High efficiency LED driver circuit diagram

This constant current output circuit is ideal for driving LEDs . The high output voltage supports a string of LEDs, eliminating the need to consider dividing current between LEDs and providing protection from load disconnect, overload, short circuit and overheating conditions. The efficiency of this circuit is very high (greater than 90%) in the entire operating voltage range. It has the advantages of being small, lightweight, low cost, and requiring a small number of components. It can meet the conducted EMI limit of EN55022B, and the EMI margin is greater than 10dBuV.

This circuit uses a LinkSwitch-TN device in a low-side buck converter configuration to provide 130mA constant current and 70V DC output voltage from an AC input voltage of 90 to 132V. This power supply is very suitable for driving LEDs that must be driven by constant current rather than constant voltage. Fuse FU1 provides protection in the event of a severe fault, and capacitor C1 and common mode choke L1 reduce conducted EMI . Diodes VD1 ~ VD4 provide full-wave rectification, and high-voltage capacitor C2 maintains a stable DC bus voltage.