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CURRENT SENSE APPLICATION

WILLIE MCCAIN
Prodigy 235 points
Other Parts Discussed in Thread: TIDA-00332, INA285

ON THE PART NUMBER INA285AID I WONT TO USE THE PART IN A CURRENT SENSE APPLICATION BUT THE PART IS LIMITED TO THE COMMON MODE RANGE I NEED TO NO IF I CAN ADD INPUT RESISTORS ON BOTH INPUT LIKE ADD 1 MEG OHM AT .025% TOL. SO I CAN SENSE THE CURRENT AT 400 VDC BUS SENSE AND ONE IN THE SOURCE LEAD OF THE POWER MOSFET TO MEASURE THE CURRENT AS WELL ...................

ARE WOULD I USE A H-VOLTAGE DIVIDER TO GET TO THE LETS SAY 50 VDC RANGE AND THAN APPLY THAT TO THE INPUTS OF THE PART TO READ THE CURRENT IN THE HI-SIDE AND JUST USE THE COMMON PART FOR THE SOURCE CURRENT SENSE.......................

LET ME NO THANKS FOR YOUR HELP

  • 0
    TI__Mastermind 25775 points
    Hello Willie,

    I have moved your post to the Current Sensing Forum for further support.
  • 0
    TI__Mastermind 18780 points

    Dear Willie,

    We typically recommend that resistors placed in line with the IN+ and IN- be less than 10 ohms for the purposes of filtration only, as too much resistance in the path will add significant gain error to the system, rendering the measurement worthless.

    For your application, I would suggest implementing a low side measurement. If you place the shunt beyond the load, then you will not need to worry about the 400 VDC being passed across the shunt, and your Vcm across the shunt will be approximately zero. Have a look at these videos to show you how to implement on the low side.

    e2e.ti.com/.../467332

    Videos 1-3 discuss at length the difference between high and low side implemenations, and you can also delve into how to control the error in your system. Let me know if you need anything else.

    Sincerely,

    Carolus

  • 0 in reply to Carolus Andrews
    TI__Genius 14825 points

    Willie,


    You might also look into this TI Design that can put the common mode up to 400V, but not with the INA285.  TIDA-00332

    Best regards,