An exemplary power supply circuit for providing a driving voltage to a load includes a pulse width modulation (PWM) control circuit, a transformer, a voltage output terminal, and a temperature compensation circuit. The PWM control circuit is configured for outputting a pulse signal. The transformer is configured for converting a first direct current (DC) voltage to a second DC voltage according to the pulse signal. The voltage output terminal is configured for outputting the driving voltage based on the second DC voltage. The temperature compensation circuit includes a temperature sensor for detecting an operation temperature of the load and correspondingly generating a detecting signal, and a feedback signal transmitter for outputting a feedback signal based on the detecting signal. The PWM control circuit adjusts a duty ratio of the pulse signal according to the feedback signal outputted by the temperature compensation circuit.