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FDC2114: Data for smaller Sensor Area

Prodigy 40 points

Replies: 7

Views: 217

Part Number: FDC2114

Hello

I have comfirmed the doc (SNOA940A)

http://www.ti.com/lit/an/snoa940a/snoa940a.pdf

But I would like to know smaller sensor size.

required detection distance : 10cm approx

assumed sensor size : 5 mm x ___mm   (GND size is same.)

distance between sensor and GND : 1.0mm

Could you let me know the length of the sensor size?

I cannot read from the graph(Fig.3) due to the range.

Thank you

Best regards,

  • Hello,

    I don't have the exact datapoint on the graph, but you should be able to achieve a 10cm sensing distance with an electrode that is roughly 1cm x 1cm, perhaps a bit larger. You may need a larger sensor depending on the size of your target and your noise floor.

    Also please note that we do not recommend placing a ground plane or grounded object near the sensor electrode, as this will significantly decrease the sensitivity.

    Best Regards,

    Kristin Jones

    Battery Automotive Products

    Applications Engineer


  • In reply to Kristin Jones93:

    Hello

    Thank you for your answer.

    My understanding is that the are is important, so that 1cm x 1cm equivalent to 0.5cm x 2 cm, correct?

    Also thank you for the advice, but from the structural restrictions, we need to place the frame near the sensor.  It is Digital Ground.

    At that case, to compensate the decreasing sensivity, we might need to increase the sensor size, correct?

    (note: the GND electrode underneath of the sensor is not counted as the cause of sensitivity reduction??)

    Thanks

  • In reply to Masaharu Matsumoto:

    Hello,

    Yes, it is the overall sensor area that is important, so 0.5cm x 2cm would be an equivalent sensor.

    Increasing the sensor size will increase the sensitivity, but this may not be enough to overcome nearby capacitance to GND if it is very high. 

    Could you clarify what you meant by the GND electrode? You should not have a separate GND electrode.

    Best Regards,

    Kristin Jones

    Battery Automotive Products

    Applications Engineer


  • In reply to Kristin Jones93:

    Hello,

    I haven't heard from you in a while, so I'm assuming you were able to resolve your issue. If this is not the case please feel free to reply to this thread or post a new question.

    Best Regards,

    Kristin Jones

    Battery Automotive Products

    Applications Engineer


  • In reply to Kristin Jones93:

    Hello

    sorry Maybe I made mistake, I feel like I saw GND electronde underneath of the sensor electrode....

    But I could not find what I have seen... sorry.

    Could you please let me know the page where I can simulate the relationship between sensor area and sensing distance?

    I think there was two area to fill for the sensor area.

    Thank you

    Best regards,

    Masaharu Matsumoto

  • In reply to Masaharu Matsumoto:

    Hello Matsumoto-san,

    You can use FEMM to simulate electrostatic problems. It's open-source software available here, and there are guides for electrostatic problems. If you are trying to sense the presence of a human, I suggest using a large water target in the simulation.

    You may have seen some documentation which shows a shield electrode layered with the sensor electrode. This is only for the FDC1004, which has an active shield driver, unlike the FDC2214.

    Best Regards,

    Kristin Jones

    Battery Automotive Products

    Applications Engineer


  • In reply to Kristin Jones93:

    Hello Kristine san,

    Thank you so much for both simulation software and the FDC1004.

    I'm going to play with simulator.

    Thank you for your support

    Best regards,

    Masaharu Matsumoto

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