A Design Of Low Lose Switch Mode Power Supply For LED

Switching power supply with small size, light weight and high efficiency, which has beenwidely used in various fields. Switching power supply power loss mainly by switching powertube losses, switching transformer losses, losses and other auxiliary rectifier circuit losscomponents. Since switching power losses in the loss of the entire supply pipe in the largestshare, the design focuses on the use of soft-switching circuits reduce the loss of the switch soas to enhance the overall efficiency of the switching power supply. This soft-switchtechnology will be applied to the LED(Light Emitting Diode) driver to improve the overallefficiency of the LED power supply.Use of capacitance and inductance of the resonance technology, through the leakageinductance and shunt capacitance of the transformer switch for the upcoming opening of thepower switch is turned to provide zero voltage conditions and to achieve a soft-switching state.This avoids the current and voltage of the switch overlap, reducing the loss of the powerswitch, and improve the efficiency of the LED power supply. About half based on simulationresults, in the60kHz switching frequency, switching power loss soft switching mode onlywhen their hardware switching mode.Using MCU(micro conctroller unit) as a soft switching power supply control chip, themicrocontroller AD input port to the input port of current and voltage feedback signal by twoNMOS transistors and circuit switching half-bridge converter transformers. Microcontrolleroutput is only5V, and NMOS transistors connected to the high side bootstrap driver needed.Achieved using a dedicated chip level conversion and bootstrap driver. By two switches shuntcapacitance and leakage inductance of the transformer utilization charge and discharge thecapacitor to achieve the two switches are in the Soft Switch mode.To simplify the calculation process, the use of computer simulation to optimize circuitdesign. The implementation of a number of circuit testing. Test results show that the powerLED driver with constant current characteristics meet the requirements, the power efficiencyof91%.