A Current-Accuracy-Enhanced Wide-Input-Range DC–DC LED Driver With Feedforward Synchronous Current Control

摘要

A wide-input-range (5-115 V) current-accuracyenhanced dc-dc LED driver is presented in this paper. A feedforward synchronous current control (FSCC) scheme is developed to improve the LED current accuracy over wide ranges of input and output voltages. In the FSCC, a reconfigurable valley current sensor is proposed to provide accurate positive and negative valley inductor current information for the controller corresponding to hardand soft-switching modes, respectively. A dynamic peak reference generator is developed to automatically adjust the peak current reference value dependent on input and output voltages for reducing the deviations of the average LED current under different input voltages and numbers of output LED, thereby improving the current accuracy. Implemented in a 0.5-μm 120-V CMOS process, the experimental results show that the proposed LED driver IC achieves a current accuracy within ±6.0% of the average LED current of 350 mA over an input voltage range from 5 to 115 V and numbers of seriesconnected LEDs from 1 to 25 by using only a small inductor of 10 μH. Compared with the state-of-the-art synchronous current control scheme, the variations of the LED current can be reduced by 2.3 and 4.2 times in the hardand soft-switching modes, respectively, with the proposed LED driver using the FSCC.