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INA233: Question of Input Filtering Schematic in INA233 Datasheet

Wayne Chen (ex FAE)
Guru 15950 points
Part Number: INA233

Hi Sirs,

Would you please advise if there is mussing of Rfilter symbol at IN- in input filtering reference design on INA233 datasheet page 15? 


Thank you and Best regards,

Wayne Chen
06/17/2019

  • 0
    TI__Mastermind 27715 points

    Hi Wayne,

    It does look like there is a missing resistor at the IN- pin in order to create the usual recommended differential filter. Peter Iliya on our apps team will follow up tomorrow when we return to the office.

    Best regards,

    Ian Williams
    Applications Manager
    Current & Magnetic Sensing

  • 0
    TI__Mastermind 26650 points

    Hey Wayne,

    There definitely is a Rfilter resistor symbol missing in Figure 25. It is best practice to use two 10-Ohm input resistors for each input pin since this will not only decrease the cut-off frequency of the differential filtering, but it also minimize the error added by the resistors. If only one 10-Ohm resistor is used, then an immediate offset would be generated with (IB+)*10 Ohms. However, if two resistors are used and IB+ = IB- = 8uA, then the voltage drops across both resistor will approximately be the same depending on resistor tolerance and they will cancel out.

    Sorry for the incomplete Figure. We will work to correct this.

    Best,

    Peter

  • 0 in reply to Peter Iliya
    Guru 15950 points

    Hello Peter, Thank you for your confirmation...Wayne Chen