Overvoltage Protection Circuit

The NCP346 overvoltage protection circuit (OVP) protects sensitive electronic circuitry from overvoltage transients and power supply faults when used in conjunction with an external P-channel FET. The device is designed to sense an overvoltage condition and quickly disconnect the input voltage supply from the load before any damage can occur. The OVP consists of a precise voltage reference, a comparator with hysteresis, control logic, and a MOSFET gate driver.

The OVP is designed on a robust BiCMOS process and is intended to withstand voltage transients up to 30 V. The device is optimized for applications that have an external AC/DC adapter or car accessory charger to power the product and/or recharge the internal batteries.

The nominal overvoltage threshold options are 4.45 or 5.5 V and can be adjusted upward with a resistor divider between the VCC, IN, and GND pins. It is suitable for single cell Li-Ion applications as well as 3/4 cell NiCD/NiMH applications.