The number and type of capacitors in LED power supply vary depending on power supply design, power level and topology (such as flyback, LLC, Buck, etc.), but usually include the following types of capacitors:
1. Input side capacitor
X capacitor (safety capacitor):
Used to suppress differential mode interference (bridged between L-N lines), usually 1~2 pieces (metal film capacitor, capacity is about 0.1~1μF).
Electrolytic capacitor (high voltage filtering):
Used to smooth the DC high voltage (such as 400V) after rectification, the capacity is usually 10~100μF (depending on power requirements), the number is 1~2 pieces.
Y capacitor (safety capacitor):
Used to suppress common mode interference (bridged between L/GND or N/GND), usually 2~4 pieces (smaller capacity, about 1~10nF).
2. Output side capacitors
Electrolytic capacitors (low voltage filtering):
Used to stabilize output voltage (such as 12V/24V/48V), the capacity is usually 100~2000μF, the number is 1~4 (depending on the output current and ripple requirements).
Solid capacitors or ceramic capacitors:
High frequency filtering or transient response compensation, the capacity is small (such as 10~100μF), the number is several.
3. Control circuit capacitors
IC power supply capacitors:
Provide stable voltage for control chips (such as PWM ICs), usually 1~2 (ceramic capacitors or electrolytic capacitors, capacity 0.1~10μF).
Feedback loop capacitors:
Used to adjust loop stability, the capacity is small (such as 1~100nF), the number is 1~2.
4. Other capacitors
Resonant capacitors (LLC topology):
Used for resonant networks, the number is 1~2 (film capacitors or ceramic capacitors, the capacity is tens of nF~μF level).
Snubber circuit:
Notes
Electrolytic capacitors have a short lifespan: they are easy to dry out at high temperatures. It is recommended to choose 105℃ or 130℃ temperature-resistant and long-life models (such as more than 5,000 hours). you can buy 130℃ temperature-resistant from http://www.benweilight.com
Miniaturization design trend: high power density power supplies may use solid capacitors instead of electrolytic capacitors to reduce volume.
Safety requirements: X/Y capacitors must comply with safety standards (such as UL/CB certification) and cannot be replaced at will.
For example, a 20W LED driver may use a total of 5~10 capacitors, while a high-power (such as 200W) power supply may use more than 15. Please refer to the circuit design for details. you can visit http://www.benweilight.com for high quality LED driver lamp
