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fluxgate sensor for nT measurements

Steve Jarvis
Intellectual 575 points
Other Parts Discussed in Thread: DRV425

Hi,

we have to measure earth's magnetic field and other magnetic fields from 100 nT to 100 uT and from DC to 100Hz. 

What are the suggested sensors?

The only TI fluxgate parts we could find show mT ranges BUT in the TI's video linked below the TI engineer mentions TI fluxgate sensors are the most sensitive in the world and can measure nT magnetic fields (see video at 33:25): https://training.ti.com/webinar-jump-start-your-hall-effect-sensor-expertise-0?keyMatch=nanotesla&tisearch=Search-EN-Everything 

  • 0
    TI__Mastermind 26505 points

    Rick,

    Please take a look at the DRV425 device.  You may need to sample or filter the noise to get to the 100 nT level accuracy.  You can order the DRV425EVM add experiment with it.  Please let me know if you need any additional help in evaluating the DRV425 or have any questions about this device.

  • 0 in reply to Javier Contreras4
    Intellectual 575 points

    Thank you Javier,

    we ordered the EVM kit.

    Does the DRV425 require any type of calibration?

    If so, is the DEV KIT already calibrated or not?

    Many thanks

    Rick

  • 0 in reply to Steve Jarvis
    TI__Mastermind 26505 points

    Rick,

    The DRV425 will meet the specifications of the datasheet without calibrations.  The offset is 8uT max and the output should be measured with respect to Vref.  From your previous question you may need to worry about noise and either filter or increase you sample integration. 

    The earth's magnetic field should be around 60uT-70uT so depending on the orientation of the DRV425 you may measure the field positive, negative or none at all.  If you would like to shied the earth's magnetic fields or any other stray magnetic fields you will need to place a material that is magnetic around it.

    The placement on the datasheet shows the location of the sensor relative to the package and has a tolerance in 0.025 mm or 0.001 inch.   You can use simulation software to calculate the field either from a magnet or another source.    If you need more information or have other concerns please let me know.  If you can share with me your application it may be easier to determine how else I can help.  The datasheet is a good resource and we have some other documents on the DRV425 product page.