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AMC1301: Can I use AMC1301 for DC current sensing?

Ashik Amin
Prodigy 80 points
Part Number: AMC1301
Other Parts Discussed in Thread: OPA320, , AMC1300, AMC1302, AMC3302

Tool/software:

Hi,

I am trying to design a shunt based DC current sensing circuit using a isolator AMC1301 and OPA320.

There are similar current sensing circuits in TIDA 01541 but those are mostly inverter current sensing.

I am trying to make a similar design for a boost circuit using a shunt resistor before the inductor.

AMC1301 has +/- 250mV input range which translates to +/-2.05V in its isolated side. 

For the boost circuit I need to sense max 40A current and I don't need the negative range. Is there any reference circuit design for isolated DC current sensing?

My base level circuit is following but it seems not working:

Any help will be appreciated.

Ashik

  • 0
    TI__Expert 6425 points

    Hi Ashik,

    Thank you for your question. Yes, the AMC13xx device family can sense DC current. You can use only the positive input range of the device if that's all your application senses. For high currents up to 40A I would recommend the AMC1302 over the AMC1301. The AMC1302 has an input range of +/-50mV and consequently reduces the amount of power dissipated across the shunt resistor for the same full-scale input range. Alternatively, if you would prefer working with a +/-250mV input device, the AMC1300/AMC1300B are newer and higher performance devices than the AMC1301. 

    This evaluation module can serve as a good example for shunt-based current sensing: AMC-AMP-50A-EVM Evaluation board | TI.com

    The user's guide includes sections on how to size the shunt resistor for intended input range and required power dissipation (Section 4.2.1 Shunt Selection Calculations) and outlines a differential to single-ended conversion circuit (Section 2.3.2 Isolated Amplifier Analog Output). Please note the isolated amplifier used in this EVM is the AMC3302, but if you do not need the integrated DC/DC conversion you can alternatively use the AMC1302. 

    What error are you experiencing in your circuit? What are your accuracy requirements or other system requirements you are looking for?

    Best regards,

    Eva

  • 0 in reply to Eva Mason
    Prodigy 80 points

    Thanks Eva,

    I was wondering if I could bias the negative half to a positive value and use the whole range for my sensing.

    Ashik

  • 0 in reply to Ashik Amin
    TI__Expert 6425 points

    Hi Ashik,

    Could I see a schematic of your project? I think it would be acceptable to just use the positive end of the input range. What are your accuracy requirements? Please let me know if you have any questions as you develop your circuit. 

    Best regards,

    Eva