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PSoC™ 4

ViWa_4121741
New Contributor II

Hi,

First of all congratulations for your community.

I would like to know how to define every part in my layout. I have a seven segments linear slider surrounded for a proximity sensor. My question is:

Q1: I found in the design guidelines that two more GND segments should be added at the beginning and at the end of the slider, is it necessary if I add a GND hatched plane? If the hatched plane is used for the shield electrode is necessary these GND segments? (I will implement two mount/no mount  0ohms resistors to have both options)

Q2: I found that the proximity sensor needs a ground loop around, but i didn't found anything about the inside of the proximity. In my case, the slider will be inside the proximity sensor, so the hatched plane (SH or GND) of the slider could interfere with the proximity sensor?

Have any advice to create the layout with both solutions would be great,

Thank you

Victor

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1 Solution
Hari
Moderator
Moderator

Hi viwa_4121741

1. It is recommended to add two more dummy segments at top and bottom to obtain a linear response from the slider. The connection to these segments depends on the inactive sensor configuration of the CapSense component.

pastedImage_0.png

If this is selected as ground, the dummy segments must be connected to ground.

2. It is recommended to use shield inside the proximity sensor as this will result in lower parasitic capacitance and therefore, better sensitivity.

Please refer Proximity Sensing with CapSense for more details on design.

Thanks and regards

Harigovind

View solution in original post

7 Replies
Hari
Moderator
Moderator

Hi viwa_4121741

1. It is recommended to add two more dummy segments at top and bottom to obtain a linear response from the slider. The connection to these segments depends on the inactive sensor configuration of the CapSense component.

pastedImage_0.png

If this is selected as ground, the dummy segments must be connected to ground.

2. It is recommended to use shield inside the proximity sensor as this will result in lower parasitic capacitance and therefore, better sensitivity.

Please refer Proximity Sensing with CapSense for more details on design.

Thanks and regards

Harigovind

View solution in original post

ViWa_4121741
New Contributor II

Hi,

Thanks for your response, so what i understood is that is recommended two dummy segments connected to GND to increase the slider linearity, a hatched shield inside the proximity sensor around the slider (including the dummy segments), and a GND loop around the slider.

Is okay something like that?

IMG-8011.JPG

Best regards,

Victor.

Hari
Moderator
Moderator

Hi

Yes this is the correct implementation of slider and proximity. The only clarification is that ground loop must be around proximity, not slider

Best regards

Harigovind

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ViWa_4121741
New Contributor II

Yes, typo mistake.

There is any kind of rule to place components or planes around the proximity sensor ground loop?

In mid layers (i will use a 4 layers stack up) can i use vdd or gnd solid planes or is recommended to use always hatched patterns.

My stack up will be something like this:

TOP->slider+prox+hatched1 (shield)

MID1-> hatched2/solid (gnd plane)

MID2->vdd+signals (gnd plane)

BOT-> CY9MBR3106s + hacthed/solid (gnd plane)

Signals can be at adjacent layers of sensors or is preferable to separate it.

Thank you for your help,

Victor

Hari
Moderator
Moderator

Hi

In the second layer, it is recommended to use shield hatch and ground in bottom layer to reduce parasitic capacitance, thereby increasing sensitivity.

A solid ground is not suggested right below the sensor as this will increase the parasitic capacitance. It is alright to include solid ground away from the sensor.

So the correct stack up is

TOP->slider+prox+hatched1 (shield)

MID1-> hatched shield

MID2->vdd+signals (gnd plane) (use hatched ground in areas beneath the sensor)

BOT-> CY9MBR3106s + hacthed/solid (gnd plane)

Thanks and regards

Harigovind

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ViWa_4121741
New Contributor II

I found this in the AN90071:

pastedImage_0.png

Are two ways correct?

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Hari
Moderator
Moderator

Hi

Yes, this is also correct, but for liquid level tolerance, the way suggested above is correct. Please refer AN85951

pastedImage_0.png

Thanks and regards

Harigovind

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