CD74HC257M集成电路（IC）的信号开关多路复用器解码器规格书PDF中文资料

CD74HC257M属于集成电路（IC）的信号开关多路复用器解码器。由德州仪器制造生产的CD74HC257M信号开关，多路复用器，解码器逻辑型信号开关、多路复用器和编码器 IC 可用于对以数字格式表示数据的电信号进行路由和选择。这些器件与设计用于模拟信号的类似产品有所不同，它们保留的信息表示为两个电状态之一，而不是两个外部界限内的无穷变化量。

特性 Features

• Buffered Inputs

• Typical Propagation Delay ( In to Output ) = 12ns at

VCC = 5V, CL = 15pF, TA = 25oC

• Fanout (Over Temperature Range)

- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads

- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads

• Wide Operating Temperature Range . . . -55oC to 125oC

• Balanced Propagation Delay and Transition Times

• Significant Power Reduction Compared to LSTTL

Logic ICs

• HC Types

- 2V to 6V Operation

- High Noise Immunity: NIL = 30%, NIH = 30% of VCC

at VCC = 5V

• HCT Types

- 4.5V to 5.5V Operation

- Direct LSTTL Input Logic Compatibility,

VIL= 0.8V (Max), VIH = 2V (Min)

- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

描述 Description

The ’HC257 and ’HCT257 are quad 2-input multiplexers

which select four bits of data from two sources under the

control of a common Select Input (S). The Output Enable

input (OE) is active LOW. When OE is HIGH, all of the outputs

(1Y-4Y) are in the high impedance state regardless of

all other input conditions.

Moving data from two groups of registers to four common

output buses is a common use of the 257. The state of the

Select input determines the particular register from which

the data comes. It can also be used as a function generator.