74LS42 BCD to Decimal Decoder


The 74LS series of integrated circuits (ICs) was one of the most popular logic families of transistor-transistor logic (TTL) logic chips. 74LS series is a bipolar, low-power Schottky IC. 74LS42 BCD to Decimal Decoder monolithic 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
valid input logic ensures that all outputs remain off for all invalid input conditions.

74LS42 Features

  • Multipurpose Decoder
  • Mutually Exclusive Outputs
  • Demultiplexing Capability
  • Operating Temperature up to 70°C
  • Standard TTL Switching Voltages

74LS42 Specifications

Supply Voltage4.75 – 5.25Vdc
Maximum Clock Frequency40Mhz
Power Dissipation2mW/gate @100kHz
Minimum Output Current8mA
Propagation Delay10nS
Fan Out (TTL Loads)20

74LS42 Pinout Diagram

74LS42 Pin Description

Pin NoPin NameDescription
10Decoder Output Bit 0
21 Decoder Output Bit 1
32 Decoder Output Bit 2
43 Decoder Output Bit 3
54 Decoder Output Bit 4
65 Decoder Output Bit 5
76 Decoder Output Bit 6
97′ Decoder Output Bit 7
108′ Decoder Output Bit 8
119′ Decoder Output Bit 9
12A3 Binary Input A3
13A2 Binary Input A2
14A1 Binary Input A1
15A0 Binary Input A0
16VCCPositive Supply

74LS42 Circuit


  • It is used in code conversions
  • It may also be used for data distribution i.e. demultiplexing.

74LS42 Alternative Equivalent

Download 74LS42 BCD to Decimal Decoder Datasheet from the link given below.