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

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.