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PTH03050Y: High Humidity High Temperature Operation

Kazuki Itoh
Genius 10770 points
Part Number: PTH03050Y

Hello team,

My customer observes the output voltage oscillation right after the start up after leaving PTH03050Y in 45degC 95%RH environment.

Can you let us know if this is supported?

I don't get because humidity specification is not clearly stated in the datasheet.

Regards,

Itoh

  • 0
    TI__Guru**** 150830 points

    Hi Itoh-san,

    Can you post a waveform of Vin, Vout, Vref, and Inhibit that shows the issue?

    Does the issue occur with a normal/lower humidity?

    Does the high humidity level condense into water on the module?  This can cause shorts.

  • 0 in reply to Chris Glaser
    TI__Genius 10770 points

    Hello Chris-san,

    Please find waveforms and schematic from the internal link here.

    The customer still sees the oscillation after the coating to improve operation under humidity.

    The oscillation looks like sawtooth. Do you have any idea about the cause of this oscillation?

    The abnormal operation gets better when customer tried power cycle, so it should not be due to the water.

    Regards,

    Itoh 

  • 0 in reply to Kazuki Itoh
    TI__Guru**** 150830 points

    Thank you for sending these details Itoh-san.

    What is different between the good startup and the abnormal startup?  Do different devices work or not work?  How many different devices have they tested?  Does the same device sometimes work and sometimes not work, under the same conditions?  Does the abnormal startup only occur in the high humidity environment or does it occur under normal conditions?

    On their schematic, they violate the output capacitor guidelines in the D/S:
    When used on the output their combined ESR is not critical as long as the total value of ceramic capacitance does not exceed 300 µF. Also, to prevent the formation of local resonances, do not place more than five identical ceramic capacitors in parallel with values of 10 µF or greater

    Can they retest with a high-ESR (>8 mOhm) electrolytic/tantalum/polymer cap on the output, in addition to just 300uF of ceramic?