This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CC3235S: failed FCC Testing, complete part no.: CC3235SM2RGKR

Part Number: CC3235S

Number: CS1006965
Contact: Hans Peter Jilg
First name: Hans Peter
Last name: Jilg
Short description: failed FCC Testing
Email: hans-peter.jilg@renfert.de
Company: Renfert GmbH
Company phone:
Language: German
State: Open
Provide case details or comments:

 To whom it may concern,

we have an appliance using the above mentioned SimpleLink WiFi Chip.

The testing for FCC compliance at the CSA Testlab failed, because the RMS value ist above the limit of 54 dBµV/m.  

The test is done using the TI Radio test tool with the settings you see here:

The result of the measurement you see here:

The black line is the RMS value and the limit is exceeded at point M7 and M8.

The design is not so sophisticated, the WiFi chip and a filter band pass, finished:

 

Can you provide any information what might cause this problem.

For additional information: We did also the testing for the RED (for Europe) at the VDE testlab and hab not problem there.

This is the measurement plot from VDE:

The green line is the RMS value.

Surprising, the line is much lower in this plot, and also we do not see the humps right and left of the 2.4 GHz.

Do you have any idea. If you need more information, please let me know

All pictures you also find attached. Thank you very much.

Seiten aus VDE_Test-Report_EMC_274863_TL7_2_2021-06-24_.pdf  REN01.0120-ES-0011.pdfREN01.0120-LY-0011.pdfREN01.0120-LY-0011-3D.pdf

Another questions:

- Why does the part number selection filed does not recognize the complete part number?

- Why is it not possible to select a different forum before posting the request? 

Best regards

 

Hans Peter Jilg

Technische Dokumentation

Technical Documentation

 

Renfert GmbH

Untere Gießwiesen 2

78247 Hilzingen / Germany

 

Tel: +49 7731 8208-29

Fax +49 7731 8208-70

hans-peter.jilg@renfert.com

www.renfert.com

  • Hi Hans,

    I am unable to gather much information from REN01.0120-LY-0011.pdf and REN01.0120-LY-0011-3D.pdf.

    Please request an official design review from here and make sure you include the schematic and the gerbers (or Altium files) so that I could review your design. 

    BR,

    Seong

  • Hi Seong Kim

    thank you for your reply.

    I think we are not yet at the point, reviewing the design.

    I think we have more of a "test setup problem" then a design problem, because we passed all necessary test for the RED (Europe directive).

    The CSA lab is doing the tests using die TI Radio Tool. And we have the problem with the measurement of "FCC Part 15 C (intentional Radiator) §247" with the average value, black line in this diagram:

    The curious thing is, that two lines (blue and black) are more or less identically, only differs by an offset, while one is showing peak values, the other is showing the average value of the spurious radiation. I would expect a bigger difference.

    May be you have someone available with deeper knowledge of the FCC testing, how can give me some information, how to set up or how to operate the TI Radio Tool for this spurious radiation testing. Thank you

    Regards Hans Peter Jilg

  • Hi Hans,

    The key for spurious emissions is following our reference design. You need to keep decoupling caps close to the pins, you need to isolate the ground for the DC/DC, and you need proper 50 impedance for your RF path. If any of these aren’t followed there could be issues.

    Also, ensure you are using the latest Radio Tool v1.0.3.19. And using the latest service pack.

    In Radio Tool, configure the EUT to the desired parameters such as Channel/Frequency, Data Rate, Data Pattern, Power Level, and so forth. 

    You can also try using Packetized TX mode and tuning the size and delay parameters to transmit at a 30% duty cycle. This can be measured using a spectrum analyzer's zero span setting. By doing this, the PA does not overheat, and the RF power does not degrade over time. 

    BR,

    Seong

  • Hans,

    I also see from your schematic that the antenna matching components are identical to our LaunchPad reference design. 2.2 and 3.9. 

    Note that you most likely need to further tune the antenna as your custom board stackup is not identical to our LAUNCHXL-CC3235S.

    BR,

    Seong