Hi,
At present, I'm looking to develop a current sensor capable of measuring up to 300A of current on a 50V power source, and I'm trying to make my system robust in case of a reverse voltage event (rare, but potentially very costly). I have a circuit designed using the INA240 on a 3.3V supply with the REF pins biased by a voltage divider on the same 3.3V supply. While I've been able to incorporate upstream reverse voltage protection circuits for lower current (20A or less) sensing applications, I don't see this as a viable option for my application due to the very high current and my space constraints. I've also looked for other current sense amplifiers designed to handle -50V, but I haven't really found anything. I'm willing to let the INA240 fail (i.e. fry), provided the power source's reversed 50V doesn't cascade through and create reverse voltages on the output or the 3.3V supply. The 3.3V supply is downstream of the current sensor and does have reverse voltage protection in place, so it will not be supplying any power in a reverse voltage event.
Do I need to be concerned about a sustained -50V common mode voltage creating negative voltages on the VS or OUT pins before the chip fries? If so, what would be the best way to guard against this? I've thought about using TVS diodes to clamp the pins and fuses to break their connections if there's unusually high current (say, 50mA), but I wanted to see if anyone else had any ideals.
Thanks,
Wil