A high-side transistor driver including a driver circuit for generating a driving signal to drive a high-side transistor is provided. A floating supply terminal provides a supply voltage to the driver circuit. A floating ground terminal is connected to a source of the high-side transistor. A bootstrap diode is coupled between the floating supply terminal and a voltage source. A capacitor is connected to the bootstrap diode and is coupled between the floating supply terminal and the floating ground terminal. A high-voltage transistor is used for switching off the driving signal and the high-side transistor in response to an input signal. A speed-up capacitor is coupled to the driver circuit for speeding up the driving signal. Furthermore, the positive feedback circuits in the driver circuit further accelerate the driving signal and save power for the driver circuit.