LM7818CT

Introduction

The LM7818CT is a linear voltage regulator, a kind of three-terminal positive voltage regulator. It is designed to supply a fixed output voltage with an output current up to 1A. This device is specially designed for low voltage, high output current applications where the difference between the input voltage and output voltage is 6V or less. The LM7818CT can also operate with a wide range of input voltages.

This article will focus on the application field and working principle of the LM7818CT.

Application Field

LM7818CT can be used in low voltage, high output current power supplies. It is well-suited for applications such as:

• AC/DC Adapters
• Battery Management Systems
• Low voltage microprocessor supply
• Motor well integrated systems
• Digital audio systems
• DC-DC converters/linear regulators/switching regulators

The LM7818CTis a perfect choice for designers requiring a realiable, cost- effective solution in an very small, low-power-consuming package.

Working Principle

The LM7818CT is an linear regulator. Linear regulators are three-terminal voltage regulators which operate on the principle of dissipating excess power from their output to ground through an adjustable internal resistance. The LM7818CT specifically is a positive linear regulator, meaning it controlls the output voltage to a value greater than or equal to its input voltage.

The LM7818CT is designed to source current rather than sink current. This means that the output is at a higher voltage than the input. The current through the pass transistor will be equal to the output current. Since the device is designed to handle a maximum current rating of 1A, the transistor is put through a constant drain–source voltage with a maximum current of 1A. As the current increases, the voltage will be regulated to its designated regulated output voltage.

The LM7818CT uses two external components which allow it to regulate the output voltage. The first component is an error amplifier (which is integrated into the device), and the second component is a feedback resistor divider. The error amplifier is a high-precision amplifier which compares the output voltage to the reference voltage, and then uses this output to control the pass transistor. The feedback resistor dividers create a voltage, which is a fraction of the regulated output voltage. The output of the amplifier is compared to the divided voltage, and if the output voltage is too low, the error amplifier increases the voltage of the pass transistor.

Conclusion

The LM7818CT is a linear voltage regulator specially designed for low voltage, high output current applications. It is designed to source current, and has two external components which allow it to regulate the output voltage. This device can be used in a variety of low voltage applications such as AC/DC adapters and digital audio systems, making it a perfect choice for many design and application requirements.