Why should the ground around the capsense be meshed?

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
kain_4812361
Level 1
Level 1
5 questions asked 5 sign-ins First reply posted

Hello. This time, I have a question during the CapSense Study.

Why should I Hatch Ground when designing Capsense?

What are the advantages of hatch processing?

I don't know if I read the CapSense Getting Start and Schematic documentation...

CapSense.jpg

0 Likes
1 Solution
BragadeeshV
Moderator
Moderator
Moderator
First question asked 1000 replies posted 750 replies posted

Hi kain_4812361​,

The parasitic capacitance of the sensor, Cp, affects the sensitivity, scan time and power consumption. Higher the Cp of the sensor, lower  is the sensitivity, higher is the scan time, and higher is the power consumption. Solid ground around the sensors would lead to high Cp due to more coupling to ground. However, ground around the sensors provide return path for noise and hence required for passing EMI/ EMC / ESD standards. Therefore, to reduce Cp and still have good noise immunity, we recommend using hatch ground (only near and below the sensor area)  so that coupling of sensor to ground is less and hence Cp is less. Other areas of the PCB not closer to the sensors can have solid ground pour.

Regards,

Bragadeesh

Regards,
Bragadeesh

View solution in original post

3 Replies
BragadeeshV
Moderator
Moderator
Moderator
First question asked 1000 replies posted 750 replies posted

Hi kain_4812361​,

The parasitic capacitance of the sensor, Cp, affects the sensitivity, scan time and power consumption. Higher the Cp of the sensor, lower  is the sensitivity, higher is the scan time, and higher is the power consumption. Solid ground around the sensors would lead to high Cp due to more coupling to ground. However, ground around the sensors provide return path for noise and hence required for passing EMI/ EMC / ESD standards. Therefore, to reduce Cp and still have good noise immunity, we recommend using hatch ground (only near and below the sensor area)  so that coupling of sensor to ground is less and hence Cp is less. Other areas of the PCB not closer to the sensors can have solid ground pour.

Regards,

Bragadeesh

Regards,
Bragadeesh

Thank you! In addition, can it be configured with Solid Ground instead of Hatch Ground? If not, can you see why?

0 Likes

I'm sorry..

In the answer, I told you the difference between Solid Ground and Hatch Ground, but I misunderstood it.

Thank you for answer!

0 Likes