KBDSER56 Datasheet, PDF (1/7 Pages) ABCircuits – Serial output encoder keyboards up to 56 switches

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KBDSER56 IC
Serial output encoder keyboards up to 56 switches
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 package.
Features
• Asynchronous serial output.
• Fully encodes a key switch array. (up to 7 x 8)
• No external parts required.
• Low power consumption 2 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 20 Pin Package.
• ROHS Compliant
• Low EMI
Part Number KBDSER56
January 2013 Page 1 of 7