Nisshinbo Micro Devices NB7400

The NB7400 is a highly integrated secondary protection IC designed for 2 to 4 lithium-ion or lithium-polymer battery cells connected in series. Engineered with a high-voltage tolerant process and precise voltage detection technology, the NB7400 is tailored to meet the stringent safety requirements of modern battery-powered applications. The NB7400 offers an additional layer of security in multi-cell battery applications. While primary protection ICs typically manage standard charge/discharge cycles and basic threshold monitoring, secondary protection ICs are critical in scenarios where the primary circuitry fails or becomes unresponsive. The NB7400 detects abnormal overcharge conditions independently and triggers a fuse-blowing mechanism to interrupt the charging path permanently, effectively preventing hazardous scenarios such as thermal runaway or battery rupture. The NB7400 supports the supply voltage tolerance of up to 32 V, and offers overcharge detection voltages programmable between 4.20 V and 4.85 V with high accuracy (±20 mV at 25°C). It also incorporates an optional overcharge timer reset delay, ensuring resilience against noise-induced false triggers, with delay times configurable to 2, 4, or 6 seconds. Key attributes of the NB7400 include an ultra-low operating current of just 2.5 µA during normal operation, and switches to a minimal shutdown current of 0.2 µA to conserve battery life, activated when any cell voltage falls below a configurable threshold. To support external components like real-time clocks, it integrates a built-in voltage regulator delivering a stable output between 1.5 V and 3.3 V, accurate within ±2%. The NB7400 is available in multiple configurations, with selectable set voltages, delay times, and output voltages tailored to specific design needs.

Key features

• Absolute maximum ratings: 32 V
• Low supply current: Normal operation (Cell voltage: 4.15 V, 4 cells): Typ. 2.5 μA, Shutdown (Standby): Max. 0.2 μA
• Overcharge detection voltage (V_DET1n) and accuracy: 4.20 V to 4.85 V, ± 0.020 V (Ta = 25°C), ± 0.025 V (0°C < Ta < 60°C)
• Overcharge detection delay time with delay time shortening: (1) 2-, 4-, or 6-sec
• VROUT (built-in voltage regulator) pin output voltage (V_VROUT) and accuracy: 1.5 V to 3.3 V, ±2%
• Shutdown detection voltage (V_SHTDn) and accuracy: 2.0 V (2) to 3.0 V, ± 0.05 V
• Package NB7400GH: DFN(PL)2020-8-GH

Applications

• Power tools
• Power banks
• Drones
• Li-Ion battery pack