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LM2677: Trying to determine the LM2677's suitability for use in a rocket

Evan Clark
Prodigy 20 points
Part Number: LM2677

I'm helping to design the power system for a rocket and I need to know the mechanical characteristics of the LM2677, like how much stress or shock it can take, etc... I am also trying to find out its response time to changes in the input voltage. I looked on the datasheet and found some graphs in section 6.10 that I think deal with this, but, for the most part, I didn't see anything telling me which pin goes with which graph.

  • 0
    TI__Genius 11040 points
    Hi Evan,

    The mechanical characteristics is not public information. I can work to share this information with you over e-mail. Could you share your e-mail with me?

    Regarding your second question, LM2677 is a voltage mode control device. Consequently, as long as the loop response is stable, the output voltage will remain in regulation and respond to the input voltage.

    Best Regards,
    Katelyn
  • 0 in reply to Katelyn Wiggenhorn
    Prodigy 20 points
    Hi Katelyn,

    Thank you for responding! So, to clarify, if the input voltage suddenly dropped from 30V to 20V, the output voltage wouldn't waiver at all? Even for just a few milliseconds? We're planning on using this to provide power for Raspberry Pi's for the rocket. I know Raspbeerry Pi's take power over USB, so it probably has some filters on the Pi, but we haven't found out specific tolerances yet.
    Also, my email is evanc42@vt.edu. Thank you for helping.

    Sincerely,
    Evan Clark
  • 0 in reply to Evan Clark
    TI__Genius 11040 points
    Hi Evan,

    Yes, the LM2677 is a voltage mode converter with feed-forward. Consequently, the device should have constant loop gain with changing input voltage and the output voltage will remain constant. If you are interested in reading more about voltage mode control, voltage mode control with feed forward, and current mode control, this article provides a good introduction: www.ti.com/.../slua119.pdf

    Regarding the mechanical stress, I have reached out to our packaging team, and I will get back to you with further information.

    Best Regards,
    Katelyn
  • 0 in reply to Katelyn Wiggenhorn
    TI__Expert 3840 points
    Hi Evan,

    We apologize for the delay, but we don't have any mechanical stress data available for this package.

    Best Regards,
    -JP