An LED Driver Based on MCU for LCD Backlight

Abstract:

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.

• Periodical: Advanced Materials Research (Volumes 765-767)
• Pages: 2464-2468
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.765-767.2464
• Online since: September 2013
• Authors: Guang Hua Chen, Gui Zhi Sheng, Feng Jiao Wang, Wen Zhou, Bin Jie Xiao
• Keywords: DC/DC, Joint Frequency-Pulse Width Modulation, LED Driver, MOSFET Driver

References

[1] Cho S H, Lee S H, Hong S S, et al. High-Accuracy and Cost-Effective Current-Balanced Multichannel LED Backlight Driver using Single-Transformer [C]. 8th International Conference on Power Electronics - ECCE Asia, May 30-June 3, 2011, 520-527.

DOI: 10.1109/icpe.2011.5944596

[2] Hsieh C Y, Chen K H. Boost DC-DC Converter with Fast Reference Tracking (FRT) and Charge-Recycling (CR) Techniques for High-Efficiency and Low-Cost LED Driver [J]. IEEE Journal of Solid-State Circuits, 2009, 44(9): 2568-2579.

DOI: 10.1109/jssc.2009.2024051

[3] Lo Y K, Wu K H, Pai K J, et al. Design and Implementation of RGB LED Drivers for LCD Backlight Modules [J]. IEEE Transactions on industrial electronics, 2009, 56(12): 4862- 4871.

DOI: 10.1109/tie.2009.2026771

[4] Liou W R, Lin C Y, Chen T H, et al. Multi-channel Constant Current LED Driver with Temperature and Voltage Compensation [C]. 2010 International Conference on Communications, Circuits and Systems (ICCCAS), 28-30 July 2010, 527-531.

DOI: 10.1109/icccas.2010.5581937

[5] Hsieh Y T, Liu B D, Wu J F, et al. A High Current Accuracy Boost White LED Driver Based on Offset Calibration Technique [J]. IEEE Transactions on Circuits and Systems—II: Express Briefs, 2011, 58(4): 244-248.

DOI: 10.1109/tcsii.2011.2124590

[6] Wu C, Hui S Y R. A Dimmable Light-Emitting Diode (LED) Driver With Mag-Amp Postregulators for Multistring Applications [J]. IEEE Transations on Power Electronics, 2011, 26(6): 1714-1722.

DOI: 10.1109/tpel.2010.2082565

[7] Wang K F. Design and research of High-power LED driver power supply based on Optimized PID algorithm [C]. 20l0 International Conference on Computer, Mechatronics, Control and Electronic Engineering (CMCE), 2010, V3, 372-375.

DOI: 10.1109/cmce.2010.5610291

[8] Zhang J M, Xu L H, Qian Z M. A Precise Passive Current Balancing Method for Multioutput LED Drivers [J]. IEEE Transations on Power Electronics, 2011, 26(8): 2149-2159.

DOI: 10.1109/tpel.2010.2104332

[9] MAX16809/MAX16810 Integrated 16-Channel LED Drivers with Switch-Mode Boost and SEPIC Controller. http: /www. maxim-ic. com.

[10] PIC16F193X/LF193X Data Sheet. http: /www. microchip. com.