With vehicles like Tesla Cybertruck leading the transition to 48V electrical architectures, the automotive industry is rapidly evolving beyond traditional 12V systems.

While 48V brings significant advantages in efficiency and power delivery, it also introduces new challenges—particularly in power integrity and communication reliability.

Among these, ESD and surge protection for power lines and CAN interfaces have become critical design considerations.

I. Why Use a 48V System?

Traditional gasoline vehicles have long used a 12V low-voltage system. However, with the increasing number of electronic devices in automobiles (such as start-stop systems, electric air conditioning, active suspension, electric turbochargers, etc.), the 12V system has gradually become overburdened. Therefore, the industry has shifted to 48V mild hybrid systems.

Advantages of 48V Automotive Systems：

AdvantageDescription
Lightweight WiringHigher system voltage allows lower current for the same power (P = VI), enabling the use of thinner and lighter cables. This reduces overall vehicle weight and improves energy efficiency, which is especially critical for EV range optimization.
Higher EfficiencyReduced current significantly lowers I²R losses (Joule heating), minimizing energy dissipation and improving overall system efficiency, contributing to better fuel economy and reduced emissions.
Support for High-Power Loads 48V systems can efficiently supply high-power components such as electric compressors (~22.5 kW), electric power steering, active suspension, and e-turbochargers. In 12V systems, such loads would require excessively high current, leading to overheating and instability.
Optimized Cost-Safety Balance48V remains below the 60V safety threshold, avoiding the need for complex and costly high-voltage protection measures (e.g., insulation monitoring and leakage protection) required in 400V EV systems. This reduces both system cost and design complexity.

II. Role of CAN Bus in 48V Architecture

The 48V CAN bus is a standard communication network operating in 48V mild hybrid or high-voltage architectures. It connects the 12V and 48V systems, enabling coordinated control between multiple ECUs. In modern automobiles, especially those equipped with 48V mild hybrid systems (such as Mercedes-Benz, Audi, and Cadillac), there are two main power systems:

  • 12V low-voltage system: Powers traditional electronic devices (instruments, lights, ECUs, etc.).
  • 48V high-voltage system: Powers high-power components such as the starter motor, electric turbocharger, and air conditioning compressor.

For these two systems to work together efficiently, they rely on the 48V CAN bus to transmit critical commands, such as the engine ECU sending a start command to the 48V starter generator.

III. Three Core Functions of the 48V CAN Bus

  • Cross-Domain Communication: Connects 12V and 48V systems, transmitting critical information such as start-stop, energy recovery, and fault diagnosis.
  • Coordinated Control: Unifies the scheduling of systems such as the engine, transmission, battery, and air conditioning, improving energy efficiency and driving experience.
  • Functional Support: Provides the communication foundation for functions such as idle start-stop, coasting energy saving, kinetic energy recovery, and intelligent cruise control.

IV. Why ESD Protection is Critical for 48V CAN Systems

1. Higher Voltage Increases ESD Coupling Risk

A higher system voltage amplifies the impact of electrostatic discharge, increasing the likelihood of damage to sensitive communication lines.

2. Increased Noise from High-Power Switching

48V systems integrate components such as ISG motors and electric compressors, which generate high-frequency switching noise that can couple into CAN lines.

3. Safety-Critical Communication Dependency

CAN bus failures may result in:

  • ECU malfunction
  • Start-stop failure
  • Dashboard blackout
  • Safety system misoperation

V. Semiware's Protection Solutions for 48V Power and Signal Interfaces

Semiware provides a comprehensive protection solution for 48V systems using a combination of TVS diodes, Schottky diodes, PTC fuses, and Zener diodes.

Part NumberDescriptionCurrent RatingPackageDatasheet
5.0SMDJ58CATVS Diode, 58V, bidirectional, 5kW53.5 A
DO-214AB		https://en.semiware.com/tvs-diodes/5-0smdj58ca/
SM8S58CATVS Diode, 58V, 6600W @10/1000µs, AEC-Q101 compliant70.5A
DO-214AB		https://en.semiware.com/automotive-tvs-diodes/sm8s58ca/
BZT52C15SZener Diode, 15V, 200mW/SOD-323https://en.semiware.com/zener-diodes/bzt52c15s/
SK60-500PTC Resettable Fuse, 60V, 60 mΩ5ASK60https://en.semiware.com/pptcs/sk60-500/
SS510CQ

Schottky Diode, 100V, 5A, AEC-Q101 compliant5ASMChttps://en.semiware.com/schottky-diodes/ss510cq/

Conclusion

By integrating TVS diodes, Schottky diodes, PTC fuses, and Zener diodes, Semiware’s 48V protection solution ensures both power and communication reliability, safeguarding modern automotive systems against ESD, surges, and overcurrent events, and enabling stable operation of high-power 48V components and safety-critical CAN networks.

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, datasheets, or technical support. 👉 https://en.semiware.com/contact/