VREF voltage of PSoC4000S CapSense Component

[YoIs_1298666]

Hello,

We know that the vref voltage of PSoC4000S CapSense Component depends on the VDDA voltage in Electrical Specifications of

the CapSense component datasheet and KBA220609.

If the VDDA changes the voltage from +3.3V to +2.6V, does the vref voltage follow the VDDA from  2.021V to 1.477V ?

Or It does not follow the VDDA because it is set the voltage when the CapSense_Start() function is done.

Which is correct?

Best regards,

Yocchi

[BrandonP_16 · Accepted solution]

Hi Yocchi,

The Vref value is determined when you build the firmware.

CapSense component refers the VDDA value which is set by System tap in .cydwr in PSoC Creator project file.

So, CapSense does not follow the measured VDDA in run-time, but fixes the Vref value with your input.

Thanks,

Brandon

[YoIs_1298666]

Hello Brandon-san,

Thank you very much for your quick response.

If the VDDA is +3.3V but System tap's VDDA is set to +1.8V like below.

Is the real vref  1.2V?

If it is correct, the VDDA is +1.8V but System tap's VDDA is seto to +3.3V, how something will end up？

Best regards,

Ishii

[Vison_Zhang]

If VDDA is +3.3V but System tap's VDDA is set to +1.8V, real vref is 1.2V.

If VDDA is +1.8V but System tap's VDDA is set to +3.3V, the calculated vref=2V, real vref is can only reach 1.5V~1.6V, but this setting way is wrong, please don't do that at any time.