High reliability converter for LED torch

This paper proposed a novel eight-output LED driver which contains a two-output isolated dc-dc converter and two passive current balance circuits connected with outputs of the converter respectively. By controlling switches, the value of output voltage and the number of output channel are determined; therefore the illumination is adjustable, which makes the topology suitable for applications such as flashlight, camping light and emergency light. Furthermore, adjusting any one LED current can control currents through the other 3 channels due to passive current balancing. High efficiency is obtained because of ZVS turned on of switches. Low cost and small size are achieved because comparing with conventional 2-output isolated DC-DC converter, this topology use one less active switch and only two magnetic components. Equations of different operation condition and simulation are employed to analysis the characteristics of this proposed LED driver.