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TPSF12C1QEVM: No change on the noise

David Huang
Intellectual 2285 points
Part Number: TPSF12C1QEVM

Hi team,

My customer is evaluating the device in their robotics application.

After testing with the following setup, they reported that the noise did not get any better and the filter was not working.

Is there anything they could do to make the device work better?

Regards,

  • 0
    TI__Guru 59957 points

    Hi David,

    Please send a completed quickstart file for review - here is the latest version:

     1778.TPSF12Cx quickstart calculator Rev A4.xlsm

    Here is the design process:

    1. Complete the quickstart file using impedance data or model parameters for the required CM chokes. Derive damping component values for stability.
    2. Verify the design in SIMPLIS or PSPICE. Verify that the INJ voltage is within its operating window (2.5V to VDD - 2V).
    3. Perform low-voltage testing on the design (insertion loss test, CM excitation using a function generator with square wave injected through a 1nF cap, check stability). Note the INJ voltage should be Vdd/2 when VDD is applied and no CM signal excitation - if the INJ voltage has AC content then, it indicates instability.
    4. Perform high-voltage testing when attached to the regulator. Again , ensure the INJ voltage is not getting railed or clipped. Note that DM noise is also present, so check the CM performance by using a splitter to look at the CM noise separately.

    Note in your schematic above there should not be any Y cap loading the AEF. Also, 680pF is the default sense cap, but 1nF is also acceptable (giving slightly less rejection of 50Hz).

    It would be great if you can also send a photo of your setup.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    TI__Guru 59957 points

    By the way, we just released a complete filter board EVM with AEF - see here www.ti.com/tool/tpsf12c1evm-filter. The user's guide also has additional information for test setup, etc.