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INA240-Q1: Higher voltage INA240-Q1

Part Number: INA240-Q1
Other Parts Discussed in Thread: INA281, INA240, AMC1300, INA239, ISO7842, INA260, DRV425


Could I please get a bit of product advice? 

I am working on a higher voltage ESC design, about 120V. I would like to do in-line phase current measurements (bidirectional). The INA240-Q1 would be perfect, except for it's 80V limit. I know that you have higher voltage parts like the INA281. However, the voltage is not quite there; especially since a bit of margin would be nice (and required). 

Do you have a new version of the INA240 coming out that supports higher voltage, or can recommend another part or solution? 



  • Jason,

    Unfortunately, the INA281 is the highest common mode part that we make today. We are constantly working on newer devices that will push the boundaries of common mode voltage, but 120V survivability (110V recommended operating range) is the highest common mode voltage today that we offer. 

    Can you share a bit about the application here? You are looking at the INA240-Q1, is this ESC for an automotive application? How much current do you need to sense at this common mode? There are some ways you can achieve this through isolation or other means, but I'd like to understand your system a bit better here.

  • Hi Carolus, 

    Thanks quick reply!

    I am working on a ~15kW inverter for a 3 phase BLDC motor. (120V, 125A). I would like to do inline phase current measurements, but the voltage is high enough that I fall into an isolated solution. This is leading us to just do a low-side measurement. I would appreciate your opinion for an small isolated solution if you have something to recommend. 

    Thanks again!


  • Jason,

    That amount of current is going to be challenging, even implementing on the low side. The issue here is most of our devices are non-isolated solutions.

    You could look at something like AMC1300.  The measurement inputs top out at 250mV, which means that you could use at most a 2mohm shunt here to get the maximum input FSR. 

    You could look at a digital device like the new INA239, and isolate the I2C lines with something like ISO7842. We have a similar reference design with INA260 that you can reference here

    Alternatively, you could possibly look at a busbar approach for each phase with DRV425, but this approach is typically reserved for industrial applications where vibrations won't be of concern, as sensor placement is paramount to accuracy in the system.

    Let me know if any of these look appealing and I'll see what additional collateral we have I can share. 

  • Hi Carolus, 

    First, thanks again for the feedback. I also appreciate the link to the current sense video library. I will start going through those. 

    The AMC1300 is very interesting, especially since it seems to solve the isolation and in line measurement problem. I will review this more closely. 

    Second, can we talk a bit more about the low side measurements? Where would I start to get into trouble with a pure low side implementation with the INA240? My ADC will be referenced to the same ground as motor ground. 



  • Hello Jason,

    As for the INA240 the common mode input can go all the way down to -4V.  I believe you will see issues when the input goes below that voltage at the inputs of the INA240.