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TPA3140D2PWPEVM: has high frequecy noise when open the SS function

user4656546
Intellectual 475 points
Part Number: TPA3140D2PWPEVM
Other Parts Discussed in Thread: TPA3140D2

When I turn on the Spread Spectrum function of the EVM, it will generate some high frequency noise as show in the attached picture. How can I get rib of it? since we need the Spread spectrum mode to pass EMC of Line Conduct.

SS Off 1 mode:

    It is noise free, at least it is not hearable, the 750Khz and harmonic may be just equipment pick up.

SS Off 2 mode:

    It is also ok. very similar to SS Off 1 mode.

SS On 1 mode:

    The 9.66Khz tone is pretty annoying.

SS On 2 mode:

    The 4.7Khz tone and 9.4Khz tone is very annoying.

 

  • 0
    TI__Mastermind 24835 points
    Hello,
    I think the 10kHz noise can be removed if the application design is good enough. Could you please show me your SCH&PCB? Are you using differential or single-ended input mode? Please use the differential input mode as much as possible. And, the GNDing on the PCB is also very important for the noise mitigation, please also check the GNDing performance on your board. Analog ground and power ground should be connected at the thermal pad, which should be used as a central ground connection or star ground for the TPA3140D2. Please keep the current loop from each of the outputs through the the output filter and back to GND as small and tight as possible. The thermal pad must be soldered to the PCB for proper thermal performance and optimal reliability. Seven rows of solid vias should be equally spaced underneath the thermal land. The vias should connect to a solid copper plane, either on an internal layer or on the bottom layer of the PCB. Please also refer to our TPA3140D2 EVM design. www.ti.com/.../slou405.pdf
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    Intellectual 475 points
    Customer tested our EVM and complained about the high frequency noise.
  • 0 in reply to user4656546
    TI__Mastermind 24835 points

    Please also check the GNDing in your measurement setup(the GND connection between board and instrument).This measurement is sensitive.

    10kHz and 5kHz frequency exits and they are actually from the SS modulation. The following pictures show the frequency modulation when SS1 or SS2 enabled. But these tone noise can be suppressed obviously if take care of GNDing carefully in the design and measurement. This device is RTM for several years and it's widely used in TV/speaker market. We never heard customer's complaint on this issue.   

     

  • 0 in reply to Shawn Zheng
    TI__Expert 6985 points
    Hello! Did this help with your question? Thanks, Jeff