DC-DC Converter with Self-Regulated Output Voltage Control Scheme for Multiple-String Dimmable LED Driver Control

This paper presents a dc-dc converter with self-regulated output voltage (SROV)and phase shift PWM (PSPWM)control methods for multiple LED strings. The LED driver is composed of a boost converter and dimmable current balancing regulators (CBRs). Compared with traditional linear current regulator, the CBR is adopted to reduce power consumption. To keep a designed constant voltage on the CBRs, the output voltage of the boost converter is dynamically adjusted with the SROV control method. It results in high efficiency and current balance of the CBRs and prevents output voltage oscillation. The PSPWM control is employed to mitigate the output current variation supplied by the boot converter, leading to smaller output transient ripple when the PWM dimming signals are changed. The CBRs and control circuits were fabricated with a 0.35-μm standard CMOS technology. The experimental results demonstrate the theoretical analysis of the proposed LED driver.