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PSoC 6 MCU

Contributor

Hi, I could not find recommendations for copper weight with capsense. Is anything other than 1oz good?
I was thinking I could use 0.5 oz, which enables the factory I am targeting to produce 4mil trace width, which according to the capsense design guideline is a good thing

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*there is no minimum width at all? wouldn't there be too much current for the trace width at one point?

Thanks!

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Moderator
Moderator

Hi JeSi_4326976​,

1. The weight of copper for the sensor pads do not contribute much to the performance of CapSense. We are only concerned about the Cp formed at the end that determines the sensitivity.

2. We do not have any recommendations on the minimum trace width on CapSense sensors. However, we have seen designs with 4 mil trace width working well and therefore this should not be an issue. There are two points to consider when using thin traces:

a. Low Cp -> Implies high sensitivity and low power consumption

b. High R -> Reduces the sense clock/ Tx Clock. But the impact on this might not be seen much unless it is a very long trace.

Regards,

Bragadeesh

Regards,
Bragadeesh

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3 Replies
Moderator
Moderator

Hi JeSi_4326976​,

1. The weight of copper for the sensor pads do not contribute much to the performance of CapSense. We are only concerned about the Cp formed at the end that determines the sensitivity.

2. We do not have any recommendations on the minimum trace width on CapSense sensors. However, we have seen designs with 4 mil trace width working well and therefore this should not be an issue. There are two points to consider when using thin traces:

a. Low Cp -> Implies high sensitivity and low power consumption

b. High R -> Reduces the sense clock/ Tx Clock. But the impact on this might not be seen much unless it is a very long trace.

Regards,

Bragadeesh

Regards,
Bragadeesh

View solution in original post

Contributor

Thank you for the clear and complete response BragadeeshV_41

BragadeeshV_41 wrote:

a. Low Cp -> Implies high sensitivity and low power consumption

That means there aren't any real advantages to reducing trace width with CSX since this method is immune to self Cp of capsense lines?

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Moderator
Moderator

Hi JeSi_4326976​,

That is correct. CSX technique is particularly used when the CP of the buttons is very high. In CSX technique, the raw counts/ signal is dependent only on the Cm between the two segments and is independent of the Cp of the individual segments.

Regards,

Bragadeesh

Regards,
Bragadeesh
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