• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 709 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

FDC2112: Confusion about electrode design

Karlis Tucs
Prodigy 50 points
Part Number: FDC2112

Hi. I am completely new to this segment of electronics and I got little bit confused.

In my device the surface area of sensing should be around 30 x 30 cm.

I was reading http://www.ti.com/lit/ds/symlink/fdc2212-q1.pdf  and http://www.ti.com/lit/an/slaa576a/slaa576a.pdf  and could not understand which option is better.

In first datasheet it is said that there only must be 1 plate of sensor, and the orther "plate" will be formed by human - and thus a variable capacitance will be created. 

In the application note(second PDF) it is written that variable capacitor is made of sensor plane and ground plane underneath it...And human just changes the dielectric permeability of this capacitor by putting hand near it.

So what way I should make the electrode of 30 x 30 cm area - the first or the second option? I plan to use FDC2112.

Best regards,

Karlis Tucs

  • 0
    TI__Genius 11340 points

    Hi Karlis,

    For touch applications with FDC2112, each channel will have one sensor plate (in your case, the 30 x 30 cm electrode). This sensor plate is made of a conductive material (and a lot of times, as mentioned in the second document, it is the copper on the PCB).  As a human hand approaches the sensor, it creates a capacitive path to ground, thereby increasing the total capacitance of the system.

    In both options you described, there's only one sensor per channel. 

    Best,

    Jiashow