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FDC2214: FDC2214 integrated circuit being on the stack

Mesut Can Yaman
Prodigy 50 points
Part Number: FDC2214


Hello,

I am using the FDC2214 device for a liquid level measurement application. I am operating two channels of the device (CH0 and CH1) to measure the liquid levels in two separate containers. When I run a single channel, the system operates without any issues; however, when both channels are enabled simultaneously, the data ready flag stops being asserted after approximately 5–10 seconds. In this condition, even if the liquid level changes, I cannot receive data from either channel.

I initially suspected that the issue might be caused by a long conversion time, so I modified the RCOUNT and SETTLECOUNT values, but the problem persisted. I then configured different IDRIVE values for the channels, and with this adjustment, the time before the issue appears increased to around 30 minutes.

What could be the root cause of this behavior? Any guidance or support on this issue would be appreciated.

  • 0
    TI__Mastermind 45305 points

    Hello,

    Can you please provide your schematic and register configuration?  

    Are you setting the idrive such that your sensor signal is between 1.2Vpk and 1.8Vpk?  

  • 0
    Prodigy 50 points

    Hello Eddie,

    The oscilloscope image and circuit diagram are attached.

    Our registry settings are as follows:

    fdc2214->rCount = 0xFFFF;
    fdc2214->offset = 0x0000;
    fdc2214->settleCount = 0x0400;
    fdc2214->clockDevider.all = 0x1001;
    fdc2214->errorConfig.all = 0x0001;
    fdc2214->generalConfig.all = 0x1E01;
    fdc2214->muxConfig.all = 0x820D;
    fdc2214->driveCurrent.all = 0x5000;
    fdc2214->externalOscFreq = 0x2625A00;

    When the LC tank enters resonance, the peak is 1.2397VDC, and when the peak ends and it returns to normal oscillation, I see 400mV on the oscilloscope. During liquid measurement, the capacitive voltage increases, rising to 1.8V.

    I don't think the issue I'm experiencing is related to this because I didn't encounter this problem when I was working with a single channel.

    Mesut Can

  • 0 in reply to Eddie LaCost
    Prodigy 50 points

    Hello,

    Will you get back to me on this matter?

  • 0 in reply to Mesut Can Yaman
    TI__Expert 7875 points

    Hi Mesut,

    Our experts on this topic are currently out of office for the holidays.  They should be able to respond after they are back on January 5th.

    Regards,

    Mekre

  • 0 in reply to Mekre Mesganaw
    Prodigy 50 points

    Hello,

    Will you get back to me on this matter?

  • 0 in reply to Mesut Can Yaman
    TI__Mastermind 45305 points

    Hi Mesut,

    This is a strange problem.  Do you see the same issue if you use the other two channels(ch2 or ch3)?  

    Have you seen this issue on multiple boards?  Have you tried replacing the IC on the board that shows the problem?  Maybe the IC was damaged on that channel.  

  • 0 in reply to Eddie LaCost
    Prodigy 50 points

    Hi Eddie,

    CH2 and CH3 are not connected in the layout on our board, so we couldn't test it. We replaced the board and IC, but the problem persisted. The issue was resolved when different current values ​​were set. However, we couldn't determine the cause.

  • 0 in reply to Mesut Can Yaman
    TI__Mastermind 45305 points

    Mesut,

    Glad to hear the issue was resolved with different idrive values used.  Did you have to increase the current drive?  I havent seen this issue before of not issuing the data ready flag, but there are issues that can occur when the signal level is not high enough.  Typically, this is exhibited as a lower SNR.