High power density is a key point that power converters endeavor to pursue. However, it is rare that gate driver of power converter can switch under high supply voltage with a fast operation frequency. In this paper, a half-bridge driver with the slew rate enhancement (SRE) technique is proposed and its switching frequency can be increased to 25MHz under a 700V supply voltage. Besides, the proposed high voltage clamping circuit ensures all circuits operating in a safe region without any overvoltage problems in the bootstrap operation. With specifically developed high voltage high speed (HVHS) process, high-side and low-side circuits can be well shielded by the isolation well which is embedded in the level shifter device to minimize chip size.