Analysis of the Function and Principle of Linear Voltage Regulator in Electronic Circuit

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Analysis of the Function and Principle of Linear Voltage Regulator in Electronic Circuit [Copy link]

Linear regulators are a type of power management device widely used in electronic circuits. Their main function is to convert unstable DC power (input) into a stable output voltage, and the output voltage is almost independent of the load current. Linear regulators can provide relatively stable power supply voltage with small ripple to various components in the circuit, thereby ensuring the normal operation of electronic equipment, household appliances, computers, etc.

1. Basic working principle of linear regulator

The basic working principle of a linear voltage regulator is to adjust the input voltage through a regulation circuit, remove noise, and then pass it to the output port of a stable voltage. Among them, the regulation circuit usually consists of two parts: a reference voltage source and an error amplifier. The reference voltage source provides a fixed reference voltage, and the error amplifier outputs an error voltage. By comparing these two signals, a control signal is generated to adjust the conduction state of the transistor or the regulation tube so that the output voltage remains stable.

Specifically, in a linear regulator, the conduction state of the regulating tube determines the voltage difference between the output voltage and the input voltage, and the error amplifier is an amplifier that generates an error signal based on this voltage difference. If the output voltage is lower than the set standard voltage value, if the regulator is required to increase the voltage, the control voltage will cause the transistor or regulating tube to be turned on for a longer time, and the output voltage will increase. Conversely, if the output voltage is higher than the standard voltage value, the conduction time will be reduced and the output voltage will decrease.

2. Characteristics of Linear Regulators

Linear regulators have the following characteristics:

Linear regulators can provide stable power supply voltage with low ripple, which can meet the power quality requirements of various circuits.

The output current of the linear regulator is almost unaffected by the load current, so it has high stability.

Linear regulators have low output resistance and noise, which makes them widely used in some application scenarios with high signal-to-noise ratio requirements.

Linear voltage regulators are easy to adjust and have high reliability, making them suitable for most electronic circuits with low power requirements.

The cost of linear regulators is low and they have a higher cost-performance ratio compared to other power management devices.

Although linear regulators have many advantages, they also have some disadvantages, such as high power consumption, low efficiency, high temperature rise, etc. Therefore, in some occasions that require low noise, low ripple, high efficiency, and high stability, other types of power management devices can be considered.

3. Common Linear Regulators

Common linear regulators include 78xx series, 79xx series and LM317. The following is a detailed introduction to these three linear regulators.

1.78xx series

The 78xx series linear regulator is a type of positive voltage regulator with a fixed output voltage, where xx represents the output voltage, such as the 7805 output voltage is 5V. This linear regulator is easy to use because it only requires a few external components to form a complete regulator circuit. The 78xx series linear regulator is one of the more commonly used linear regulators and is commonly found in the power supply circuits of various electronic devices.

2.79xx Series

The 79xx series linear regulator is a type of negative voltage regulator with a fixed output voltage, where xx represents the output voltage, such as the output voltage of 7905 is -5V. The characteristics of the 79xx series linear regulator are similar to those of the 78xx series linear regulator, except that the polarity of the output voltage is opposite. The 79xx series linear regulator is also one of the devices frequently used in electronic circuits.

3.LM317

LM317 is a linear voltage regulator with adjustable output voltage. It can provide a larger and wider voltage range than the 78xx series and 79xx series, and the output voltage value can be adjusted by adjusting external components. This linear voltage regulator is often used as a power supply voltage regulation circuit in a conventional electronic circuit.

As a power management device widely used in electronic circuits, linear regulators can stabilize unstable DC power supplies and provide power supply voltage for the normal operation of various electronic devices. Linear regulators have the characteristics of easy adjustment, low noise, low ripple, and low output resistance. They are suitable for most electronic circuits with low power requirements, such as electronic equipment, household appliances, computers, etc. At the same time, linear regulators also have some disadvantages, such as high power consumption, low efficiency, and high temperature rise. Therefore, when choosing to use a linear regulator, you need to choose the correct model according to the actual scenario to ensure that it can play its best role.

led2015

When designing, pay attention to the input and output voltage range, maximum output current, heat dissipation, and the selection of filter capacitors.

火辣西米秀

These chips are old enough.