Linear Voltage Regulators: An Essential Component for Power Supply...

Linear Voltage Regulators: An Essential Component for Power Supply Circuits

Posted 2025-02-27 04:41:43

What are Linear Voltage Regulators?
A linear voltage regulator is a simple yet versatile electronic component that regulates the output voltage in a circuit based on the principle of linear control. It takes an input voltage, usually higher than the desired output, and produces a lower, stable output voltage regardless of changes in load current or input voltage.

Working Principle
At its core, a linear voltage regulator contains three essential elements - an input terminal, output terminal, and an adjustable reference terminal. It operates by comparing the output voltage to an internal fixed reference voltage and continuously adjusting the control element i.e the pass transistor to maintain the output at the required level. Whenever the output voltage drops due to an increase in load current, the pass transistor conducts more to bring up the voltage again. This feedback loop action enables the linear regulator to keep the output steady within tight tolerances.

Types of Linear Voltage Regulators
There are various types of linear regulators based on the package, reference type and adjustments options:

- Fixed Voltage Regulators: As the name suggests, these Linear Voltage Regulators provide a fixed output voltage specified by the part number e.g. 5V, 12V etc. The reference voltage is internally set during manufacturing.

- Adjustable Voltage Regulators: These regulators have an adjustable reference pin/screw which allows setting the output voltage over a range by varying the reference voltage. LM723, LM338 are commonly used adjustable regulators.

- Low Drop Out (LDO) Regulators: Suitable for applications requiring high-efficiency at low output-input voltage differences of <1V. They exhibit lower quiescent current and can operate at higher temperatures.

- Special Function Regulators: Include current limiters, tracking regulators, reverse polarity protection, short circuit protection etc. Example is LP2950 which has overcurrent protection.