• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 65 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TPS51120: The output wavefrom normal

Zhang Liang
Expert 2435 points
Part Number: TPS51120

Tool/software:

Hi,

We use the TPS51120 for the 5V/3.3V buck design, and now, we find the 5V output inductive howling when we set the light-load( the switching frequency is only less then 5KHz),

and we add the load that the Inductive howling is removed;

Now we set the fixed PWM mode, there are no inductive howling but the Inductive heating so severe, we change the inductive to 1uH but the heating is more severe;

Please review below schematic diagram and waveform and advise why we use the inductive is heating? thanks.

  • 0
    TI__Mastermind 46930 points

    Hi Liang,

    This behavior looks normal. If sets to Auto-skip mode, the switching frequency will be lower at light load to maintain high efficiency. If sets to forced PWM mode, the switching frequency will keep at the frequency selected by TONSEL input and the efficiency will be lower at light load. At heavy load, both modes should have same efficiency. Please refer to section 7.3.3 in the datasheet.

    Hope this helps,

    Thanks,

    Nancy