• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 47 subscribers
  • Views 1195 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMP90100 for (multiple) strain gauge measurement

Patrick Pelgrims
Prodigy 10 points
Other Parts Discussed in Thread: LMP90100

Dear,

I world like to measure multiple strain gauges (1KOhm/5KOhm versions).

Due to the applyed 1000 micro strain I expect only 10 Ohm deviation in resistance value.

How schould I connect those strain gauges with the lmp90100 to measure these deviation with the

highest resolution als possible ?

Hoping to recidive some usefull reaction.

Kind Renards,

Patrick

  • 0
    TI__Intellectual 2065 points

    Hi Patrick,

    You can have the strain gauge connected in bridge configuration and measure the differential voltage. LMP90100 provides max Gain of 128 and also an Input Buffer.

    Is the Max deviation 10 Ohm?

    Regards,
    Murali 

  • 0 in reply to MS1291
    Prodigy 10 points

    Hello Murali,

    I should use 5 KOhm strain gauges to lower power consumption.

    The application measure about 1000 µStrain and with a Gauge factor of 2.05 the change in resistance

    of the gauge is about 2.05*5E3*1000E-6 = 10 Ohms.

    Due to place limitationsan I can only place three strain gauges to measure strain at three different locations.

    So I can not use full Wheatstone bridge configuration and I do not prefer half bridge (one stressless strain gauge)

    since it devides the output signal by a factor 2.

    I was thinking to use one current source driving a precision reference resistor and use the second current source

    driving the strain gauge. Supposing both current sources are matched ones It should be possible to measure

    the difference between the voltage over the strain gauge and reference resistor.

    Using 500 µAmp currents in a 5 Volt powered system the common mode voltage is about 2.5 V

    and the 10 Ohm change will generate 5000 µV or 5 mV.

    What are you thinking about this idea not yet taking into account the strain gauge tollerances

    since I can calibrate for 1% changes.

    Hoping to discuss this further.

    Greetings,

     

    Patrick