9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and

TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

9.1 Application Information

The SN74HCS157-Q1 is a quadruple 2-to-1 data selector/multiplexer. This application shows an example of

using the device with all required connections to switch a 4-bit data bus between two source devices.

9.2 Typical Application

System

Controller

A/B

G

GND

2:1

Mux

1B

1A

Device 0

Device 1

0.1…F

4Y

D0A

D0B

D0C

D0D

D1A

D1B

D1C

D1D

DXA

DXB

2:1

Mux

2:1

Mux

2:1

Mux

2B

2A

3B

3A

4B

4A

3Y

2Y

1Y

DXC

DXD

D0A

D0B

D0C

D0D

D1A

D1B

D1C

D1D

Figure 9-1. Typical application block diagram

9.2.1 Design Requirements

9.2.1.1 Power Considerations

Ensure the desired supply voltage is within the range specified in the Recommended Operating Conditions. The

supply voltage sets the device's electrical characteristics as described in the Electrical Characteristics.

The positive voltage supply must be capable of sourcing current equal to the total current to be sourced by all

and any transient current required for switching. The logic device can only source as much current as is provided

Absolute Maximum Ratings.

The ground must be capable of sinking current equal to the total current to be sunk by all outputs of the

current required for switching. The logic device can only sink as much current as can be sunk into its ground

connection. Be sure not to exceed the maximum total current through GND listed in the Absolute Maximum

Ratings.

The SN74HCS157-Q1 can drive a load with a total capacitance less than or equal to 50 pF while still meeting

all of the datasheet specifications. Larger capacitive loads can be applied, however it is not recommended to

exceed 50 pF.

the output voltage in the equation is defined as the difference between the measured output voltage and the

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SN74HCS157-Q1

SCLS820A – AUGUST 2020 – REVISED DECEMBER 2021

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