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MiNe_85951
Level 7
Level 7
Distributor - TED (Japan)
50 likes received 500 replies posted 50 solutions authored

Dear Sirs and Madams,

 

We have a question about implementing an active shield for proximity sensors.

 

Are there any adoption cases using active shields for PSoC4 proximity sensors?

Could you provide us about the size of the sensor, the gap between the sensor and the active shield, the presence or absence of a ground, etc.?

If you have any guidelines for layout of proximity sensor with active shield, could you please share?

 

Regards,

1 Solution
PandaS
Moderator
Moderator
Moderator
100 solutions authored 5 likes given 250 sign-ins

Hi @MiNe_85951 ,

There are two types of Shielding available in MSCv3 devices. One is Active Shielding for high performance applications. Other is passive shielding for low power applications. 

When the sensor has no ground hatch around it, only the sensor. It usually shows better proximity distance as the EMF lines spread better. But it is susceptible to external noise which can cause false detection.

Ground usually solve the noise issue but increases the Cp of the sensor and causes coupling of EMF lines. This reduces proximity distance.

Shield signal reduces this coupling and brings down Cp. So, you would see some improvements with proximity distance.

I understand that you are designing your own PCB, could you please tell me the stack up? 

Thanks and regards,

Sobhit

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6 Replies
RyanZhao
Moderator
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Moderator
250 sign-ins First question asked 750 replies posted

Hi @MiNe_85951 san

I guess the "active shield" means the "shield enabled", right? Once shield is enabled on configuration, the shield is active.

When shield is enabled, the proximity distance will be similar with the case of no shield or no ground, but it will be much better than the case of presence of ground.

About a proximity sensor's design, please see AN92239 proximity sensing with CAPSENSE™ and the proximity sensing section in Getting started with CAPSENSE™ design guide to learn more about proximity sensors.

Best Regards, Ryan

MiNe_85951
Level 7
Level 7
Distributor - TED (Japan)
50 likes received 500 replies posted 50 solutions authored

Ryan-san,

 

Active Shield means to set Shield mode to Active.

MiNe_85951_0-1692667895107.png

 

Please tell us about your answer below:

/*********************************************************************************************************/

When shield is enabled, the proximity distance will be similar with the case of no shield or no ground, but it will be much better than the case of presence of ground.

/*********************************************************************************************************/

MiNe_85951_0-1692670748849.png

Detection distance: (c) ≒  (a) > (b)
I understand the above.
What are the advantages of using (c) over (a)?

 

Regards,

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PandaS
Moderator
Moderator
Moderator
100 solutions authored 5 likes given 250 sign-ins

Hi @MiNe_85951 ,

There are two types of Shielding available in MSCv3 devices. One is Active Shielding for high performance applications. Other is passive shielding for low power applications. 

When the sensor has no ground hatch around it, only the sensor. It usually shows better proximity distance as the EMF lines spread better. But it is susceptible to external noise which can cause false detection.

Ground usually solve the noise issue but increases the Cp of the sensor and causes coupling of EMF lines. This reduces proximity distance.

Shield signal reduces this coupling and brings down Cp. So, you would see some improvements with proximity distance.

I understand that you are designing your own PCB, could you please tell me the stack up? 

Thanks and regards,

Sobhit

PandaS
Moderator
Moderator
Moderator
100 solutions authored 5 likes given 250 sign-ins

Hi @MiNe_85951 ,

The distance between ground hatch and Proximity sensor should be 1mm minimum, as per standard guidelines. Same applies to shield as well.

Thanks and regards,

Sobhit

MiNe_85951
Level 7
Level 7
Distributor - TED (Japan)
50 likes received 500 replies posted 50 solutions authored

Unlike buttons and sliders, there seems to be little information about layout guidelines such as proximity sensor size.

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PandaS
Moderator
Moderator
Moderator
100 solutions authored 5 likes given 250 sign-ins

Hi @MiNe_85951 ,

Thankyou for your inputs, working on a Knowledge Article for Proximity based applications. To be released soon.

Thanks and regards,

Sobhit

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