Special for switching power supply

Aluminum electrolytic capacitors are also widely used in switching power supplies, especially in filtering and energy storage. Choosing the right aluminum electrolytic capacitor is very important to improve the performance and stability of the switching power supply. The following are some key factors and suggestions for selecting aluminum electrolytic capacitors in switching power supplies:

Key factors

capacitance: Select the appropriate capacitance according to the circuit requirements. Generally speaking, the input filter capacitor needs a large capacity (hundreds of microFarads to thousands of microFarads), and the output filter capacitor is selected according to the load demand.

Withstand voltage value: Choose a capacitor whose withstand voltage is 20-30% higher than the actual working voltage to ensure safety and reliability.

Low ESR (equivalent series resistance)Low ESR capacitors reduce power ripple and noise, improving power efficiency and stability.

High ripple current capability: The capacitor in the switching power supply needs to handle large current fluctuations, and the capacitor with high ripple current capability can withstand these fluctuations without affecting performance.

Temperature range: Choose a capacitor with a wide temperature range (such as -40°C to 105°C) to ensure stable operation in various environments.

Application example

Input filter capacitor: Selecting a low ESR capacitor of 3300 µF/250V can significantly reduce high-frequency ripple and noise at the input.

output filter capacitor: Select 470 µF/50V capacitor, with high ripple current capability and low ESR characteristics, can improve the stability of the output voltage.

Precautions

• Service life: Choose long-life capacitors (such as 2000 hours or more), especially in high temperature environments.
• Installation method: Select the appropriate pin type (axial, radial or patch) according to the board layout.
• parallel use: Sometimes multiple capacitors of smaller capacity can be used in parallel to reduce ESR and increase ripple current capability.