Electronics > Power/Renewable Energy/EV's

Thermal Protection of ORING circuit

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Magnethicc:
Hello everyone,
I have a 57A ORING circuit (using LTC4357 and 3xD2PAK MOSFETs in parallel).
We noticed that during an abnormal situation where there may be a short between the gate and the source of one of the MOSFETs that the ORING controller no longer works and the entire current flows through the body diodes of the MOSFETs causing them to overheat in a smoky fashion.

Do you have any ideas on how to protect thermally in case of MOSFETs not working?

SeanB:
Littelfuse LR range polyswitches in parallel, held on top of the MOSFETS should help, as they also will trip when hot, and are rated for 100A breaking current. You would need 6 13A devices in parallel.

https://www.littelfuse.com/media?resourcetype=datasheets&itemid=d79bb3c2-7bcd-4a2d-8e2d-8a68259bd728&filename=littelfuse-ptc-battery-strap-lr4-datasheet

When they get hot trip current decreases, so the hot transistor will result in one tripping, followed by the others in very short order.

f4eru:
partial circuit may be helpful.

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