VN7003: Short circuit protection failure

[Minloud]

Dear ST Technical Support,

I would like to inquire about the short-circuit protection behavior of the VN7003ALH high-side switch.

Application: Board with 6× VN7003ALH outputs.

Configuration: 24V supply from 200Ah lead-acid battery. Output wiring: 1.5m of 12 AWG.

Issue: With output ON, a hard short circuit was applied via 600A mechanical contactor. The VN7003ALH did not survive — the package cracked (photo attached).

Question: Is this behavior expected? We assumed the integrated short-circuit protection would handle such transients. Are there specific source impedance or di/dt limitations we should be aware of that are not covered in the datasheet?

Best regards,
Artem

 

[Peter BENSCH]

Welcome  @Minloud, to the community!

With a 24 V/200Ah lead‑acid battery, 12 AWG wiring and a 600A mechanical contactor, the source can deliver extremely high peak current with very low impedance and very fast di/dt. In this condition, the current can far exceed the short‑circuit withstand capability of the VN7003ALH before the internal protection has time to react, so device destruction (cracked package) is unfortunately expected.

The integrated protection is designed for short circuits within the limits defined in the datasheet (including supply, wiring impedance and transient energy), not for effectively unlimited fault current from a large battery switched by a low‑impedance contactor.

To use the VN7003ALH safely in this environment, additional external measures are required, such as:

• series impedance / wiring or dedicated inrush/limiting elements
• appropriately rated fusing or circuit breakers placed close to the battery
• layout/wiring that ensures a minimum loop impedance

Are you able to share the battery specs and any upstream protection, maybe we can then help to estimate the required external limitation?

Regards
/Peter

[Minloud]

Hello @Peter BENSCH 

The intention was to use this IC as load switch/efuse.

The device has an mcu to control each of VN7003 managed outputs. I can sense the current and perform short circuit protection by software as workaround for current production batch. Unfortunetly the datasheet does not provide any information about the FET SOA so I can't estimate timings for reliable software protection and current spike filters.

I'm afraid I can't rely on VN7003 passive protection and should migrate to other products.

Best regards,
Artem