A Wide-Input-Range Efficiency-Enhanced Synchronous Integrated LED Driver With Adaptive Resonant Timing Control

A wide-input-range DC-DC-based dimmable LED driver is presented in this paper. The proposed LED driver can be automatically configured to operate in the soft-switching mode under the high-voltage condition in order to minimize the converter's dominant switching power loss. Adaptive resonant timing control is developed to enable proper dead-time generation for on-chip high-voltage power FETs in both hard- and soft-switching modes under different input and output voltages for the power loss minimization. In the proposed LED driver, two low-power body-diode-based zero-voltage detectors and an adaptive resonant timing emulator are also proposed for providing accurate and high-speed zero-voltage switching (ZVS) detection of both power FETs, and achieving optimal quasi-ZVS condition, respectively. Implemented in a 0.5 μm HV CMOS process, the proposed buck-based LED driver can support an input voltage range from 5 V to 115 V and up to 25 series-connected highbrightness LEDs with the maximum output power of 25 W. The LED driver can operate up to 1.6 MHz in the soft-switching mode and 2.2 MHz in the hard-switching mode for providing the peak power efficiencies of 94.4% and 93.6%, respectively. Compared with the state-of-the-art counterparts, this work is the only integrated DC-DC-based dimmable LED driver to demonstrate auto-configurable hard- and soft-switching capability achieving high power efficiency and current accuracy over the widest input voltage range and the largest number of series-connected output LEDs.