Hello!
I have FDC2214EVM and would like to sample all 4 channels having the same ground. I.e. all four capacitors have one common terminal.
When I connect in such configuration the sampled readings make no sense for 3 out of 4 sensors.
What do I need to modify in the evaluation board in order to ger proper readings?
Hi Alexander,
Would you please say what is the meaning of "having the same ground"?
As you know each channel of FDC2214 can be used only with one wire connection. For example, when you want to use channel 1 you can connect proximity sensor to IN1A and leave IN1B not connected to anywhere. For more details please take a look at the image below.
If you have more questions about the issue, let us know.
Regards,
Hossein.
Dear Hossein, thank you for your response and suggestion. I will try to setup with single wire sensor per channel.
What I meant originally with "having the same ground for all four sensors" is the following configuration (taken from the TI tech doc):
Note, that I have evaluation kit which presumably has LC circuit in each channel.
Hi Alexander,
If you are using just a copper pad as the sensor, you will not be able to directly connect the sensors to a common ground. If you connect this copper pad to multiple channels, you will ground the sensors and disrupt the FDC2214's normal operation. This is because all channels that are not actively being measured are shorted to ground. However, if your target is grounded, this will essentially create the desired common terminal. If your system allows the use of parallel copper plates, you could connect these to a common ground. In this case, you would connect one plate to INA or INB and ground the other plate.
Also, please note that you do not need to use a single sensor pad for each channel. We refer to this configuration as "single-ended," but we often recommend using a "differential" configuration. You can see both configurations in the figure below.
Regards,
