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LM3489: Asking for LM3489 audible noise design review and suggestions

SHH
Mastermind 30966 points
Part Number: LM3489

Hi Team,

Customer would change the output cap to increase the output cap value to avoid the audible noise while charging NB.

C7202 change to 220uF

C7713 change to 100uF

 

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1177244/lm3489-asking-for-lm3489-audible-noise-review-and-suggestions?tisearch=e2e-quicksearch&keymatch=lm3489%20noise

 

 


Would you please help review  solution and provide your comments?

Thanks for help!

 

SHH

  • 0
    TI__Guru 50120 points

    Hi SHH,

    Schematic received. Please expect to hear back from me soon on the review of this device. 

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    TI__Guru 50120 points

    Hi,

    Most of the schematic components looks to be similar to the E2E post that Orlando replied to. 

    Are you still have audible noise issues with this application? 

    If so, please probe the SW node (left side of the inductor terminal) to see if there is any abnormal switching characteristic during loading.

    Regards,

    Jimmy 

  • 0 in reply to Jimmy Hua
    TI__Expert 3465 points

    Hi Jimmy,

    Customer has better result with those component change C7202, C7713. Are these change going to affect performance a lot?

    One more thing, customer is testing dynamic performance, if customer changes L7201 from 10uH into 2.2uH, is that ok?

  • 0 in reply to Oliver Lin
    TI__Guru 50120 points

    Hello,

    The output capacitance change is okay since customer is increasing it. This will help with stability and load transient.

    I would suggest customer stick with the 10uH since this USB type C application needs to regulate 5V to 20V. A 2.2uH may not be sufficient for proper regulation of higher output voltages.

    Regards,

    Jimmy