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LP5907: LP5907SNX_3.3V output oscillation(~360KHz), please help, which cause the Oscillation, why highi input lead to higher ripple

sir liu
Prodigy 60 points
Part Number: LP5907

Gentlemen

     we use the several pcs LP5907SNX_3.3V at our module, while find the LP5907SNX_3.3V output got oscillation, the frequency is about 360KHz. the output cap PN CL03A105MP3NSNC from samsung, voltage rate 10V.

  3.8V_SW is the input power, inital set the 3.8V_SW = 3.5V, the ourput ripple is ~20mV

when  set the 3.8V_SW = 3.8V, the ourput ripple is 80mV high

when  set the 3.8V_SW = 4.0V, the ourput ripple is 100mV high

 what caused the oscilllation and which the higher input power could cause the high osicalltion, any clue

Apprieciate the support and help.

      the Sch

Input power =3.6V, output ripple 20mV

Input power =3.6V, output ripple 70mV

Input power =3.8V, output ripple 70mV

Input power =4.0V, output ripple 80mV

  • 0
    TI__Genius 13285 points
    Hello,
    This looks like an identical post. I'll continue to respond on the other post and consider this post closed.
    Regards,
    Mike
  • 0 in reply to Michael Hartshorne
    Prodigy 60 points

    Hi, Mike

       Thanks for the reponse.

       the post is same as the before one which can not show the waveform,

    I just repost the sch and waveform, while looks waveform not show as well.

    the queston is why the oscillation at output is right round 360KHz?

    and why the higher input lead to higher ripple ( when 3.6V input, output have 20mV ripple, and when 3.8V input, the output have 70~80mV ripple, when 4V input the output have 80~100mV ripple)

    THanks again for the support.

    Liu