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DRV425: DRV425

Part Number: DRV425
Other Parts Discussed in Thread: ADS1248

To whom this may concern,

I am using the DRV425 Fluxgate Magnetic-Field sensor and I am having a small issue with the reference voltage output.

On page 15 of the revised March 2018 data sheet figure 52 shows the Reference voltage versus reference current.  This shows a stable voltage whether sinking or sourcing up to 5 mA.

In my application, with a PSU of 5 V and RSEL 00, when I apply a 1 kohm load to REFOUT the measured voltage is only 2.2 V.  This only returns within the +/- 50 mV specification when the load is > 10 kohm.

Can you offer some advice?  I look forward to your response.

Regards

James

  • Hello James,

    I would not expect any issue with driving 1KΩ. Could you please tell me if you have a capacitor on that node? If so you may want to remove it as this cannot drive a high capacitance value.
  • James,

    You have not replied back. I will assume your issue was resolved. I will close the post. If you have yet to resolve the issue simply reply in next couple of days or start a new post.
  • Hello Javier, I may be running into a similar problem. 

    I am connecting the DRV425EMV vout pin to the ADS1248EVM to create a data acquisition system for prototyping.  So the DRV425 is driving 47pF common mode and 0.1uF differentially, see below.  Should I remove the 0.1uF?


  • Eduardo,

    Thanks for using the E2E to get your design questions answered.

    Is the DRV425 Reference driving the capacitance without an isolation resistor. I will assume you are connecting the reference voltage to R15. The DRV425 reference is not designed to drive a large capacitance. Two thing that can help is lower the capacitance and place a resistor of about 200 Ω or 1KΩ I am not sure if the ADS1248 will have issues with either of those two options.

    Another option is to drive the Reference Input pin with the ADS1248 reference pin.

    Please let me know if this solves your issue.