Among all passive components, aluminum electrolytic capacitors have one of the highest failure rates. Selecting aluminum electrolytic capacitors involves considering several important parameters. When designing, it is essential to refer to relevant product manuals, carefully determine the appropriate model, and conduct actual tests.

Capacitance, Rated Operating Voltage, and External Dimensions:
These are the fundamental parameters to consider first. Larger capacitors are needed in applications where the current changes rapidly. However, increasing capacitance also increases cost, volume, and charging time. Ensure that the operating voltage has an adequate margin, generally more than 15%, to reduce internal resistance, leakage current, loss angle, and to extend the capacitor’s life.

Dielectric Loss, Leakage Current, ESR, and Ripple Current:
The loss angle reflects the capacitor’s efficiency; a larger loss angle indicates greater loss. Capacitors with large loss angles are unsuitable for high-frequency conditions, and aluminum electrolytic capacitors typically have relatively high loss angles. Leakage current generally increases with temperature and voltage; higher capacitance also results in greater leakage current. Lowering the operating voltage can reduce leakage current. ESR and ripple current also impact the performance of aluminum electrolytic capacitors.

Impedance-Frequency Characteristics and Life:
The impedance of a capacitor increases with frequency. Capacitors with lower equivalent impedance are better at filtering high-frequency spike signals. The capacitor’s life is influenced by several factors, with temperature being the most significant. Typically, the life of aluminum electrolytic capacitors is halved for every 10°C increase in operating temperature. Therefore, a capacitor rated for 2000 hours may not last longer than 1000 hours under higher temperatures.