fdc1004: Liquid level sensing Reference channel not accurate

Sai Loo

Part Number: FDC1004
Other Parts Discussed in Thread: TIDA-00317

Hi Team,

My customer is modifying FDC1004EVM for liquid level sensing according to TIDA-00317 reference design. The sensitivity is as good as the application note. However, the RL shows a significant difference from the note, as you can see in the chart below and the record attached. Do you have any idea why the difference here?

Configuration of FDC1004EVM is single-end measurement:

· MEAS1 CHA: CH1

· MEAS1 CHB: DISABLE

· MEAS2 CHA: CH2

· MEAS2 CHB: DISABLE

· MEAS3 CHA: CH3

· MEAS3 CHB: DISABLE

over 7 years ago

0 Chris Oberhauser66 over 7 years ago

TI__Genius 14270 points

Hello Sai,

Did you include the shield connections as shown in figure 6 of the reference guide?

Regards,

ChrisO

0 Sai Loo over 7 years ago in reply to Chris Oberhauser66

TI__Expert 5100 points

Hello Chris,

They had modify the wire into a flex PCB with the proper shield as shown below. They get better accuracy with this setup than the previously attached with wire connection and the data is actually captured with this setup.

0 Chris Oberhauser66 over 7 years ago in reply to Sai Loo

TI__Genius 14270 points

Hello Sai,

If I understand you correctly, then the graph you showed in the beginning was collected on the setup shown in the second picture?

ChrisO

0 Sai Loo over 7 years ago in reply to Chris Oberhauser66

TI__Expert 5100 points

Hi Chris
Yes, The graph curve data is collected with the setup using the flex PCB using TIDA-00317 layout.

0 Chris Oberhauser66 over 7 years ago in reply to Sai Loo

TI__Genius 14270 points

Hello Sai,

Thank you for your response. The response you have there is strange - the liquid env sensor should not peak as you are seeing. Perhaps there is something on the container that is affecting the response?

ChrisO

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fdc1004: Liquid level sensing Reference channel not accurate