Patent attributes
Provided is a deep dimming control method and a driver control circuit for controlling brightness to a plurality of LEDs, that includes a controller which generates a first pulse width modulation signal, and a second pulse width modulation signal is used to switch between closed loop control and open loop control of the light intensity of the LEDs, and at least one comparator configured to receive the first PWM signal or the second PWM signal from the controller. The comparator compares the first PWM signal to a measured output current signal and regulates the output current to the LEDS in the closed loop control until a predetermined output dimming level is reached. Upon reaching the predetermined output dimming level, the controller generates the second PWM signal to another comparator, and the output current is maintained at a preset value determined by calibration during the closed loop control.
