Abstract: A novel circuit is designed to solve the overvoltage protection of power management systems. The presented circuit directly compares the current caused by external voltage with the reference current. Hspice simulation results show that the consumption currents of the designed circuit in normal state and over-voltage state are 104 μA and 26 μA, only 41.9% and 15.2% of the conditional structure, respectively. The number of the devices used in the structure is 50% of the conditional structure. The designed structure has been implemented in 0.4 μm BCD process.