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MSP CapTIvate with 6mm Acrylic Overlay

Paul Bryson
Intellectual 490 points

Other Parts Discussed in Thread: CAPTIVATE-PHONE, CAPTIVATE-PGMR, CAPTIVATE-FR2633, CAPTIVATE-BSWP

Application Notes for the CapTIvate technology mention acrylic overlays of 1mm-3mm and say thinner is better.

In my application I would really like to use a 6mm acrylic overlay.

Is this practical?

What problems/limitations might I encounter?

  • 0
    TI__Expert 5490 points
    Hello Paul,

    It really depends on your electrode layout and mechanical design.
    It is possible to achieve 6mm acrylic overlay for a touch button application but it depends on your design and applications.
    1. Electrode area: make sure the electrode size is slightly larger than the finger tip area.
    2. Mechanical design: make sure there is no any air gap between the overlay and sensor PCB.
    3. Parasitic capacitance loading: if you expect your design to operate with line power and under intense conductive noise or RF noise then you will need to have pretty good ground shielding around the sensor however more ground shielding means more parastitic capacitance loading to the sensor which means lower sensitivity to touch.
    4. System noise: higher sensitivity to touch also means higher sensitivity to any noise in the system so you also need to consider the noise in the system.

    Here are two app notes for your reference.
    www.ti.com/.../slaa842.pdf
    www.ti.com/.../slaa843a.pdf

    You can always get our evaluation board and test your sensor design.
    www.ti.com/.../CAPTIVATE-FR2633

    CAPT-FR2633-BNDL:
    CAPTIVATE-FR2633 + CAPTIVATE-BSWP + CAPTIVATE-PHONE + CAPTIVATE-PGMR bundle

    Thanks,
    Yiding

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