PWM 및 PFM 제어 기반 LED 전광판 전원회로 설계

Abstract

In this paper, We design the optimal power supply for LED Display board. The power supply used in the display board provides the LED module with 5V. The proposed power supply provides the LED module with LED driving voltage by color. The power supply is controlled by digital control program. The initial duty of the control program sets output voltage of buck converter to be 2.6V and 3.8V. The power supply uses control program for stable output voltage. The proposed power supply operate in PWM(Pulse Width Modulation) control at moderate to heavy loads, under light load condition the converter operate in PFM(Pulse Frequency Modulation) control. The power supply can be switched to PWM control mode when the load current is greater than 60mA, and can be switched to PFM control mode when load current is under 60mA. Simulation was used the EVM board and the LED module. We checked by simulation that the PWM and PFM function of power supply work fine and measured the efficiency of the power supply. When the load current is under 60mA, efficiency of power supply is 8% higher than. When the LED module is operated by using the proposed power supply, the power consumption of the proposed power supply is 40% less than before. The proposed power supply provides the LED module with the necessary voltage to reduce power consumption of LED module.