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Noise measures of UCC28070

Kei Sato73562
Expert 2310 points
Other Parts Discussed in Thread: UCC28070

Hello

I have a question of UCC28070.

Please tell me about a noise measures method of the input electric current.

Please confirm an attached file about the details.

Best Regards,

Kei

Noise measures of UCC28070QPWRQ1.pptx
  • 0
    TI__Mastermind 26500 points

    The inductor current is higher at lower input voltage and higher load current. Please measure the inductor current and check if there is inductor saturation during these conditions.

  • 0 in reply to Mahmoud Harmouch
    Expert 2310 points

    Hello Harmouch,

    Thank you for your reply.

    The inductor is not a saturated type.

    Therefore there cannot be the thing that an inductance level suddenly falls at the time of high electric current.

    - Inductor Current

       RMS Current : 8Arms

       Peak Current : 16A

       Current of the noise : 11A

    - Specifications of the inductor

       RMS Current : 8Arms → 145uH

       Peak Current : 16A → 85uH

       Current of the noise : 11A →115uH

    Would you tell me some causes that a noise happens?

    Would you tell me some methods to reduce a noise?

    I do not mind even a method thought about.

    I'm sorry. I want an answer by 27th.

  • 0 in reply to Kei Sato73562
    TI__Mastermind 26500 points

    Sorry we had long weekend in US and was not able to answer by 27th. It is a current spikes and not noise. I can see it happens during zero crossing of the of the AC voltage. At zero crossing the rectified voltage is at its lowest value. The current demand is high. Make sure the input capacitor can deliver the current and has low impedance. You can try adding more ceramic capacitor.

    I would like to see the following waveform:

    1- rectified input voltage VIN

    2- Inductor current

  • 0 in reply to Mahmoud Harmouch
    Expert 2310 points

    Hello Mahmoud,

    Thank you for your support.

    It is said that I cannot submit them from the OEM maker.

    I inform it of an assumed cause by the following contents.

    - It is thought that lack of adjustment of Rsyn.

    - It is thought that adjustment frequency of CAOA and CAOB is too low.

    - It is thought that RC filter of CSA and CSB is too big.

    Best Regards,

    Kei