A hostwap controller as the shown here is used to to precharge and control a high side load:
In a hotswap control Q1 will spend some time in the saturation region during start up and turn off to control the inrush and will then move to the triode region to basically work as a switch once in steady state.
For the saturation region it's important to ensure the FET remains within its SOA to avoid it failing.
Here is an example SOA:
If a FET is nearing its SOA, one option would be to find a FET which is within spec. However, the other option I hear is to reduce the inrush by slowing down turn on (change value of C3 basically).
Here TI mentions that total energy dissipated through the FET is the same so you might as well reduce the peak current as the VDS drops. However, increasing C3 means you would spend longer in Saturation and SOA limits depend on that too. Is there a sweet spot for using C3 then? How can I set C3 and ensure it stays within SOA from design calculations? I could get an EVM and test with load too.
