Table of Contents

1 Features............................................................................1

2 Applications..................................................................... 1

3 Description.......................................................................1

4 Revision History.............................................................. 2

5 Pin Configuration and Functions...................................3

Pin Functions.................................................................... 3

6 Specifications.................................................................. 4

6.1 Absolute Maximum Ratings........................................ 4

6.2 ESD Ratings............................................................... 4

6.3 Recommended Operating Conditions.........................4

6.4 Thermal Information....................................................5

6.5 Electrical Characteristics.............................................5

6.6 Switching Characteristics............................................5

6.7 Operating Characteristics........................................... 6

6.8 Typical Characteristics................................................ 6

7 Parameter Measurement Information............................ 7

8 Detailed Description........................................................8

8.1 Overview..................................................................... 8

8.2 Functional Block Diagram........................................... 8

8.3 Feature Description.....................................................8

8.4 Device Functional Modes............................................9

9 Application and Implementation.................................. 10

9.1 Application Information............................................. 10

9.2 Typical Application.................................................... 10

10 Power Supply Recommendations..............................12

11 Layout........................................................................... 13

11.1 Layout Guidelines................................................... 13

11.2 Layout Example...................................................... 13

12 Device and Documentation Support..........................14

12.1 Documentation Support.......................................... 14

12.2 Related Links.......................................................... 14

12.3 Support Resources................................................. 14

12.4 Trademarks.............................................................14

12.5 Electrostatic Discharge Caution..............................14

12.6 Glossary..................................................................14

13 Mechanical, Packaging, and Orderable

Information.................................................................... 14

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision C (September 2003) to Revision D (June 2020)

Page

• Updated to new data sheet standards................................................................................................................ 1

• Moved the HCT devices to a standalone data sheet (SCHS418) ......................................................................1

• RθJA increased for the D package from 86 to 133.6 ℃/W and decreased for the N package from 80 to 65.2

℃/W....................................................................................................................................................................5

CD74HC21, CD54HC21

SCHS131D – AUGUST 1997 – REVISED MAY 2021

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