An LED Driver Based on MCU for LCD Backlight

in order to provide LCD backlight with multiple strings of LEDs, an LED driver based on MCU is proposed in the paper. A PWM signal is generated by the Pulse Width Modulation (PWM) module on the MCU chip, which is used to drive a DC-DC boost converter for LED power. The voltage and current of the boost circuit, along with all the channels current of LED, are measured by the Analog Digital Converter (ADC) module on the MCU chip, which are used to adjust the voltage of the boost circuit and supply comprehensive protection for the LED driver. To minimize the step size of the output voltage, the joint frequency-pulse width modulation scheme is proposed to regulate the output voltage of the boost circuit to an ideal value in the range of error, which increases the efficiency of the power. The measurement results show that the LED driver is extremely efficient and steady. Most of the output voltage step size is about 0.1V, the maximum step size is less than 0.3V. The conversion efficiency of the DC-DC converter is up to 94%. Thus the LED driver not only meets the demand of the parameter of LED, but also has high cost performance.

[1]  Ke-Horng Chen,et al.  Boost DC-DC converter with charge-recycling (CR) and fast reference tracking (FRT) techniques for high-efficiency and low-cost LED driver , 2008, ESSCIRC 2008 - 34th European Solid-State Circuits Conference.

[2]  Yu-Kang Lo,et al.  Design and Implementation of RGB LED Drivers for LCD Backlight Modules , 2009, IEEE Transactions on Industrial Electronics.

[3]  Ying-Zong Juang,et al.  A High Current Accuracy Boost White LED Driver Based on Offset Calibration Technique , 2011, IEEE Transactions on Circuits and Systems II: Express Briefs.

[4]  Wu Chen,et al.  A Dimmable Light-Emitting Diode (LED) Driver With Mag-Amp Postregulators for Multistring Applications , 2011, IEEE Transactions on Power Electronics.

[5]  Zhaoming Qian,et al.  A Precise Passive Current Balancing Method for Multioutput LED Drivers , 2011, IEEE Transactions on Power Electronics.

[6]  Sung-Soo Hong,et al.  High-accuracy and cost-effective current-balanced multichannel LED backlight driver using single-transformer , 2011, 8th International Conference on Power Electronics - ECCE Asia.

[7]  Wan-Rone Liou,et al.  Multi-channel constant current LED driver with temperature and voltage compensation , 2010, 2010 International Conference on Communications, Circuits and Systems (ICCCAS).

[8]  Wang Kefei.  Design and research of high-power LED driver power supply based on optimized PID algorithm , 2010, 2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering.

[9]  Ke-Horng Chen,et al.  Boost DC-DC Converter With Fast Reference Tracking (FRT) and Charge-Recycling (CR) Techniques for High-Efficiency and Low-Cost LED Driver , 2009, IEEE Journal of Solid-State Circuits.