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ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104

Part Number KBDP64

DC Electrical Characteristics

Symbol

Description

Min

Typical

Max

Units

Notes

Supply Voltage

2.4

5.25

V

Supply Current

2

8

mA

High Output Level

V

Low Output Voltage

0.75

V

Input High Level

2.1

V

Input Low Level

0.8

V

High Level Source Current

10

mA

Low Level Sink Current

25

mA

Capacitive load

3.5

10

pF

Input leakage

1

nA

Pull Up Resistors On Row Inputs

4

5.6

8

k?

Theory Of Operation

The KBDP64 IC is a custom programmed microprocessor designed to encode keyboards and

provide a parallel output. The open drain COL X pins are pulsed low one at a time, and the ROW

Y pins are sampled to check for key switch closures. If a key is detected, scanning stops until the

key is released. The pressed key is encoded and placed on the DOut pins, and the Data Avail

strobe is set high. When the key is released the Data Avail strobe is set low and scanning

continues.