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PTH05000W: The drop-down and glitch

Part Number: PTH05000W

Hi Sir/Madam,

I have some modules with PTH05000Ws which transfer from

- DC5V to DC3.3V, 

-DC5V to DC2.5V, 

-DC5V to DC1.8V,

the current issue is that input DC5v has a drop-down every 1ms, the oscilloscope wave as follwed:

And DC3.3v module has a glitch, the situation is sporadic, sometimes 10mins, sometimes 20mins, the oscilloscope wave following:

My load is XC5VSX95T from xinlinx company, and it works normally until now. But I want to figure out the reason of the drop-down and glitch, please point me to it.

Thanks in advance.

Best Regards, 

  • Hi :

    Send the complete schematic along with input and output capacitors include capacitor type, capacitance value , aluminum or polymer , ceramic capacitors, for each module and ESR if possible. .

    Tom  

  • Hi Tom,

    Thank you for your quirk response.

    Actually the capacitors of input and output are tantalum capacitors, the value as illustrates, does it have essential relations?

    The complete schematic as following....

    7043.SCHEMATIC1 _ 5V3V3.pdf

  • Hi Jenny;

    I reviewed the schematic.. One question, What is the ESR of the output polarized capacitors? Can you sent me this specification?

    The vendor typically publishes ESR? 

    1.Based upon the data , I did not see how the PTH power modules can generate this 12.5KHz *** on the input 5V.

    2. If the input 5V droops due to high loads on Vout  DC power supplies  to  below about 4.2V,then it can  force the  Vin  5V PTH power modules to start to restart and power on cycle.. 3. Can you send pictures of PTH Vout  when this occur, each 1V8, 3V3, 2V5  and 0V9 ?

    Tom

    Can you send me the details

  • Hi Tom,
    I am sorry to reply so late. The specification of output capacitors as attached. Please help to  figure out this issue. 

    ESR.xls

  • Hi Jenny:

    Thanks for the capacitors information. The ESR 's on these  capacitors are fine for the PTH05000.

    .Based upon the data , I did not see how the PTH power modules can generate this 12.5KHz *** on the input 5V.

    2. If the input 5V droops due to high loads on Vout  DC power supplies  to  below about 4.2V,then it can  force the  Vin  5V PTH power modules to start to restart and power on cycle.. 3. Can you send pictures of PTH Vout  when this occur, each 1V8, 3V3, 2V5  and 0V9 ?

    Tom

  • Jenny:

    I also recommend open R1050,R1089,R1091 from 5V ,PTH05000 input pin  controlled voltage .. Each PTH05000 has its own internal pull-up and time control. When you apply 5V  Inhibit pin 3.which defeats  soft start function. This externally applied 5v  defeats the pre-bias control function.  

    In your application, If inhibit is required  in this application, it most be controlled with a open drain FET. There should be no external voltage applied to the inhibit at any time.

    Tom