A driver circuit includes a first voltage converter, a light source driver, a second voltage converter and a control circuit. The first voltage converter converts a first voltage to a second voltage. The light source driver is coupled to the first voltage converter, converts the second voltage to a third voltage and outputs the third voltage to a light source for providing light. The second voltage converter is coupled to the first voltage converter, converts the second voltage to a fourth voltage and outputs the fourth voltage. The control circuit is coupled to the second voltage converter to receive the fourth voltage and outputs a first control signal to control the light source driver for controlling the light source. The first voltage is lower than the second voltage, the second voltage is higher than the third voltage, and the second voltage is higher than the fourth voltage.