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TPS65261: AC spec on high side / low side MOSFET

Ann_Lien
Genius 11410 points
Part Number: TPS65261

Hello expert,

Customer measured VDs waveform and found out the Max/Min is out of datasheet spec. Do you have any method to reduce this ringing? We change Rboot to 2.2ohm but it is still not working. We don't have space to place snubber.

For maximum, customer has a de-rating spec which is 80% ABS max. So based on datasheet, maximum H/S VDS should be 16V. Below waveform is over this spec. 

For minimum, L/S VDS is -4.16 which is also way behind the spec. Please kindly provide the solution for us, thanks a lot for your help :)

Best regards,

Ann Lien

Best regards,

Ann Lien

  • 0
    TI__Genius 17390 points

    Hi Lien,

    Thanks for reaching out. Please kindly try below:

    (1) Could you please double confirm about their switch node test point and measurement method? To properly measure the voltage at the SW node, it is important to use the right measurement techniques. To achieve the most-accurate, noise-free measurement, it is recommended to measure SW waveform with minimum loop method and with full-bandwidth. Simply remove the hat from the probe tip and wrap a wire around the probe barrel for the ground connection. This minimizes the inductance by reducing the length of the ground return loop.

    (2) Please try with 10Ω Rbst to see any improvement.

    (3) Add snubber circuit and improve layout.

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    TI__Genius 11410 points

    Hello Lucia,

    We're already used the shortest trace of this case. We will check with 10ohm for Rboot and see if it is improved. Thanks!

    Best regards,

    Ann Lien

  • 0 in reply to Ann_Lien
    TI__Genius 17390 points

    Hi Lien,

    Do you use the method as shown above? And could customer improve the layout?

    Thanks!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    TI__Genius 11410 points

    Hello Lucia,

    I can double check with RD but as experience, they will use the shortest loop to measure it. Thanks!

    Best regards,

    Ann Lien

  • 0 in reply to Ann_Lien
    TI__Genius 17390 points

    Hi Lien,

    Thanks! It would be great if we can check the measurement method since it's important to get most accurate result.

    BRs

    Lucia