Low-dropout regulators, commonly known as LDOs, are used extensively in a wide variety of electronic applications across many different industries. An LDO is generally perceived as a simple and inexpensive way to regulate and control an output voltage that is delivered from a higher input voltage supply. However, cost and simplicity are not the only reason for their widespread use. In fact, today’s systems are getting more complex, noise sensitive and power hungry with every new design. The widespread use of
switching power supplies at all power levels means that designers must spend more time avoiding noise coupling and interference, while improving system efficiency, so cost and simplicity cannot be the only driver.
For most applications, a datasheet’s specifications of basic parameters are clear and easy to understand. Unfortunately, datasheets do not list the parameters for every possible circuit condition. Therefore, to make the best use of an LDO, it is necessary to understand the key performance parameters and their impact on given loads. Designers will need to determine whether the LDO is suitable for a specific load by closely
analyzing the surrounding circuit conditions.
This article examines the key performance parameters of LDOs and their impact on delivering clean output voltage to the various devices inside an electronic system.
We’ll also discuss the factors a designer must consider to optimize a system,
especially at higher current levels.
How LDOs are Used in Applications
In most applications, LDOs are primarily used to isolate a sensitive load from a noisy power source. Unlike switching regulators, linear regulators dissipate power in the pass transistor or the MOSFET that is used to regulate and maintain the output voltage to the required accuracy. As a result, an LDO’s power dissipation can be a significant disadvantage in terms of efficiency and can cause thermal issues. Therefore, it is important for designers to minimize LDO power dissipation to boost system efficiency