BMS (Battery Management System) is responsible for monitoring, controlling, and protecting batteries to ensure their efficient operation and safety.

MOSFET plays a role in detecting overcharging, over-discharging, and overcurrent during battery management.

In the charging state, when the battery is overcharged, the charging control terminal switches from a high level to a low level, turning off MOSFET Q1 and cutting off the charging circuit, entering overvoltage protection.

When the battery discharges through the load and the battery voltage drops below the set value, the discharge control terminal switches from a high level to a low level, turning off the discharge control MOSFET Q2 and cutting off the discharge circuit, entering undervoltage protection.

Lithium batteries are often connected in series, and the number of batteries determines the voltage level. Therefore, the selection of MOSFETs is related to the number of batteries.

Usually, when determining the voltage of the battery pack, the voltage of the MOSFET is selected with a 20% margin. In actual applications, lithium batteries require MOSFETs with low internal resistance due to their high temperature requirements.

Considerations in selection:

1. Determine the number of parallel MOSFETs and the appropriate RDS(ON) through thermal design.

2. Choose MOSFETs with smaller RDS(ON) so that the total on-resistance can be further reduced when multiple MOSFETs are connected in parallel.

3. Finally, consider the voltage spikes in the late stage of shutdown. The avalanche energy of the MOSFET should not be too small.

VBsemi has been focusing on MOS products for more than 20 years, with rich product models and diverse packages, suitable for high-performance BMS scenarios such as electric vehicles.