specifications at low cost, email us your specifications for more details.

Keyboard encoder technical documents

Spec sheet for the 74C922-SO: 74C922-SO.pdf

Spec sheet for the MM74C922: 74C922.pdf is a part of:

The 74C922 was originally made by National Semiconductor, transferred to Fairchild semiconductor, then bought by Texas Instruments, but are no longer produced.