HD74HC251

HD74HC251 1 of 8 Data Selectors/Multiplexers (with 3-state outputs) Description This multiplexer features both true (Y) and complement (W) outputs as well as a strobe input. The strobe must be at a low logic level to enable this device. When the strobe input is high, both outputs are in the high impedance state. When enabled, address information on the data select inputs determines which data input is routed to the Y and W outputs. Features High Speed Operation: tpd (A, B, C to Y) = 20 ns typ (C L = 50 pF) 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) HD74HC251 Function Table Inputs Select C X L L L L H H H H B X L L H H L L H H A X L H L H L H L H Strobe S H L L L L L L L L Outputs Y Z D0 D1 D2 D3 D4 D5 D6 D7 W Z D0 D1 D2 D3 D4 D5 D6 D7 Notes 1. H: high level, L: low level, X: irrelevant 2. Z; high impedcance (off-state) 3. D0 through D7; the level of the respective D input. Pin Arrangement 3 2 Data inputs 1 0 Y Outputs W Strobe GND 1 2 3 4 5 6 7 8 D2 D1 D0 Y W S C D3 D4 D5 D6 D7 A B 16 VCC 15 4 14 5 Data inputs 13 6 12 7 11 A 10 B 9 C Data select (Top view) 2 HD74HC251 Block Diagram A B C D0 D1 D2 Strobe D3 VCC D4 Y D5 VCC D6 W D7 3 HD74HC251 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 ±5.0 ±1.0 40 µA µA µA I OL = 4 mA I OL = ...