A 16–28-W 92.8%-Efficiency Monolithic Quasi-Resonant LED Driver With Constant-Duty-Ratio Frequency Regulator

This brief presents a monolithic high-voltage light-emitting diode (LED) driver for lighting applications. The LED driver is able to operate at high switching frequency because large switching loss is eliminated by zero-voltage switching. Inductor values are therefore reduced. A constant-duty-ratio frequency regulator (CDFR) is proposed to regulate the LED current, and the small signal characteristics of the proposed LED driver with CDFR are analyzed. The proposed design, including the controller and power transistor, was fabricated in MagnaChip 0.35-μm 700-V bipolar-CMOSLDMOS process. The LED driver with 2 × 3.9 μH inductors switches at around 5.4 MHz and powers up 16-28 1-W LEDs. Experimental results show that the LED driver achieves peak efficiency of 92.8% within the input voltage range of 55-120 V.