A new protection IC helps safeguard multi-cell lithium batteries against overcharging while reducing power consumption and supporting compact battery-powered electronics designs.
Nisshinbo Micro Devices has launched the NB7400, a secondary protection IC designed for two to four lithium-ion or lithium-polymer cells connected in series. The device provides an independent safety layer for battery packs, helping prevent hazardous overcharge conditions when primary protection circuitry fails.
The NB7400 uses high-voltage-tolerant processing and high-accuracy voltage detection to monitor individual cells. If an abnormal overcharge condition is detected, the IC can trigger an external fuse mechanism to permanently interrupt the charging path. This additional protection is intended to reduce risks associated with severe battery faults.
The IC supports an input voltage of up to 32 V and provides programmable overcharge detection between 4.20 V and 4.85 V. Detection accuracy is specified at ±20 mV, while selectable delay periods help prevent unwanted protection activation caused by electrical noise.
Power consumption has also been kept low. The NB7400 typically draws 2.5 µA during normal operation and can reduce current to as little as 0.2 µA in shutdown conditions when cell voltage falls below the configured threshold.
The device integrates a voltage regulator that can provide 1.5 V to 3.3 V output with ±2% accuracy. This can supply external components such as real-time clocks without requiring a separate regulator, helping simplify battery-pack designs.
Available in a compact DFN(PL)2020-8-GH package, the NB7400 is aimed at applications including power tools, power banks, drones and other lithium-ion battery-powered equipment. Its support for multiple series-cell configurations gives designers flexibility across different pack architectures.
The combination of independent secondary protection, low operating current and integrated regulation could help improve safety while reducing component count in compact battery-powered electronics.
