特性 Features

? Common Select Inputs

? Separate Enable Inputs

? Buffered inputs and Outputs

? 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 ’HC157, ’HCT157, ’HC158, and ’HCT158 are quad 2-

input multiplexers which select four bits of data from two

sources under the control of a common Select input (S). The

Enable input (E) is active Low. When (E) is High, all of the

outputs in the 158, the inverting type, (1Y-4Y) are forced

High and in the 157, the non-inverting type, all of the outputs

(1Y-4Y) are forced Low, regardless of all other input

conditions.

Moving data from two groups of registers to four common

output buses is a common use of these devices. The state of

the Select input determines the particular register from

which the data comes. They can also be used as function

generators.