Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 KBDP64 IC Parallel output keyboard encoder for up to 64 keys General Description The KBDP64 IC is designed to provide a parallel binary output encoder for keyboards up to 64 keys. The KBDP64 IC contains all the logic necessary to encode a SPST keyboard switch array up to 8 by 8 in size and provide a parallel binary output and a data available strobe. The data available strobe goes high when a key is pressed, and goes low when the key is released. The data outputs keep their states after the key is released. The array can be a 8 x 8 array, but any smaller size may be used. The KBDP64 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 28 pin .3 inch width SOIC package. Features • Parallel data output plus data available strobe. • • • • • • • • • • • • • Fully encodes a key switch array. (up to 8 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. Applications • Data Entry • Security Alarms • Handheld devices • Machine Control • Numeric Entry • Telephones • Computers • Controls • Gaming On chip row input resistors. Internal key bounce elimination. TTL and CMOS compatible outputs. Part is in full production. SOIC and DIP 28 Pin Package. ROHS Compliant Low EMI Part Number 74C922-SO Copyright © 2014 ABCircuits. Revised September 2014 Page 1 of 7 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Example Circuit DATA AVILABLE DATA OUT F DATA OUT E KBDP64 1 2 3 4 5 6 7 8 9 10 11 12 13 14 DATAAVAIL DOUTF DOUTD DOUTB ROWY8 ROWY6 ROWY4 ROWY2 NC COLX8 COLX6 COLX4 COLX2 VSS VDD NC DOUTE DOUTC DOUTA ROWY7 ROWY5 ROWY3 ROWY1 NC COLX7 COLX5 COLX3 COLX1 DATA OUT D VCC 28 27 26 25 24 23 22 21 20 19 18 17 16 15 DATA OUT C DATA OUT B DATA OUT A C1 00 01 02 03 C2 08 09 0A C3 10 11 C4 18 19 C5 C6 C7 C8 R8 07 0B 0C 0D 0E 0F 13 15 16 17 1A 1B 1C 1D 1E 1F 25 26 27 14 24 05 R7 06 12 04 R6 R5 R4 R3 R2 R1 KEYPAD 20 21 22 23 28 29 2A 2B 2C 2D 2E 2F 30 31 32 33 35 36 37 38 39 3A 3B 3C 3D 3E 3F 34 Part Number KBDP64 Copyright © 2014 ABCircuits. Revised September 2014 Page 2 of 7 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Connection Diagram KBDP64 1 2 3 4 5 6 7 8 9 10 11 12 13 14 DATAAVAIL DOUTF DOUTD DOUTB ROWY8 ROWY6 ROWY4 ROWY2 NC COLX8 COLX6 COLX4 COLX2 VSS VDD NC DOUTE DOUTC DOUTA ROWY7 ROWY5 ROWY3 ROWY1 NC COLX7 COLX5 COLX3 COLX1 28 27 26 25 24 23 22 21 20 19 18 17 16 15 Pin Description Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Description Data Avail DOut F (MSB) DOut D DOut B Row Y8 Row Y6 Row Y4 Row Y2 NC Col X8 Col X6 Col X4 Col X2 VSS Pin # 28 27 26 25 24 23 22 21 20 19 18 17 16 15 Description VDD NC DOut E DOut C DOut A (LSB) Row Y7 Row Y5 Row Y3 Row Y1 NC Col X7 Col X5 Col X3 Col X1 Col X1 – Col X8 These pins are open drain column driver outputs to the key matrix. Row Y1 – Row Y8 These pins are the row inputs from the key matrix. These inputs have 5.6K (nominal) pull up resistors on chip. DOUTA - DOUTF These are the parallel data outputs. DOut A is the least significant bit. These bits form a binary code for the pressed key. These outputs keep their state even after the key is released. Data Avail This pin goes high when a key is pressed, and low when the key is released. In the case of a 2 key rollover, the pin goes low before the DOut bits change, then goes high again. VSS Connect to system ground. Part Number KBDP64 Copyright © 2014 ABCircuits. Revised September 2014 Page 3 of 7 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 VDD Connect to supply voltage of 2.4 to 5 volts. A .1 uF decoupling capacitor to ground is recommended. NOTES: Make no connection to the NC pins. Pins 9 and 19 must be left unconnected. Truth Table The output codes of the KBD64 start at zero, and progress upwards in a binary count. The hex output of the DOut bits is shown in the right column. Custom output codes are available, consult the factory for information. COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX1 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX2 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX3 COLX4 COLX4 COLX4 COLX4 COLX4 COLX4 COLX4 COLX4 COLX5 COLX5 COLX5 COLX5 COLX5 ROWY1 X ROWY2 ROWY3 ROWY4 ROWY5 ROWY6 ROWY7 ROWY8 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Part Number KBDP64 Copyright © 2014 ABCircuits. Revised September 2014 Page 4 of 7 HEX 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 23 24 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 COLX5 COLX5 COLX5 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX6 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX7 COLX8 COLX8 COLX8 COLX8 COLX8 COLX8 COLX8 COLX8 X X X X X X X X X X X X X X X X X X X X X X X X X X X 25 26 27 28 29 2A 2B 2C 2D 2E 2F 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F Absolute Maximum Ratings Symbol Description Tstg Ta V dd V io Imio ESD Storage Temperature Operating Temperature LU Latch up current V dd - V ss Voltage Input Voltage Maximum current into any pin Electrostatic Discharge Voltage Min -55 -40 -0.5 Vss - 0.5 -25 2000 Typical Max Units 25 +100 +85 +6.0 ºC ºC V V mA V V dd +0.5 +50 200 Notes Human Body Model ESD mA Part Number KBDP64 Copyright © 2014 ABCircuits. Revised September 2014 Page 5 of 7 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 DC Electrical Characteristics Symbol Description V dd Idd V oh V ol V ih V il Ioh Iol Cio Iil Rpu Supply Voltage Supply Current High Output Level Low Output Voltage Input High Level Input Low Level High Level Source Current Low Level Sink Current Capacitive load Input leakage Pull Up Resistors On Row Inputs Min Typical Max Units 2 5.25 8 V mA V V V V mA mA pF nA k? 2.4 V dd - 1.0 0.75 2.1 4 3.5 1 5.6 0.8 10 25 10 8 Notes Note 1 Ioh=10 mA Iol=25 mA Note 1: Vdd=5VDC, all inputs and outputs open 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. Part Number KBDP64 Copyright © 2014 ABCircuits. Revised September 2014 Page 6 of 7 Turning Ideas Into Reality ABCircuits www.abcircuits.com POB 123 New Hill NC 27562 (919) 290-7104 Physical Dimensions SOIC-28 Physical Dimensions 28 Pin Dip Package (-DIP Suffix) Close but not quite? Our products are software based, we can modify existing parts to fit your needs at a minimal cost or create new parts designed to your specifications. Email us and we can make a chip for you! For the latest version of this spec sheet, visit www.abcircuits.com Design Services Available We can quickly turn your idea into a chip, a pc board, or a finished product. Contact us with your needs and specifications. Part Number KBDP64 Copyright © 2014 ABCircuits. Revised September 2014 Page 7 of 7