Load Dump TVS (DO-218)
Heavy-duty TVS purpose-built for automotive 12 V / 24 V load-dump surge events.
What is it?
A load dump occurs in vehicles when the battery is suddenly disconnected while the alternator is charging it (for example a loose or corroded battery cable). The alternator's stored magnetic energy then dumps into the 12 V or 24 V rail. In the ISO 16750-2 test this is a pulse of up to about 100 V on a 12 V system (about 200 V on 24 V) lasting 40-400 ms. Standard 8/20 μs TVS will fail this; the pulse is far too long. Load-dump TVS in the DO-218 package have a large die and are rated with 10/1000 μs and 10/10000 μs pulse power to absorb the multi-joule load-dump energy.
When do you need it?
- Any automotive 12 V or 24 V power rail input on an ECU, infotainment unit, or accessory.
- Load-dump tests to ISO 16750-2 Test A (unsuppressed) or Test B (suppressed), formerly ISO 7637-2 pulse 5a / 5b.
- ISO 16750-2 protection requirements for automotive electronics.
- Heavy trucks and industrial vehicles with 24 V systems where transients reach 200 V+.
- Power-input modules for off-road / marine / agricultural equipment.
How to pick the right one
- VRWM matched to rail
- Use 24-27 V VRWM for 12 V automotive rails (allows for 16 V jump-start headroom). Use 36-40 V VRWM for 24 V truck rails.
- VC at full IPP
- Check the 10/1000 μs clamping voltage, not just the 8/20 μs spec. Load dump is a long pulse, the device may clamp higher under the longer waveform.
- IPP at 10/1000 μs
- Standard 8/20 μs IPP is misleading for load dump. The 10/1000 μs IPP rating is the one that matters. Magnias DO-218 parts are rated about 95 A to 330 A at 10/1000 μs.
- Power dissipation
- A load dump puts several joules into the TVS. Check the 10/10000 μs power rating too, since it is closer to a real load dump (Magnias: 5200 W for SM8S / SM8Q, 6000 W for SM8T).
- AEC-Q101 qualification
- Mandatory for automotive use. Magnias DO-218 load-dump parts are AEC-Q101 qualified.
What Magnias offers
Magnias offers DO-218 load-dump TVS for 12 V and 24 V automotive rails: SM8S (12-43 V) and SM8Q (12-36 V) at 6600 W, and SM8T (24-36 V) at 8000 W (10/1000 μs), with IPP from about 95 A to 330 A, uni- and bi-directional versions, all AEC-Q101 qualified. The SM8Q and SM8T datasheets state ISO 16750-2 load-dump compliance (SM8Q also ISO 7637-2 pulse 5a / 5b); check each series datasheet for the test conditions. For applications that also see IEC 61000-4-5 surge, pair a standard 8/20 μs TVS with the load-dump TVS: the fast TVS clamps the short surge, the load-dump TVS absorbs the long pulse.