74LVC138AD,112

Introduction

The 74LVC138AD,112 is an integrated logic signal switch/multiplexer/decoder designed to be used in a wide range of applications. Its wide operating voltage range of 1.5V to 5.5V allows it to be used in a variety of digital circuits, such as in microprocessors, computer buses, and communications. This device is particularly well suited for interfacing digital systems operating at different voltage levels.

Application Field

The 74LVC138AD,112 is used in applications that require the selection of one out of 8 active high or low input logic signals. It is commonly used in data multiplexing and memory address decoding. It can also be used to interface devices with different voltage levels, to amplify weak digital signals, and to reduce signals to a single line that are generated by several sources. Additionally, the device can be used for demultiplexing, as it can store one bit of informations and can be used in control circuit logic applications.

Working Principle

The 74LVC138AD,112 consists of two main components: a decoder and a multiplexer. The decoder is used to decode binary codes on to two active-low outputs, A and B. The multiplexer has four active-high select inputs, S0-S3, that can be used to select one of the 8 active inputs, I0-I7. It also has an active-high output, Y, which outputs the state of the selected input.

When an active low level input is applied to the S0-S3 select inputs, a positive logic is created. The positive logic is then used to enable the binary decoder, allowing it to decode the binary input. The decoder then uses the binary input to output either a 1 or 0 to output A and B. For example, if the binary number is 01, the decoder will output A=1 and B=0.

The multiplexer then uses the output from the decoder to select one of the 8 active input signals, and will output the state of the selected input. For example, if the decoder output is A=1, B=0, then the multiplexer will select and output the state of I1. If the decoder output is A=0, B=0, then the multiplexer will select and output the state of I0. This process is repeated until all 8 inputs have been selected.

Conclusion

The 74LVC138AD,112 integrated logic signal switch/multiplexer/decoder can be used in a wide variety of digital applications, especially ones that require the selection of one out of 8 active high or low input signals. Its wide operating voltage range allows it to be used in a variety of systems, and its two main components, decoder and multiplexer, are capable of decoding binary codes and selecting a single input from 8 available inputs.