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TPS5430: audiable buzzing noise from power supply unit built with TPS5430

sathiya narayanan L
Prodigy 180 points
Part Number: TPS5430

Hi,

Currently for a project I have choose TPS5430 and have designed a board with it. Please find my schematics as attached.

My design requirement is input voltage ( 10 to 30 ) V and output current of 2.4A, at output voltage 8V. The output is fed to a processor, so if the processor is loaded to its maximum, it draws a variable current from 2A to 2.4A, at that stage I can able to hear the buzzing noise from the power supply unit. I suspect that this buzzing noise ( humming noise ) is from the inductor. Can  you please suggest me a possible solution to overcome this noise effect. The input and output capacitors used were ceramic and the inductor part number is SRN1060-220M.

Thanks

  • 0
    TI__Mastermind 25590 points
    Sathiya,

    First make sure it's the inductor and not the output caps. Ceramic caps can also produce audible noise.

    If it is the inductor you can try using a fully-shielded inductor, try an inductor with larger pads for more solder connection, or ask your inductor vendor for their recommendation on low audible noise inductors.

    -Sam
  • 0 in reply to Samuel Jaffe
    Prodigy 180 points
    hi Sam,
    Thanks for your reply, is it advisable to replace the ceramic capacitors to Tantalum or Aluminium capacitor? Because I have replaced it with Tantalum, but the regulator fails to work properly, the output is not stable. As in the datasheet it says that tantalum and electrolytic cap will have high ESR value,it will be better to use ceramic.
    thanks
  • 0 in reply to sathiya narayanan L
    TI__Mastermind 25590 points
    Sathiya,

    Yes, ceramic will have lower ESR but if they are causing the issue then you will need an alternative. Try the tantalum or aluminum caps on the output again but remove the compensation (C54, C55, C59). This may help stability since the IC has compensation built-in for this case.

    We can also try to see if there is an issue we're not considering. Do you have excessive ripple on VOUT? If so, that may cause more audible noise and should be fixed before we change the power stage.

    -Sam
  • 0 in reply to Samuel Jaffe
    Prodigy 180 points

    Sam,

    Thanks for your feedback, it worked :-) . I have removed the compensation network and replaced ceramic capacitors with tantalum. Now the buzzing noise was reduced nearly 90%. I have only 10% of noise. 

    I have a concern is it advisable to use T491D106M050AT as input capacitor, because it has 800mohms of ESR. But I'm not sure whether it will cause any problems. With the online TI simulation tool, I found that it suggests capacitors below 25mohms to be used with this regulator. But for my design it costs pretty high. so will it be advisable to use 800mohm ESR capacitor in the input?

    -Sathiya