CN0350 DAQ calibration

I have got CN3050 EValuation kit and tried to calibrate using function generator with 1KHZ sine wave of amplitude 1V as per the reference document.The output of FG is connected to CAL and NEG signals of J1 connector.After calibration for 1000pC,I tried to acquire the signals with same Function Generator and the following observations were made:

There is ripple overriding the sine wave and also the frequency of acquired signal is 50Hz which is equal to line frequency and the ripple frequency is 1Khz.

If I change the amplitude of sine wave also there is no change in MIN and MAX coulomb values.

Could you please provide your inputs to resolve this

  • 0
    •  Analog Employees 
    on Sep 28, 2020 5:55 PM 2 months ago

    Hi shankar,

    Have you done any edits to the board, like for example changing Ccal? I am unable to replicate your issue with the CN0350 board that I have.

    With regards to the 50Hz signal that you are seeing, this may be due to the dc supply connected to the SDP-I-PMOD interposer board.

    Regards.

  • Hi,

    I have not changed any values on board.

    I am using EVAL-CFTL-6V-PWRZ power supply for powering the following boards:

    • EVAL-CN0350-PMDZ circuit evaluation board
    • EVAL-SDP-CB1Z SDP evaluation board
    • SDP-PMD-IB1Z interposer board

    Could you please let me know the Function Generator settings(output impedance settings) and connections made with your setup for calibration.I am using Agilent 33220A function generator to generate 1Khz sine wave with amplitude 1V.

    Please share any video for calibration setup.

  • 0
    •  Analog Employees 
    on Sep 30, 2020 7:11 AM 2 months ago in reply to shankar_25

    Hi shankar,

    Here is the setup in my desk:

    I am also using an Agilent 33220A, 50ohms impedance at 1kHz frequency. What connector for the function generator are you using? This can affect the input signal to the CN0350.

    Regards.

  • Hi,

    Thanks for your inputs.

    I have changed the connector and got re-calibrated again.

    Currently with 50 ohms load impedance and 2Vp-p amplitude and 0V offset settings,now readings are better.

    But the waveform got clamped for 1Vp sine wave input at 1KHZ and readings shows closer values +/-1000pc.

    When I changed to Vp-p to 1.3V the waveform looks like perfect sine wave.