onsemi Low Cost Universal AC Input LED Circuit Evaluation Board LED Driver for DBB08G-TM-E, MMBT3906LT1G, MMBT6520LT1G,

The UIC1WGEVB evaluation board showcases a simple, low cost, low part count chopper topology circuit. It is designed to safely operate with input voltages varying from 80 VAC to 280 VAC. ON Semiconductor CCRs are used to provide constant LED current and to protect LEDs from over-voltage conditions. This circuit uses active switching to change how the load is being driven. The LED load will either be driven from the capacitor, C1, discharging, or directly from the AC source. The CCR ensures a constant current through the LED throughout all modes of operation. The switching point of the circuit may be changed by varying the resistor, R1. Changing this switching point will change the amount of time the capacitor is charging. If a higher power output is desired a higher current CCR can be used and the switching point will need to be changed. A metal oxide varistor and fuse are designed into the circuit for surge protection purposes.