Low-current ripple LED driver by two-phase driving approach

A two-phase driving approach for light-emitting diode (LED) power supply is proposed. The approach uses two rectangular current sources working complementarily to supply a constant current to the LED string so that the output current can contain very low ripple even without the use of any electrolytic capacitor in the driver circuit. A dual asymmetrical half-bridge converter with power factor correction is used to realise the approach. A 60 W prototype is built and tested to validate the idea.