Dimmable White LED Driver with Adaptive Voltage Feedback Control

An LED driver composed of a boost converter and dimmable current regulators with adaptive voltage feedback control (AVFC) is proposed. The AVFC is fulfilled with two diodes, one integrator, and one subtractor to sense the voltage variation among the current regulators and then to generate an adaptive reference voltage. According to the reference voltage, the output voltage of the boost converter is automatically regulated, so as to keep a minimum voltage on the current regulator and maintain the required LED-string current. A prototype driver implemented with 0.35-mu m 2P4M CMOS process validates the proposed technique. The simulation result shows that the output voltage of the boost converter is dynamically adjusted to compensate for the voltage alteration on the current regulators. out