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TPS65218: Strange rising wave on DCDC4

Mitsuharu Iwasaki55
Intellectual 750 points
Part Number: TPS65218

Hello all,

I saw strange rising wave like a triangle on DCDC4. It's attachied.

What is this phenomenon? Please tell me mechanismof the generation.

Is this something error?  This wave is measured by TI TPs65218 EVM.

Regards.,

Mitsuharu Iwasaki

  • 0
    TI__Genius 9380 points
    Mitsuharu,
    You did not provide much information on this signal, but to me it looks like the rising edge of the DCDC output voltage. If I am wrong please explain where the waveform is coming from.
    If it is the output voltage of the DCDC during startup then the rise is normal. The voltage on the output capacitor starts at zero. The DCDC controller sets a duty cycle controlled output during startup to control and limit the current during the startup period. This provide current limiting and soft start control to the output to prevent overshoot in the output.
    I hope this answers your question. If I misunderstood your question please clarify.
    Thank you
  • 0 in reply to Gordon Varney
    Intellectual 750 points

    Hello Gordon,

    Thank your for replying. I attached additional information.

    I'm asking it because our customer has issue. They made 88 EVBs. But 22 EVBs don't work.

    DCDC4 don't start up. Please give me your cooment for ataached file.

    Regards.,

    Mitsuharu Iwasaki

    TPS65218DCDC4.pdf

  • 0 in reply to Mitsuharu Iwasaki55
    TI__Intellectual 1990 points

    Iwasaki-san,

    Would you be able to share the customer's schematic and layout for this system? I would like to see how the DCDC4 is used in their system. You can send them to my email at p-kundmueller@ti.com. Let me know if there are any questions. Thanks!

    Regards,

    Paul Kundmueller