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PSoC 4 MCU

almc_4008691
New Contributor II

Hello,

I'm designing a proximity sensor on a pcb.

The first design I have got is 4 sensors pads ( 20mm*20mm) next to each other and they are used as a proximity sensing which is working ok.

But I wanted to try with a loop trace on the pcb instead of pads which are normally for touching and not proximity sensing?!

Therefore, I wanted to add some hatch pattern on the top and bottom layer ( 2 layers pcb).

Do I need to put a hatch inside the loop?

Also I'm close to a metallic object so which signal should I drive on the top and bottom layer? I'm a bit lost between shield or ground?

Thanks in advance for your time,

Alex

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1 Solution
Vison_Zhang
Moderator
Moderator

The width of proximity ring should be at least 2mm width, you can use 2mm if the PCB space is enough. Your proximity sensor is close to a metallic object, i recommend you use shield hatch around and behind the proximity ring. Shield hatch should connect to an shield pin through a series R also, but 100 ohm is enough, not need 560 ohm.

Shield hatch just need to be laid inside the proximity ring and nearby the ring, don't need to be cover entire PCB.

View solution in original post

5 Replies
ShanmathiN_06
Employee

Hi Alex,

Could you pls attach the image again?

However, you could refer to the Proximity Sensing AN: https://www.cypress.com/documentation/application-notes/an92239-proximity-sensing-capsense to refer on the layout guidelines to design proximity loop sensors.

Thanks,
Shanmathi

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almc_4008691
New Contributor II

hello

here it is :

Capture.PNG

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Vison_Zhang
Moderator
Moderator

The width of proximity ring should be at least 2mm width, you can use 2mm if the PCB space is enough. Your proximity sensor is close to a metallic object, i recommend you use shield hatch around and behind the proximity ring. Shield hatch should connect to an shield pin through a series R also, but 100 ohm is enough, not need 560 ohm.

Shield hatch just need to be laid inside the proximity ring and nearby the ring, don't need to be cover entire PCB.

View solution in original post

almc_4008691
New Contributor II

Capture2.PNG

That's my second design and I want to know if it's better the loop or that design for a proximity sensing.

I think the loop but I wanted to be sure !

Thank you so much

Alex

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ShanmathiN_06
Employee

Hi Alex,

Please use a wire loop for better proximity distance. You can refer to Table 1 of https://www.cypress.com/file/46741/download

to decide on selecting a proximity sensor type.

Also, you could refer to Section: Nearby floating or grounded conductive objects of https://www.cypress.com/file/41076/download to check on the shield hatch layout guidelines.

Thanks,
Shanmathi

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