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KBDSER56 IC Keyboard Encoder Serial Output for up to 56 keys

General Description

The KBDSER56 IC is designed to provide a serial ASCII output encoder for keyboards up to 56 keys. The KBDSER56 IC contains all the logic necessary to encode a SPST keyboard switch array up to 7 by 8 in size and provide a serial ASCII output. The output is standard asynchronous format, using 8 bits, 1 stop and no parity at 9600 BPS. Other formats and encoding are available, contact the factory. The array can be a 7 x 8 array, but any smaller size may be used. The KBDSER56 IC handles debouncing and encodes the keys with no external parts. All timing is internally generated. No external diodes are required in the array to prevent key ghosting in a two key rollover situation. A .1 uF bypass capacitor is suggested across the VDD and VSS pins. The part uses the standard 20 pin .3 inch width SOIC and DIP package.


  • Asynchronous serial output.
  • Fully encodes a key switch array. (up to 7 x 8)
  • No external parts required.
  • Low power consumption 5 mA typical.
  • Supply voltage 2.4 to 5.25 volts.
  • All timing internally generated.
  • 2 Key rollover.
  • On chip row input resistors.
  • Internal key bounce elimination.
  • TTL and CMOS compatible outputs.
  • Part is in full production.
  • SOIC and DIP 20 Pin Package.
  • ROHS Compliant
  • Low EMI

Example Circuits

Spec sheet: Keyboard Encoder Serial output 56 keys

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