器件名称:
74HC257
功能描述:
Quad. 2-to-1-line Data Selectors/Multiplexers(with noninverted 3-state outputs)
文件大小:
52.59KB 共9页
简 介:
HD74HC257 Quad. 2-to-1-line Data Selectors/Multiplexers (with noninverted 3-state outputs) Description The large output drive capability coupled with the 3-state feature make this device ideal for interfacing with bus lines in a bus organized system. When the output control input line is taken high, the outputs of all four multiplexers are sent into a high impedance state. When the output control line is low, the select input chooses whether the A or B input is used. Features High Speed Operation: tpd (Data to Y) = 10.5 ns typ (CL = 50 pF) High Output Current: Fanout of 15 LSTTL Loads Wide Operating Voltage: VCC = 2 to 6 V Low Input Current: 1 A max Low Quiescent Supply Current: ICC (static) = 4 A max (Ta = 25°C) Function Table Inputs Output Control L L L L H Select L L H H X A L H X X X B X X L H X Outputs Y L H L H High impedance Notes H: high level, L: low level, X: irrelevant HD74HC257 Pin Arrangement Select 1A 1B 1Y 2A 2B 2Y GND 1 2 3 4 5 6 7 8 (Top view) 1A 1B 1Y 2A 2B 2Y 3Y S OC 4A 4B 4Y 3A 3B 16 VCC 15 Output control 14 4A 13 4B 12 4Y 11 3A 10 3B 9 3Y Absolute Maximum Ratings Item Supply voltage range Input voltage Output voltage DC current drain per pin DC current drain per VCC, GND DC input diode current DC output diode current Power dissipation per package Storage temperature Symbol VCC VIN VOUT I OUT I CC, I GND I IK I OK PT Tstg Rating –0.5 to +7.0 –0.5 to VCC + 0.5 –0.5 to VCC + 0.5 ±35 ±75 ±20 ±20 500 –65 to +150 Unit V V V mA mA mA mA mW °C 2 ……
