The Design And Realization Of Driver For LED Backlight Of Large LCD TV

The LED backlight driver circuit system is the key to the reliability, service life andenvironmental protection and energy saving of large-size LCD TV.Reliable and efficient for the purpose, this paper analyzed the related topologicalcircuit and the circuit system that has been used to the LED driver of LCD TV,applied the advantage of the LLC topology to the LED driver innovatively, integrateddesign with a stable power supply circuit, and then realized the reliable and efficientdriver system of LED backlight. At the last part finish the circuit system withboard-level implementation and rigorous test validation. And acomplished theinnovations in the following aspects:For the system architecture, using LLC topology circuit which have high workingefficiency and stable output, this design creatively use the positive and negativevoltage that is outputted by the inductance to constant-current drive the LEDbacklight directly. This way could change traditional mode that two lights need twodriver systems, also could improve the consistency and accuracy of the two LEDlightstings controlled by constant current. There also have advantages that using lesselectrolysis, solving the bottleneck that electrolysis in high temperature easilyevaporated and then affect the service life. Finally, the system reliability have beengreatly improved and the driver efficiency of LED can be increased to more than90%.For the energy saving, this paper designed the power supply circuit with aconversion circuit for standby, and chose an ultra-low standby power consumptionchip NCP1246, design with frequency-hopping way to reduce the power consumptionin standby condition coupled with the no discharge resistor AC-DC circuit, achievethe ultra-low standby power consumption that lower than the standard “Energy Star”of0.5W. And with the use of high-efficiency PFC circuit for power factorcorrection coupled with the highly efficient and stable voltage output LLC resonantcircuit, the system can achieve an efficient energy saving feature.For driver protection, this paper use an error amplifier to set up a protectionfunction main circuit, easily achieved the reliable OVP, OCP, short circuit protection,open-circuit protection and over power protection functions.Further improved thesystem design of security and reliability of the LED driver circuit based on LLCtopology.The driver circuit system design and implementation in this article have somereference value for future research and application in LED driver circuit, and havesome economic value for LED backlight LCD TV product.