Application Key Points of Electrolytic Capacitors in Power Supply Design​

1. Core Function of Electrolytic Capacitors

Acts as the "energy reservoir" of a circuit.

Commonly used in inverters and DC-DC converters.

Provides higher capacitance (e.g., 220μF) compared to other capacitor types.

2. Key Parameters for Selection

Capacitance value: Determines low-frequency filtering performance.

ESR (Equivalent Series Resistance): Affects high-frequency losses and system stability.

Temperature impact: Higher temperatures reduce ESR but shorten lifespan.

3. Critical Design Considerations

Thermal loop effect:

Minimize the current loop area between the capacitor and the switching transistor.

Recommended distance: ≤3cm.

Larger loops can cause EMI issues.

4. Practical Tips

Aluminum-shell electrolytic capacitors provide built-in EMI shielding.

Reduces high-frequency radiation by 3-5dB.

More cost-effective than film capacitors.

Summary

Prioritize capacitance and ESR.

Layout optimization is more critical than parameter selection.

Leverage the shielding benefits of aluminum-shell capacitors.