In modern electric vehicle (EV) and hybrid systems, battery packs consist of multiple battery modules, each composed of multiple independent battery cells. This design requires a layer of circuit protection. At the module level, preventing overcurrent and overload between the battery modules and cables is crucial.
Furthermore, electronic equipment should be able to suppress voltage transients, while communication buses like the CAN bus should be protected against electrostatic discharge (ESD) and voltage fluctuations.
To ensure stability and reliability, two key risks must be addressed:
⚡ Load sags and high-energy transients on the 12V battery lines
⚡ Electrostatic discharge (ESD) and surge events on the LIN communication bus
1️⃣ Why Are 12V BMS Systems at Serious Risk of Load Dumps?
In automotive environments, so-called transient events occur when the alternator suddenly disconnects the battery while charging, generating surge voltages exceeding 80V–100V. This can lead to:
- MCU damage
- MOSFET breakdown
- Power IC failure
- Reduced system lifespan
High-power TVS diodes can quickly clamp these transient voltages within safe limits.
🔋 Solution
➡️ SM8S24A - 6600W,DO-218AB,Automotive TVS Diode
https://en.semiware.com/automotive-tvs-diodes/sm8s24a
📌 Functions
Installed at the 12V power input of the Battery Management System (BMS) control board, it is used to suppress:
- Load dump
- Alternator transient current
- Battery disconnect surge current
- Cold start spike current
📌 SM8S24 Key Electrical Parameters
| Parameter | Value | Engineering Meaning |
| VRWM (Max) | 24V | Safe operating voltage for 12V system |
| VBR (Min) | 26.7V | Breakdown starts above normal battery range |
| VC @ Ipp | 38.9V | Clamps surge below 40V level |
| Ipp (Max) | 170A | High peak surge handling capability |
| Ppp (Min) | 6600W | Withstands severe load dump energy |
| Package | DO-218AB | High thermal & mechanical robustness |
| AEC-Q101 | Yes | Automotive reliability standard |
📌 Why Is The SM8S24A Suitable For 12V Automotive Networks?
1.VRWM = 24V
- The normal voltage of a 12V vehicle system can rise to approximately 16V.
- A regulated voltage of 24V provides sufficient margin to prevent false triggering.
2.6600W Peak Pulse Power
6600W of power provides a large safety margin for ISO 7637 events.
3.Clamping voltage of 38.9V
Protects downstream devices such as:MCU, PMIC, LDO, CAN/LIN transceivers.
2️⃣ LIN Bus Protection – Why Low Capacitance Matters
LIN bus is widely used in battery management system modules for communication with other vehicle subsystems.
Although the LIN bus operates at relatively low speeds, failure to prevent electrostatic discharge (ESD) can lead to:
- Signal distortion
- Unstable communication
- Increased electromagnetic compatibility (EMC) test failure rate
Therefore, protection devices must possess:
- Sufficient ESD protection
- Low leakage current
- Controllable capacitance
- Automotive-grade certification
🔋 Solution
➡️ PESD1CAN - +15/-24V,13pF,AEC-Q101, SOD-323 ESD Diode
https://en.semiware.com/automotive-esd-diodes/pesd1lin
📌 Functions
PESD1LIN provides dedicated ESD and transient protection for LIN communication interfaces in automotive systems without affecting bus signal performance.
📌 PESD1LIN Key Electrical Parameters
| Parameter | Value | Engineering Meaning |
| VRWM | 15V / 24V | Compatible with automotive CAN voltage levels |
| VBR | 17.1V / 25.4V | Proper breakdown threshold |
| VC @ Ipp | 44V / 70V | Controlled surge clamping |
| Ipp | 5A / 3A | Handles transient current spikes |
| ESD Contact | ±8kV | IEC 61000-4-2 compliance |
| Capacitance | 13pF | Low enough for CAN signal integrity |
| Leakage | 0.05µA | Ultra-low standby power loss |
| Package | SOD-323 | Compact PCB footprint |
| AEC-Q101 | Yes | Automotive qualified |
📌 Why is PESD1LIN?
- Designed specifically for LIN bus applications
- Balanced voltage ratings suitable for automotive signal transmission
- Low leakage current to prevent standby power consumption
- Compact SOD-323 package for space-constrained BMS boards
🗺️ Conclusion
In automotive battery management system (BMS) design, a 6600W rated 12V line TVS diode, paired with a dedicated line ESD diode, can significantly improve:
- load descent immunity,
- surge immunity,
- stable communication performance, and reliability.
If you are designing a 12V BMS module or upgrading your protection strategy, selecting highly reliable automotive-grade components is crucial.
More circuit protection solutions,please visit: https://en.semiware.com/application/
🔹 About Semiware
Semiware is a professional manufacturer of circuit protection and discrete semiconductor devices, headquartered in Shanghai, China.
Founded by experienced engineers in the circuit protection industry, we focus on developing high-reliability TVS diodes, ESD protection devices, GDTs, Triacs, and other discrete components for global OEM and EMS customers.
Our products are widely used in:
- Network & Telecom Equipment
- Automotive Electronics
- Industrial Control Systems
- Security Devices
- New Energy Applications
- Consumer Electronics
We not only supply components, but also provide professional circuit protection design support and EMC technical assistance to help customers improve product reliability.
Stable quality, competitive pricing, and reliable delivery make us a trusted partner for long-term cooperation.
📩 Feel free to contact us for samples or technical discussion. 👉 bella.liu@semiware.com
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