MOSFETs in Electric Vehicle Battery Management Systems: Core Functionality & Selection Insights

This article describes the application scenarios and parameter selection of MOSFETs in BMS systems, covering pre-charge control, battery protection, and high-frequency switching requirements. It is suitable for EV OEMs and module integrators.

I. Background: EV Growth Drives Power Device Innovation

With the rapid growth of the global electric vehicle (EV) market, particularly in China, Europe, and North America, Battery Management Systems (BMS) have become critical subsystems. This drives higher performance and reliability standards for power semiconductor devices.

MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) are increasingly used in BMS due to their high switching speeds, low RDS(on), and excellent thermal performance—ideal for current control, pre-charging, and battery protection.

II. Key Applications of MOSFETs in BMS

1. Charge and Discharge Path Control

MOSFETs are commonly used as main circuit switches to manage charging and discharging paths. N-channel devices, with their strong conduction capability, are ideal for high-side or low-side configurations.

Recommended models such as Infineon IRF1405PBF and ON Semi NVMFS5C442NL offer low RDS(on) and automotive-grade reliability.

2. Overvoltage, Overcurrent, and Short Circuit Protection

Paired with detection ICs, MOSFETs form protective circuits that instantly shut down during abnormal conditions to prevent battery damage.

Devices like TI CSD18510KCS and Vishay Si7336ADP provide strong breakdown voltage and effective thermal dissipation.

3. Pre-Charge Circuit Control

Pre-charge circuits control current into large capacitors to avoid surge current during startup. MOSFETs offer smooth and safe switching paths.

ST’s STP75NF75 and ROHM’s R6020ENX are widely adopted for their voltage tolerance and switching performance.

III. Key Parameters and Selection Guidelines

Parameter	Definition	Recommendation
VDSS	Drain-source withstand voltage	Higher than 1.3 times the maximum system voltage
ID	Maximum drain current	Meet the actual peak operating current
RDS(on)	On-resistance	The lower the better, reducing power consumption and heat generation
Qg	Gate charge	The smaller the size, the faster the switching speed and the simpler the control.
Package	TO-220, DFN, SOP, etc.	Combine space and heat dissipation layout selection

IV. Case Study: MOSFET Deployment in 400V EV BMS Platform

In a European mid-size SUV project, the BMS required a MOSFET capable of handling continuous 20A current while ensuring adequate voltage tolerance, thermal stability, and EMC compliance.

The chosen solution—Nexperia’s PSMN2R8-80BS—offered a low 5mΩ RDS(on) and D2PAK package for optimized heat dissipation and assembly.

V. Our One-Stop MOSFET Supply & Service

We stock and distribute MOSFETs from the following top-tier brands:

● Infineon

● ON Semiconductor

● Texas Instruments (TI)

● STMicroelectronics

● ROHM

● Nexperia

We offer:

● Automotive-grade AEC-Q101 parts

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