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FDC1004EVM: FDC1004EVM

Md Nazmul Imran
Prodigy 30 points
Part Number: FDC1004EVM
Other Parts Discussed in Thread: FDC1004, MSP430F5528

1) What is the input (driving) voltage my sensor will get if I connect the USB of FDC1004EVM with the computer and connect my sensor with CINx and GND of the FDC1004? Is it DC voltage or AC. What's the frequency if AC and can I change the input voltage frequency?

2) My sensor is giving more capacitance than the 15 pF limit. So I have changed the gain (in the calibration) to 0.5. Now, if the actual capacitance 20 pF, with the change of gain (0.5) the capacitance will become 10 pF. Is it right?

Thank you.

Best Regards,

Nazmul Imran

  • 0
    TI__Expert 7599 points

    Hello,

    Our Apps engineer is on a spring break Holiday. We will get back to you next week. 

    On the question 1 ? Can you please help us provide more information on your observations ? Can you share with us your plots and setup ?

  • 0 in reply to Arjun_Prakash
    Prodigy 30 points

    Thank you, Mr. Arjun

    Basically, I have replaced the third section which is a touchless sensor with fabricated Interdigital Capacitive Sensor (IDC). I have connected the first section (which is a USB to I2C converter based on MSP430F5528 microcontroller) to a computer USB port. The second section (FDC1004) is kept as it is. This IDC sensor measures the permittivity change in insulation material, say for Air capacitance is 2 pF and for FR4_Epoxy capacitance is 5 pF. 

    My question was on the output voltage type of the second section (FDC1004) which is the input of my sensor? My sensor has three ports that are connected to the CIN1, GND, and Shield1 ports of FDC1004EVM.

    Thank you.

  • 0 in reply to Md Nazmul Imran
    TI__Expert 3435 points

    Hi,

    Please find my answeres below

    1. Please find the Excitation section of the datasheet. 

    2. I would recommend using the Offset feature to add an offset so that the total capacitance is below 15pf. LDC1004 has a maximum offset capacitance up to 100 pf

    Regards

    Sharath.