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DRV425: Drift over time

Michael Sorenson
Prodigy 10 points

Part Number: DRV425

I am using an array of six DRV425 devices, separated by about 1cm each, in a sensor design.  During calibration in a 'zero gauss' chamber I am noticing a slow but steady drift over time (continues for at least days).  Does anyone have any ideas why there would be drift?  Some of the sensors drift in a positive direction and some in a negative direction.  I initially thought it might be temperature, but I have a thermistor next to each DRV425 and am monitoring those at the same time and they stabilize relatively quickly.  I have also monitored the power supply voltage and found it to not be drifting over time. 

I am using a 24-bit ADC, sampling a few times per second and then transmitting the average of those samples once per second.

Thanks in advance for any help.

  • 0
    TI__Genius 15770 points

    Hi Michael,

    Thanks for using TI E2E forums. We are going to forward your question to our magnetic sensor apps engineer. He will get back to you soon. In the meantime, can you share your schematic or a block diagram of your system?

    Thanks

  • 0
    TI__Mastermind 33550 points
    Michael,

    I would be happy to help find the root cause of this drift. I have a few questions that would help me understand or narrow it down. Do you measure your output with respect to your Vref pin? In other words do you measure differential between Vout and Vref with your ADC? If not, can you verify this does fixes the issue? What shunt resistor value are you using? Could this resistor shift as well. By drift can you give me a voltage or magnetic field value that you see it drifting? Are you applying an external magnetic field at all or measuring zero field. If you are forcing a field is there a way to make sure the source is not drifting?
  • 0 in reply to Javier Contreras4
    TI__Mastermind 33550 points
    This thread has gone offline. Looking for the root cause of the drift.