A projector drive circuit includes a first voltage converter, a light source driver, a second voltage converter, and an isolation circuit. The first voltage converter converts a first voltage into a second voltage. The light source driver converts the second voltage into a third voltage. The second voltage converter converts the second voltage into a fourth voltage. The control circuit, coupled to the second voltage converter, receives the fourth voltage and outputs a first control signal. The isolation circuit, coupled to the control circuit and the light source driver, receives the first control signal and generates a second control signal to the light source driver, which controls the light source driver to generate the third voltage and provide the third voltage to a light source according to the second control signal. The isolation circuit electrically isolates the control circuit from the light source driver.