Implementation of a Dimmable LED Driver with Extendable Parallel Structure and Capacitive Current Sharing

Hwu Hwu,Tai Tai,Tu Tu

doi:10.3390/app9235177

Abstract

A dimmable LED driver along with an extendable series structure and interleaved capacitive current sharing is presented herein, the LED connection of which is changed from the traditional series structure to the proposed parallel structure. The number of LED strings can be extended. As the number of LED strings is increased, the output voltage of this LED driver and the voltage stress on the main switch are ideally not influenced. Moreover, only one current sensor is needed to achieve current control and dimming. In this paper, the basic operating principle of the proposed LED driver is described and analyzed. Finally, the effectiveness of this LED driver is demonstrated by experiment based on the field-programmable gate array (FPGA).

Highlights

IntroductionLEDs are getting more attractive in the world due to their small size, light weight, and long life [1,2]
As generally recognized, LEDs are getting more attractive in the world due to their small size, light weight, and long life [1,2]
LED driver is described and analyzed. The effectiveness of this LED driver is demonstrated by experiment based on the field-programmable gate array (FPGA)

Summary

Introduction

LEDs are getting more attractive in the world due to their small size, light weight, and long life [1,2]. The higher the current in the LED, the higher is the forward-biased voltage across the LED [4]. The higher the temperature in the LED, the lower is the forward-biased voltage across the LED. The arrangement of LEDs is first in series and in parallel, so as to avoid a high voltage across the output of the LED driver. The current balance among LED strings is very important so as to avoid uneven currents in the LED strings. These uneven currents will affect the LED luminance and cause the temperature in the LED to be increased and the life of the LED to be reduced. Many literatures have presented current-sharing methods for LED strings [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21] so as to make currents distributed among LED strings as identically as possible

Methods

Results

Discussion

Conclusion