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3-to-8 Line Decoder Demultiplexer

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The 74HC138 is a high speed CMOS device. The device accepts a three bit binary weighted address on input pins A0, A1 and A2 and when enab°C will produce one active low output with the remaing seven being high. There are two active LOW enable inputs 1 and 2, and one active HIGH enable input E3. The disab°C device state results in all outputs being high. The enable state occurs with 1 and 2 asserted low and E3 asserted high. The multiple enable lines allow for the parallel expansion of decoders to create 4-to-16 line versions with no additional parts and 5-to-32 versions with the addition of a single inverter.


  • Memory chip select decoding
  • Demultiplexing
  • Single line peripheral control
  • Allow simple serial bit streams from a microcontroller to control as many peripheral lines as needed
  • Product Specifications

    Product Parameters

    Number of Gates -
    Family HC
    VCC Min (V) 2 V
    VCC Maximum Rating 6 V
    tpd max @ (1.5V) - ns
    tpd max @ 1.8V (ns) - ns
    tpd max @ 2.5V (ns) 190 ns
    tpd max @ 3.3V (ns) - ns
    tpd max @ 5.0V (ns) 38 ns
    Input/ Output Current 4
    Description 3-to-8 Line Decoder Demultiplexer
    Output Type Push-Pull

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    Orderable Part Number Buy from Distributor / Contact Sales Request Samples


    Authorized Distributor Quantity Inventory Date Countries/Regions Buy Online
    RS Components - France 250 10/4/2022 France Buy Now
    RS Components - Germany 150 10/4/2022 Germany Buy Now
    RS Components - Spain 225 10/4/2022 Spain Contact Sales
    RS Components - Spain 1450 10/4/2022 Spain Contact Sales
    RS Components - UK 225 10/4/2022 England Buy Now
    RS Components - UK 1450 10/4/2022 England Buy Now
    RS Components S.p.A - Italy 400 10/4/2022 Italy Buy Now
    Request Sample


    Authorized Distributor Quantity Inventory Date Countries/Regions Buy Online
    Mouser Electronics Inc. 285 10/4/2022 South America, North America, Asia, Europe, Middle East Buy Now
    Request Sample

    Product Change Notices (PCNs)

    A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

    PCN # Issue Date Implementation Date Subject
    PCN-2512 2021-04-16 2021-07-16 Qualified Additional Assembly & Test (A/T) Site