mm74c923wmx-nl Fairchild Semiconductor, mm74c923wmx-nl Datasheet

mm74c923wmx-nl

Manufacturer Part Number

mm74c923wmx-nl

Description

Mm74c922 * Mm74c923 16-key Encoder * 20-key Encoder

Manufacturer

Fairchild Semiconductor

Datasheet

1.MM74C923WMX-NL.pdf (11 pages)

Current page: 1 of 11
Download datasheet (129Kb)

MM74C922WM

MM74C922N

MM74C923WM

MM74C923N

MM74C922 • MM74C923

16-Key Encoder • 20-Key Encoder

General Description

The MM74C922 and MM74C923 CMOS key encoders pro-

vide all the necessary logic to fully encode an array of

SPST switches. The keyboard scan can be implemented

by either an external clock or external capacitor. These

encoders also have on-chip pull-up devices which permit

switches with up to 50 k

diodes in the switch array are needed to eliminate ghost

switches. The internal debounce circuit needs only a single

external capacitor and can be defeated by omitting the

capacitor. A Data Available output goes to a high level

when a valid keyboard entry has been made. The Data

Available output returns to a low level when the entered

key is released, even if another key is depressed. The Data

Available will return high to indicate acceptance of the new

key after a normal debounce period; this two-key roll-over

is provided between any two switches.

An internal register remembers the last key pressed even

after the key is released. The 3-STATE outputs provide for

easy expansion and bus operation and are LPTTL compat-

ible.

Ordering Code:

Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.

Connection Diagrams

Order Number

Pin Assignment for DIP

Package Number

MM74C922

Top View

M20B

N18B

N20A

on resistance to be used. No

20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide

18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide

20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide

20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

DS006037

Features

50 k

On or off chip clock

On-chip row pull-up devices

2 key roll-over

Keybounce elimination with single capacitor

Last key register at outputs

3-STATE output LPTTL compatible

Wide supply range:

Low power consumption

Package Description

maximum switch on resistance

Pin Assignment for SOIC

MM74C922

Top View

3V to 15V

October 1987

Revised April 2001

www.fairchildsemi.com

Related parts for mm74c923wmx-nl

mm74c923wmx-nl Summary of contents

Page 1

... Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code. Connection Diagrams Pin Assignment for DIP Top View MM74C922 © 2001 Fairchild Semiconductor Corporation Features 50 k maximum switch on resistance On or off chip clock On-chip row pull-up devices ...

Page 2

Connection Diagrams (Continued) Truth Tables (Pins 0 through 11) Switch Position Y1, X1 Y1, X2 Y1, X3 Y1, X4 Y2 ...

Page 3

Block Diagram 3 www.fairchildsemi.com ...

Page 4

Absolute Maximum Ratings Voltage at Any Pin V 0. Operating Temperature Range MM74C922, MM74C923 Storage Temperature Range Power Dissipation ( Dual-In-Line Small Outline Operating V Range Lead Temperature (Soldering, 10 seconds) DC ...

Page 5

DC Electrical Characteristics Symbol Parameter V Logical “0” Output Voltage OUT(0) OUTPUT DRIVE (See Family Characteristics Data Sheet) (Short Circuit Current) I Output Source Current SOURCE (P-Channel) I Output Source Current SOURCE (P-Channel) I Output Sink Current SINK (N-Channel) I ...

Page 6

Switching Time Waveforms T1 T2 RC, T3 0.7 RC, where R 10k and C is external capacitor at KBM input. www.fairchildsemi.com FIGURE 1. FIGURE 2. 6 ...

Page 7

Typical Performance Characteristics Typical Any Y Input rp IN Typical SCAN OSC Typical Applications Synchronous Handshake (MM74C922) The keyboard may be synchronously scanned by omitting the capacitor at osc. and driving osc. directly ...

Page 8

Asynchronous Data Entry Onto Bus (MM74C922) Outputs are in 3-STATE until key is pressed, then data is placed on bus. When key is released, outputs return to 3-STATE. Expansion to 32 Key Encoder (MM74C922) Theory of Operation The MM74C922/MM74C923 Keyboard ...

Page 9

Physical Dimensions inches (millimeters) unless otherwise noted 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" Wide Package Number M20B 9 www.fairchildsemi.com ...

Page 10

Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide www.fairchildsemi.com Package Number N18B 10 ...

Page 11

Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right ...

Related keywords

mm74c923wmx-nl datasheet
mm74c923wmx-nl data sheet
mm74c923wmx-nl pdf datasheet
mm74c923wmx-nl component
mm74c923wmx-nl part
mm74c923wmx-nl distributor
mm74c923wmx-nl RoHS
mm74c923wmx-nl datasheet download