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tps54325

Danny Kwon
Intellectual 1900 points
Other Parts Discussed in Thread: TPS54325

 

In case of Vin=12V, Vout=5V,  Iout=1A, (using P5103EMG mosfet) 

If customer add 470uF electrolytic capacitor with 12V power supply and repeat power on-> Off -> On,

then the output voltage didn't come out.

If customer remove 470uF electrolitic capcaitor then this problem disappear.

Attached final schematic , Pls check there is no critical problem in the TPS54325 part.

And let us know if it is impossible to use electrolytic capacitor ?

 

 

Sub-14R-10A.pdf
  • 0
    TI__Guru**** 191445 points

    What is the reference designator of the AL 470 uF capacitor?  Is it applied to the input or the output of the TPS54325?  The TPS54325 is meant for use with ceramic or low ESR output capacitors.  If it is on teh input supply, I have tested teh TPS54325 many times with large electrolytic input caps (keeping the ceramic input caps close to the TPS54325 device).  I have never seen any problem with power up.  It looks like you get input from a wall wart.  It is possible that the wall wart is the issue.  Can you provide start up waveforms for analysis?

  • 0 in reply to JohnTucker
    TI__Intellectual 1900 points

    Hi John,

    It is applied to the input (+12v). In your message, you have tested with many times with large electrolytic input caps(not ceramic) and there was no problem right?

    I recommended ceramic caps but customer just used electrolytic caps by themselves.

    I will update the start up waveforms after getting it from customr soon.

  • 0 in reply to Danny Kwon
    TI__Guru**** 191445 points

    The al electro;ytic cap on teh input is in addition to the standard ceramic bypass capacitors.  I have never tested with only aluminum electrolytic.  I would not be surprised if there were a problem.  Most dc/dc converters are very sensitive to the input cpacitor.  They require a high quality ceramic very close to the IC.  I cannot guarantee operation without the required ceramic bypass.  I still would like to see the waveforms.