Digital dimming control system for light-emitting diode (LED) and method thereof

A digital dimming control system for a light-emitting diode (LED) comprises a main power circuit and an LED load, is provided with an external control input module and comprises a control module, a pulse width modulation (PWM) driving module, a digital to analog (D/A) conversion module, a feedback circuit and a comparator, wherein the control module comprises decoding unit, a driving control unit, a time keeping unit and a timing unit. The control module adjusts switching time of PWM driving waveforms by controlling the PWM driving module according to the requirements of the external control input module; on one hand, the driving control unit changes a voltage reference value Vref of the input end of the comparator through the D/A conversion module, and on the other hand, the driving control unit controls connection of PWM signals. The time keeping unit is used for calculating connection time of the PWM during every period, the timing unit is used for determining the switching time of the PWM, the driving control unit guarantees constancy of a switching period of the PWM driving module through the timing unit, and by comparing time Treal obtained by the time keeping unit and storage time Tstatic inside the driving control unit, the driving control unit adjusts the connection time of the PWM and achieves corresponding protection.