74C922-SO中文资料IC Keyboard Encoder for up to 16 switches MM74C922 Replacement IC数据手册ABCircuits规格书

描述 Description

The 74C922-SO is designed as a replacement chip for the obsolete MM74C922 surface mount part. The 74C922-SO contains all the logic necessary to encode a SPST keyboard switch array up to 4 by 4 in size 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 can be a 4 x 4 array, but smaller arrays such as a 3 x 4 array or any smaller size can be used. The 74C922-SO handles debouncing of 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 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.

特性 Features

• Replacement Chip for MM74C922
• Fully encodes a key switch array. (up to 4 x 4)
• No external parts required.
• Low power consumption 1.5 mA typical.
• Supply voltage 2.4 to 5.25 volts.
• Last key pressed retained on data outputs.
• 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.
• Low EMI.
• ROHS Compliant.