The majority of today’s handheld and battery-powered tools and equipment are reliant on multi-cell lithium-ion battery packs. Li-ion batteries have the advantage of high energy density. However, in a fault condition this can become problematic with the potential for a massive uncontrolled energy discharge, resulting in over-heating of loads and potential circuit fires.
To handle any significant discharge in a controlled manner until the battery is safely isolated and the system switched off requires an extremely robust and thermally efficient MOSFET – the ideal application for Nexperia’s toughest LFPAK-housed devices.
ASFETs for battery isolation are designed specifically for multi-cell battery powered equipment:
- • In a fault situation, the battery isolation MOSFET normally goes into linear mode due to voltages being developed across circuit inductance at high current when the fault causes a deep discharge.
- • Strong SOA MOSFETs continue to operate safely and controllably until switch off and the battery is fully isolated from the load circuit.
- • A low RDS(on) is required for low conduction losses in normal operation, but parameters need to be optimized for safe battery isolation.
- • Robust battery isolation MOSFETs can be used as the primary protection for equipment approval.
- • A low Vt may be required, as battery protection ICs may only have a 2–3 V gate drive.
Download Designing in MOSFETs for safe and reliable gate-drive operation
Download Maximum continuous currents in NEXPERIA LFPAK power MOSFETs