HD74HC138

HD74HC138 3-to-8-line Decoder/Demultiplexer Description The HD74HC138 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 High Speed Operation: tpd (A, B, C to Y) = 16.5 ns typ (CL = 50 pF) High Output Current: Fanout of 10 LSTTL Loads Wide Operating Voltage: VCC = 2 V 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 H H H L H H H H H H H Y1 H H H H L H H H H H H Y2 H H H H H L H H H H H Y3 H H H H H H L H H H H Y4 H H H H H H H L H H H Y5 H H H H H H H H L H H Y6 H H H H H H H H H L H Y7 H H H H H H H H H H L HD74HC138 Pin Arrangement A 1 Select Inputs B 2 C 3 G2A 4 Enable Inputs G2B 5 G1 6 Output Y7 7 GND 8 (Top view) B C G2A G2B G1 Y7 A Y0 Y1 Y2 Y3 Y4 Y6 Y5 16 VCC 15 Y0 14 Y1 13 Y2 12 Y3 11 Y4 10 Y5 9 Y6 Outputs 2 HD74HC138 DC Characteristics Ta = 25°C Item Input voltage Symbol VIH Ta = –40 to +85°C Max — — — 0.5 1.35 1.8 — — — — — 0.1 0.1 0.1 0.33 0.33 ±1.0 40 µA µA I OL = 4 mA I OL = 5.2 mA Vin = VCC or GND Vin = VCC or GND, Iout = 0 µA V I OH = –4 mA I OH = –5.2 mA Vin = VIH or VIL I OL = 20 µA V Vin...