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When is the inductor added to the LDO output?

Hardware design
November 26, 2020 by Jessica 1669

The picture shows a demo board of ti, but the LDO output part is connected to a 10mH inductor. When do I need to add it? What is the purpose of adding such a large inductor?

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Samantha Posted on November 26, 2020

1. Here should be LC filter composed of inductor and capacitor. The size of inductance and capacitance determines the frequency of filtering.

2. Your left side is battery output, so you need to add a filter circuit. The effect of using magnetic beads should not be so good.

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Ella Posted on November 26, 2020

Inductance is added when the input voltage changes greatly, but now LDOs are rarely added.

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Sarah Posted on November 26, 2020

The first thing following the LDO is definitely a large capacitor, 1uF or 10uF. Whether to add an inductor after that depends on the designer's thought. But the first thing that follows must be the capacitor and not 0.1uF. . . Generally for 20M circuit boards and low voltage (for example, 3.3V 1.8V 1.2V), connect a 1uF capacitor to the back of the LDO and then a 0.1uF and then a 0.01uF capacitor. Generally, there is no need to add inductance to this design.

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Angel Posted on November 26, 2020

LDO output plus inductor, this kind of usage is rare.

It is often not to filter the ripple of the LDO output, but to filter the impact of the noise of the back-end circuit on the LDO, or when the LDO is used for multi-channel power supply (such as analog power supply and digital power supply), filter the noise in the digital power supply to avoid interference Simulate the influence of power supply.

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