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BhSa_4078721
Level 2
Level 2
10 replies posted 10 questions asked 5 replies posted

Hi,

I want to design a CapSense board using CY8C4246AZI-L445.

The capsense button size will be of 50mm X 50mm.

Will it give smooth touch operation over 30mm glass?

 

Is there any formula or ration which can define the sensitivity on button size Vs overlay thickness?

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1 Solution
Hari
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi @BhSa_4078721 

 

You can achieve this by following the proximity sensor guidelines. You can have a loop sensor (as having a 5x5cm copper filling will increase the parasitic capacitance to the point where the sensitivity will be very poor) and tune it such that the thresholds are set for accurate detection at 3 cm.

Hari_0-1611303333658.png

 

You can see from CapSense design guide AN that the maximum overlay thickness recommended for buttons is 5 mm acrylic:

Hari_1-1611303513271.png

Note that for glass, the maximum would be 16 mm since εr of glass is 8. Hence, a regular button configuration might fail, but proximity loop would be applicable.

 

Best regards, 
Hari

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1 Reply
Hari
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi @BhSa_4078721 

 

You can achieve this by following the proximity sensor guidelines. You can have a loop sensor (as having a 5x5cm copper filling will increase the parasitic capacitance to the point where the sensitivity will be very poor) and tune it such that the thresholds are set for accurate detection at 3 cm.

Hari_0-1611303333658.png

 

You can see from CapSense design guide AN that the maximum overlay thickness recommended for buttons is 5 mm acrylic:

Hari_1-1611303513271.png

Note that for glass, the maximum would be 16 mm since εr of glass is 8. Hence, a regular button configuration might fail, but proximity loop would be applicable.

 

Best regards, 
Hari

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