A 5–115V efficiency-enhanced synchronous LED driver with adaptive resonant timing control

Abstract

A wide-input-range (5-115V) DC-DC based synchronous LED driver is presented in this paper. The proposed LED driver can automatically operate in the soft-switching mode to minimize the converter's switching loss in the HV condition. An adaptive resonate timing control (ARTC) is developed to generate optimal dead-time for establishing zero-voltage switching of both high- and low-side power FETs under different input and output voltages. Two high-speed HV body-diode-based zero-voltage detectors are also proposed to realize high-frequency soft switching. Implemented in a 0.5μm 120V CMOS process, the proposed LED driver can support up to 25 series-connected high-brightness LEDs. The LED driver can operate up to 1.6MHz and achieve a peak power efficiency of 94.4% in the soft-switching mode. Compared to the prior arts, the proposed LED driver is the first to demonstrate auto-configurable hard-and soft-switching capability by the ARTC to achieve high power efficiency and current accuracy over both widest ranges of the input voltage and the number of output LEDs.