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INA233: Asking for the INA233 schematic and layout review

SHH
Mastermind 31126 points
Part Number: INA233

HI Team,

Would you please help review the INA233 schematic and layout?

INA233 is used for monitoring 19V/26Watt.

BR,

SHH

  • 0
    TI__Mastermind 24075 points

    Hello SHH,

    Thanks for using our forum. What layout program were the layout files created in?  Without knowing this, it is difficult to open those files.  Based on the schematic I see, the INA device is setup to measure roughy -16A to 16A while the nearby fuse would only permit 7A to pass through.  As such, perhaps your customer could increase the shunt resistor to get better resolution since a large portion appears to not be utilized now.  As for the layout you have posted above, I do not see any obvious problems.  I am curious as to where there shunt is as I do not think it is captured in the image above.

  • 0 in reply to Patrick Simmons
    TI__Mastermind 31126 points
    Hi Simmons,
    thanks for help.
    Please uses the PADS viewer for opening the .pcb layout file.
    www.pads.com/.../


    BR,
    SHH
  • 0 in reply to SHH
    TI__Mastermind 24075 points

    Hello SHH,

    Sorry for getting back to you so late on this.  Pads viewer is not our default layout program and I got swamped shortly after the initial posting.  Now that I know where your shunt is, we do see an area for improvement.  If your customer needs high accuracy measurements, we recommend he change the layout to the figure immediately below if it is not too late already.

    The reason for this is illustrated by the figure below.   Because your customer taps into the IN- side of the shunt along the downstream path of the load, he actually is increasing the resistance seen between IN+ and IN-.  This will thereby increase the Vsense voltage detected for a given load and increase the error in is measurement.  As his resistance is in the mili-ohm range his error may still be within tolerance.  However, if his readings appear to be off this would be the first thing we would recommend fixing.