Abstract: Charge Pump (CP) is widely used in driving power NMOS in power switch. Ensuring that the voltage generated by the CP remains below the safe gate voltage of the power NMOS requires the overvoltage detection of CP's pumped voltage. In this paper, a Low Voltage (LV) negative feedback loop and a high voltage (HV) PMOS current mirror is employed to precisely apply the CP's input voltage (V_IN) and output voltage (V_CP) across a sensing resistor, enabling precise sampling of the difference between V_CP and V_IN. The voltage difference, reduced by a fixed factor, is then compared with the reference voltage to obtain the output overvoltage flag. The overvoltage detection circuit features a wide input range, high accuracy, and simplicity without the need for a HV comparator. It is fabricated using SMIC 0.18 μm 40 V BCD process, occupying an area of 0.086 mm². Test results indicate that the circuit is capable of accurately detecting voltage differences exceeding 5 V between V_CP and V_IN, with V_IN ranging from 5 to 30 V. Furthermore, the circuit exhibits a maximum current consumption of less than 7 µA.