HD74HCT238 3-to-8-line Decoder/Demultiplexer Description The HD74HCT238 has 3 binary select inputs (A, B, and C). If the device is enabled these inputs determined 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 • • • • • • LSTTL Output Logic Level Compatibility as well as CMOS Output Compatibility High Speed Operation: tpd (A, B, C to Y) = 18.5 ns typ (CL = 50 pF) High Output Current: Fanout of 10 LSTTL Loads Wide Operating Voltage: VCC = 4.5 to 5.5 V Low Input Current: 1 µA max Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C) HD74HCT238 Function Table Inputs Enable Select Outputs G1 G2A G2B C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 X X H X X X L L L L L L L L X H X X X X L L L L L L L L L X X X X X L L L L L L L L H L L L L L H L L L L L L L H L L L L H L H L L L L L L H L L L H L L L H L L L L L H L L L H H L L L H L L L L H L L H L L L L L L H L L L H L L H L H L L L L L H L L H L L H H L L L L L L L H L H L L H H H L L L L L L L H Pin Arrangement Select Inputs Enable Inputs Outputs A 1 16 VCC B 2 B C 3 G2A A Y0 15 Y0 C Y1 14 Y1 4 G2A Y2 13 Y2 G2B 5 G2B Y3 12 Y3 G1 6 G1 Y4 11 Y4 Y7 7 Y7 Y5 10 Y5 GND 8 Y6 9 (Top view) 2 Y6 Outputs HD74HCT238 Logic Diagram G1 G2B Y0 G2A Y1 A Y2 Y3 B Y4 C Y5 Y6 Y7 DC Characteristics Ta = –40 to +85°C Ta = 25°C Test Conditions Item Symbol Min Typ Max Min Max Unit VCC (V) Input voltage VIH 2.0 — — — V 4.5 to 5.5 VIL — — 0.8 — 0.8 V 4.5 to 5.5 VOH 4.4 — — 4.4 — V 4.5 Vin = VIH or VIL I OH = –20 µA 4.18 — — 4.13 — 4.5 I OH = –4 mA — — 0.1 — 0.1 — — 0.26 — 0.33 Output voltage VOL 2.0 V 4.5 Vin = VIH or VIL I OL = 20 µA 4.5 I OL = 4 mA Input current Iin — — ±0.1 — ±1.0 µA 5.5 Vin = VCC or GND Quiescent supply current I CC — — 4.0 — 40 µA 5.5 Vin = VCC or GND, Iout = 0 µA 3 HD74HCT238 AC Characteristics (CL = 50 pF, Input tr = tf = 6 ns) Ta = –40 to +85°C Ta = 25°C Test Conditions Min Typ Max Min Max Unit VCC (V) Propagation delay t PLH — 18 30 — 38 ns 4.5 time t PHL — 19 30 — 38 t PLH — 17 30 — 38 t PHL — 17 30 — 39 t PLH — 17 30 — 38 t PHL — 17 30 — 38 t PLH — 17 30 — 38 t PHL — 17 30 — 38 Output rise/fall time t TLH t THL — 5 15 — 19 ns 4.5 Input capacitance Cin — 5 10 — 10 pF — Item 4 Symbol A, B or C to Y 4.5 ns 4.5 G2A to Y 4.5 ns 4.5 G2B to Y 4.5 ns 4.5 4.5 G1 to Y Unit: mm 19.20 20.00 Max 1 7.40 Max 9 6.30 16 8 1.3 0.48 ± 0.10 2.54 Min 5.06 Max 2.54 ± 0.25 0.51 Min 1.11 Max 7.62 + 0.13 0.25 – 0.05 0° – 15° Hitachi Code JEDEC EIAJ Weight (reference value) DP-16 Conforms Conforms 1.07 g Unit: mm 10.06 10.5 Max 9 1 8 1.27 *0.42 ± 0.08 0.40 ± 0.06 0.10 ± 0.10 0.80 Max *0.22 ± 0.05 0.20 ± 0.04 2.20 Max 5.5 16 0.20 7.80 +– 0.30 1.15 0° – 8° 0.70 ± 0.20 0.15 0.12 M *Dimension including the plating thickness Base material dimension Hitachi Code JEDEC EIAJ Weight (reference value) FP-16DA — Conforms 0.24 g Unit: mm 9.9 10.3 Max 9 1 8 0.635 Max *0.42 ± 0.08 0.40 ± 0.06 0.15 *0.22 ± 0.03 0.20 ± 0.03 1.27 0.11 0.14 +– 0.04 1.75 Max 3.95 16 0.10 6.10 +– 0.30 1.08 0° – 8° 0.67 0.60 +– 0.20 0.25 M *Dimension including the plating thickness Base material dimension Hitachi Code JEDEC EIAJ Weight (reference value) FP-16DN Conforms Conforms 0.15 g Cautions 1. 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