HD74HC238
HD74HC238 is 3-to-8-line Decoder/Demultiplexer manufactured by Hitachi Semiconductor.
Description
The HD74HC238 has 3 binary select inputs (A, B and C). If the device is enabled these inputs determine which one of the eight normally high outputs will go low. Two active low and one active high enables (G1, G2A and G2B) are provided to ease the cascading of decoders.
Features
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- High Speed Operation: tpd (Data to Y) = 15 ns typ (CL = 50 p F) High Output Current: Fanout of 10 LSTTL Loads Wide Operating Voltage: VCC = 2 to 6 V Low Input Current: 1 µA max Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)
Function Table
Inputs Enable G1 X X L H H H H H H H H G2A X H X L L L L L L L L G2B H X X L L L L L L L L Select C X X X L L L L H H H H B X X X L L H H L L H H A X X X L H L H L H L H Outputs Y0 L L L H L L L L L L L Y1 L L L L H L L L L L L Y2 L L L L L H L L L L L Y3 L L L L L L H L L L L Y4 L L L L L L L H L L L Y5 L L L L L L L L H L L Y6 L L L L L L L L L H L Y7 L L L L L L L L L L H
Pin Arrangement
A Select Inputs B C G2A Enable Inputs G2B G1 Output Y7 GND
1 2 3 4 5 6 7 8 B C G2A G2B G1 Y7 Y6 A Y0 Y1 Y2 Y3 Y4 Y5
16 VCC 15 Y0 14 Y1 13 Y2 12 Y3 11 Y4 10 Y5 9 Y6 Outputs
(Top view)
Logic Diagram
G1 G2B G2A Y1 Y0
Y2
Y3
Y4
Y5
Y6
Y7
DC Characteristics
Ta = 25°C Item Input voltage Symbol VIH Ta =
- 40 to +85°C Max
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- 0.5 1.35 1.8
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- 0.1 0.1 0.1 0.33 0.33 ±1.0 40 µA µA I OL = 4 m A I OL = 5.2 m A Vin = VCC or GND Vin = VCC or GND, Iout = 0 µA V I OH =
- 4 m A I OH =
- 5.2 m A Vin = VIH or VIL I OL = 20 µA V Vin = VIH or VIL I OH =
- 20 µA V Unit V Test Conditions
VCC (V) Min Typ Max Min 2.0 4.5 6.0 1.5
- 3.15
- 4.2
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