A driving circuit for illuminating a light emitting unit is provided. The driving circuit includes a data memory circuit, a current source, a PWM control circuit, a buffer circuit, and a second switch. The data memory circuit stores a data signal according to a scan signal. The current source generates a driving current. The PWM control circuit generates a PWM signal according to an enable signal and the data signal stored in the data memory circuit. The buffer circuit receives the PWM signal to generate a PWM signal. The second switch passes the current source through the light emitting unit according to the PWM signal so that the driving current flows through the light emitting unit.