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Fixed 3.3 V LDO regulator

LM1117-3.3 Working Principle

Learn how LM1117-3.3 works with an illustrated explanation and practical readings.

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LM1117-3.3 at a glance

Follow the labeled connections and functional stages

LM1117-3.3 working principle: illustrated functional stages, basic circuit and connections
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How it works

3 stages · Explore one step at a time

Step 1 / 3

Compare and regulate

A reference and internal feedback network set the fixed 3.3 V output. The amplifier adjusts the pass stage as input or load changes.

Step 2 / 3

Stabilize the feedback loop

The output capacitor is required, not merely decorative bypassing. Select its capacitance and ESR for the manufacturer’s operating conditions.

Step 3 / 3

Account for power loss

The voltage dropped across the pass stage produces heat. Ground current adds another loss term, and the package needs a suitable thermal path.

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