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overcurrent/short circuit detection

Paolo Culatti
Prodigy 40 points
Other Parts Discussed in Thread: INA203, INA200, INA206, LMP8601, LMP8481, LMP8480, INA240

Hi,
Referring to the attached schematic, I'm searching for a solution able to measure (no necessary in a accurate way) the current flowing to (from) the load in order to protect the two mosfet (drived by a gate driver IC).
Here follows the application details:
- battery voltage: from 0V to 60V
- The current could flows from the battery to the load (discharge current) but also from the load to the battery (charge current).
- Current value in normal working mode: 40A in both directions
- Shunt value: to be defined but smaller than 0.5mOHM
-
Here follows the current measure circuit requirements:
- Shall be capable to quickly switch off the gate driver when the current (in both directions) is higher then 100A (+/- 15A)
- Shall work in the worst case of short circuit: this means that SNS_a = 60V and SNS_b=GND (and viceversa)
- The total amount of time since the current become higher than 100A to the switch off signal output : 10us (max)
- The solution could consist of one or more IC (in the case of two or more IC please, if it is possible, send me the schematics)
- Cost optimized solution

Thanks a lot for the support
BR
Paolo

current_measure.pdf

  • 0
    TI__Mastermind 26660 points

    Hello Paolo,

    What are the current ratings of M1 and M2? I ask because I am not sure that if the load is shorted to ground that these transistors (or even the battery) will be able to drive the resulting current (60V/Rshunt = kilo-amps). If this would be the case then Rshunt would need an extremely high power rating. If this requirement (60V differential between amplifier inputs) can be reduced, then most of our current sensors with integrated comparators could be used (INA200, INA203, INA206 - these all have -18V to +18V absolute maximum differential input ratings).

    An example of using our comparator integrated sensors would look like this from our INA200 datasheet:

    If the 60V differential input is an unavoidable possibility, the following current sense amplifiers are rated to this: LMP8601, LMP8480, LMP8481, INA240. Each one coming with differing gain options to suit your system. You would most likely want the amplifier you choose to drive a comparator that will then control turning off and on your Gate Driver IC.

    Sincerely,

    Peter Iliya

    Current Sensing Applications