A new analog dimming circuit used in LED driver

A new analog dimming circuit used in LED power supply was presented. An adjustable duty cycle oscillation signal controlled by external input could change the reference voltage which decided the duty cycle of PWM, then adjusted the output current of LED power supply linearly. Besides, a DAC (Digital Analog Converter) had been used to eliminate the reference voltage jitter which made the dimming more precise. Simulation using Hspice based on TSMC_ 0.5µm BCD process, showed that the linear dimming circuit could control the current of load accurately, and achieved linear dimming LED lights.