Surge and transient pulse testing reproduces the voltage spikes and transient events in a vehicle electrical system. The product must keep functioning normally, or enter a safe state, under these conditions. Automotive work follows CISPR 25 and the ISO 7637 series.
Typical disturbance scenarios
Load dump: the high reverse electromotive force generated at the instant an inductive load is disconnected.
Jump starting: the transient produced when battery terminals make poor contact with the vehicle body.
Generator regulation fault: momentary fluctuation of the output voltage.
Ignition transients: disturbance generated by ignition coil operation.
Test items
Pulse voltage test: reproduces the positive and negative voltage spikes produced by load dump and similar events.
Pulse burst test: reproduces the high-frequency pulse train generated when an inductive load is disconnected (rise time and repetition rate are the key parameters).
Voltage change and recovery: reproduces the voltage dip and recovery when the engine starts.
Protection design essentials
Place a TVS diode across the input. The clamp voltage must be below the absolute maximum rating of the downstream circuit, with design margin left over.
Add sufficient filter capacitance at the input to suppress the transient current caused by voltage spikes.
ISO 7637-2 pulses need devices with wide bandwidth and high surge capability; pulse bursts demand even more bandwidth.
Place the TVS close to the interface on the PCB, with the return path straight to the ground plane rather than through digital areas.
On the software side, monitor the supply voltage and handle anomalies, entering a safe state on undervoltage.
Frequently asked questions
Can surge testing damage the sample?
It can. Surge energy is substantial, and if the protection design is inadequate the damage is irreversible. That is part of design validation — it surfaces protection weaknesses early. It is best done during development rather than after mass production starts.
How should a TVS diode be selected?
Three key parameters: reverse standoff voltage (must not conduct at the operating voltage), clamp voltage (the voltage actually limited during a surge, which must be below the downstream withstand rating), and peak pulse power (must cover the actual surge waveform). Also check junction capacitance, which matters more when selecting for high-speed signal lines.
Service notes
Our laboratory holds both CMA and CNAS accreditation, covers about 10,000 m2 and runs more than 500 sets of equipment. All testing is carried out in our own laboratories — nothing is subcontracted. Plant visits and on-site witnessed testing are welcome.
Scheduling follows the actual project pipeline. You can state your preferred lead time when you submit samples; we will confirm a feasible plan against current capacity and keep you updated at each milestone. Once the report is issued we send the electronic copy; corrective-action advice can be arranged separately.
