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Circuit help

sanjeev kumar87916
Intellectual 660 points

Other Parts Discussed in Thread: INA114, TINA-TI, ADS1147, ADS7870

Hi all,

Can any one give me the information that in that following circuit why we are using Resistor "R5" And "R6" Is it pullup /Pulldown resistor or something else.

Thanks And BR

sanjeev

  • 0
    TI__Mastermind 25865 points

    Hello Sanjeev,

    Those resistors are used to limit the current through the Wheatstone bridge, set the common-mode voltage to 2.5V (when RTD=100ohms), and limit the differential input voltage.  Please see the attached TINA-TI schematic and simulations for further understanding.  You will notice the INA114 will saturate quickly without R5 and R6.

    Another note is that with dual supplies (+/-15V) the INA114 can output +/-13.7V (typical).  The ADS7870 is a 5V ADC.  Be sure to protect the input of the ADC if this is the desired solution.  An alternate option would be to consider our ADS1147.

    wb.TSC
  • 0 in reply to Pete%20Semig
    Intellectual 660 points

    Thanks Pete for the suggestion i will go through, i think this is useful for me.

    BR

    Sanjeev