I. Overview

In automotive electronic systems, “load dump”—a phenomenon occurring at 24V power ports (commonly found in commercial vehicles, trucks, etc.)—is a critical electrical transient event that can cause severe damage to electronic equipment.

  1. What is “Load Dump”?

“Load dump” refers to a scenario where the vehicle’s alternator is charging the battery, and the battery is suddenly disconnected from the system (e.g., due to a loose connection or a broken link). Because of its inertia, the alternator continues to output a high current; however, with the load suddenly removed, the voltage spikes instantaneously. This creates a high-amplitude, long-duration overvoltage pulse—a phenomenon known as “load dump.”

  1. Potential Threats
  • Device Breakdown: Exceeding the voltage tolerance limits of components such as ICs or MOSFETs.
  • PCB Damage: High currents causing circuit traces to melt or burn out.
  • System Resets or Lockups: Microcontroller Units (MCUs) resetting due to power supply anomalies.
  1. According to international standards ISO 16750-2 or ISO 7637-2, the typical parameters for a load dump pulse in a 24V system are as follows:
  • Peak Voltage (Vp): 70V – 100V
  • Duration (Td): Several hundred milliseconds (typically 400ms)
  • Source Impedance: 0.5 – 2 Ω

II. Application Block Diagram

III. Test Standard

P5a: 101V, 4Ω, 400ms

IV. Recommended Components and Description

For TVS protection, the SM8S36A series of automotive-grade TVS diodes—which are AEC-Q101 qualified—is recommended. These devices feature an extremely fast response time (sub-nanosecond) and high surge-absorption capability. They are designed to protect automotive electronic equipment from ESD, EFT, and voltage transients caused by the switching of inductive loads, making them well-suited for harsh automotive load-dump environments. The product datasheet is provided below. For further details regarding product specifications and application information, please visit: https://en.semiware.com/automotive-tvs/sm8s36a/

SM8S36A-Automotive-TVS-Diode-Datasheet下载

V. Application Recommendations

All ECUs and electronic control modules (such as instrument clusters, cameras, controllers, etc.) connected to a 24V main power line should be designed with load-dump protection circuitry.
Perform load-dump testing in accordance with the ISO 7637-2 standard to ensure the system can withstand such pulses.
For critical components, it is recommended to select automotive-grade chips or DC/DC modules that are specifically rated for load-dump tolerance.

Learn More

For more detailed information on load-dump protection solutions for 24V power interfaces in automotive electronics, please contact our engineering team or visit our dedicated reference design page: https://en.semiware.com/reference-designs/dc24v-p5a/. During your automotive electronics design process, you may also provide additional specifications (such as operating voltage, interface type, etc.); we can then assist by developing tailored solutions, supplying AEC-Q101-certified components, and conducting testing and verification in compliance with automotive industry regulations.