• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 63 subscribers
  • Views 855 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Power Dissipation Equation - LMZ36002

Ryan Williams
Prodigy 60 points
Other Parts Discussed in Thread: LMZ36002

What is the equation used to determine the power dissipation of the LMZ36002?

  • 0
    TI__Mastermind 28020 points

    The power dissipation can be calculated as: (Vin x Iin) - (Vout x Iout)

    You can also check the Typical Characteristics section of the datasheet and view teh power dissipation graph.

  • 0 in reply to J Arrigo
    Prodigy 60 points

    With input voltage, output voltage, output current, and switching frequency... how would you determine Iin or Power Dissipation?  The above equation assumes you know the total part's power dissipation or input current, which would be a factory of losses and switching frequency.

  • 0 in reply to Ryan Williams
    TI__Mastermind 28020 points

    The power dissipation curves in the datasheet are only for the recommended switching frequency. Operating at another switching frequency will effect the power dissipation. An EVM can be used to measure power dissipation for other operating conditions.

  • 0 in reply to Ryan Williams
    TI__Mastermind 28020 points
    Additionally, you can use TI's Webench tool to enter your operating conditions and it will calculate the efficiency. If you know your output power and the efficiency, the power dissipation can be easily calculated.
  • 0 in reply to J Arrigo
    Prodigy 60 points

    Thank you for the response... I appreciate the options to use the datasheet, simulate on Webrench, and/or use a development module... but I'm looking for a way to calculate these items given the known inputs.  Typically TI includes a Power Dissipation equation within their datasheet to Calculate the theoretical value.  I view this as an analytical means to calculate power dissipation instead of an empirical or simulation mechanism... that's ultimately what I'm looking for in this situation is the analytical means for calculating power dissipation when knowing the variables of input voltage, output voltage, output load, and frequency.

    Thanks,

    Ryan

  • 0 in reply to Ryan Williams
    TI__Genius 15810 points
    The calculations in Webench are not empirical. They include all the right equations for the conduction, switching and other house keeping losses occurring in the IC. Conduction losses are caused due to the voltage drop across the internal MOSFETs due to a finite value of the channel's on resistance. The switching losses are caused during the time when the MOSFET is changing state from off to on. There are also gate drive losses which are directly proportional to the switching frequency of the design. Webench uses the device specific parametric data for the above mentioned calculations which makes the results authentic. Unfortunately some of this data is also not share-able.

    In case you are looking at ways to calculate efficiency, you could follow this blog series: e2e.ti.com/.../dc-dc-converter-datasheets-system-efficiency-demystified

    I hope this helps.