Automotive Catalog High Speed CMOS Logic 3-to-8 Line Decoder Demultiplexer Inverting and Non-Invert - CD74HC138-Q1


Automotive Catalog High Speed CMOS Logic 3-to-8 Line Decoder Demultiplexer Inverting and Non-Invert



The CD74HC138 is a high-speed silicon-gate CMOS decoder well suited to memory address decoding or data routing applications. This circuit features low power consumption usually associated with CMOS circuitry, yet has speeds comparable to low-power Schottky TTL logic. The circuit has three binary select inputs (A0, A1, and A2). If the device is enabled, these inputs determine which one of the eight normally high outputs of the HC138 will go low.

Two active-low and one active-high enables (E1, E2, and E3) are provided to ease the cascading of decoders. The decoder’s eight outputs can drive ten low-power Schottky TTL equivalent loads.


  • Qualified for Automotive Applications
  • Select One of Eight Data Outputs Active Low
  • I/O Port or Memory Selector
  • Three Enable Inputs to Simplify Cascading
  • Typical Propagation Delay of 13 ns at VCC = 5 V, CL = 15 pF, TA = 25°C
  • Fanout (Over Temperature Range)
    • Standard Outputs . . . 10 LSTTL Loads
    • Bus Driver Outputs . . . 15 LSTTL Loads
  • Balanced Propagation Delay and Transition Times
  • Significant Power Reduction Compared to LSTTL Logic ICs
  • 2-V to 6-V VCC Operation
  • High Noise Immunity; NIL or NIH = 30% of VCC, VCC = 5 V

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Parametrics Compare all products in Buffered Encoders and Decoders

Technology Family
VCC (Min) (V)
VCC (Max) (V)
Channels (#)
Voltage (Nom) (V)
F @ Nom Voltage (Max) (Mhz)
ICC @ Nom Voltage (Max) (mA)
tpd @ Nom Voltage (Max) (ns)
Output Drive (IOL/IOH) (Max) (mA)
Bits (#)
Operating Temperature Range (C)
CD74HC138-Q1 CD54HC138 CD74HC138
  Decoder/Demultiplexer    Decoder/Demultiplexer   
HC    HC    HC   
2    2    2   
6    6    6   
1    1    1   
28    28    28   
0.08    0.08    0.08   
30    30    30   
  3:8    3:8   
  Standard    Standard   
5.2/-5.2    5.2/-5.2    5.2/-5.2   
8    8    8   
Automotive    Military    Catalog   
-40 to 125    -55 to 125    -55 to 125   
16SOIC    16CDIP    16PDIP

Other qualified versions of CD74HC138-Q1

Version Part Number Definition
Military CD54HC138 QML certified for Military and Defense Applications
Catalog CD74HC138 TI's standard catalog product