74LS42 Datasheet PDF – BCD/Decimal Decoder – National

What is 74LS42?

This is a BCD to decimal decoder/driver integrated circuit that is commonly used in digital electronics. It is a Multipurpose Decoder designed to accept four BCD inputs and provide ten mutually exclusive outputs.

Function: BCD/Decimal Decoder

Package: DIP, SOP 16 Pin

Manufacturer: National Semicondcutor ( Texas Instruments )

74LS42 datasheet


These BCD-to-decimal decoders consist of eight inverters and ten, four-input NAND gates. The inverters are connected in pairs to make BCD input data available for decoding by the NAND gates. Full decoding of input logic ensures that all outputs remain off for all invalid (10± 15) input conditions.


1. Diode clamped inputs

2. Also for applications as 4-line-to-16-line decoders; 3-line-to-8-line decoders

3. All outputs are high for invalid input conditions

Logic Diagram



1. Can be used with a variety of display types, including LEDs and LCDs

2. Provides a straightforward method of decoding BCD inputs and displaying them on a 7-segment display

National Semiconductor was acquired by Texas Instruments (TI) on September 23, 2011.

Other data sheets are available within the file: 54LS42, 54LS42DMQB, 54LS42FMQB, DM54LS42

74LS42 Datasheet PDF

74LS42 pdf