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TPS65023RSB power dissipation

Hung Truong
Prodigy 80 points
Other Parts Discussed in Thread: TPS65023

Dear TI Engineers,

I have customers requesting TPS65023RSB power dissipation value.

Please provide documentation.

Thank you
Hung Truong

  • 0
    TI__Genius 16870 points

    Hi Hung,

    The thermal dissipation table is included in the datasheet on page 2.


    If you are looking for dissipated power in the device then please use the efficiency curves for the DCDCs on page 14 & 15. Back calculate the Ploss by using the Ploss = Pin - Pout where: Pout = Vout x Iout and Pin = Vin x Iin.
    Iin = (Vout x Iout) / (Vin x n) where: n is the expected efficiency at that Vin, Vout, & Iout conditions.

    LDO Ploss can be calculated simply by Ploss = Iout x (Vin - Vout)

  • 0 in reply to Michael Green
    Prodigy 80 points
    Hi Michael,

    Can you show an example of calculation for dissipated power in the device.
    I am now sure how you determine the n value.

    What is the difference in dissipation power in device and LDO Ploss?

    thank you
    Hung
  • 0 in reply to Hung Truong
    TI__Genius 16870 points

    Read efficiency off the graph for an estimation. Example: using figure 1 in the datasheet:

    For:

    • Vout = 1.2
    • Vin = 3.6V
    • Iout = 10mA
    • n = 85%

    Iin = Vout * Iout / Vin / n = 1.2V * 10mA / 3.6V / 0.85 = 3.9mA

    Ploss = Pin - Pout = Vin * Iin - Vout * Iout = 3.6V * 3.9mA - 1.2V * 10mA = 2.04mW

  • 0 in reply to Michael Green
    Prodigy 80 points
    Michael,

    thank you for the info.

    I see that there are six graphs, why did you choice graph #1?

    These graphs are title DCDC1,DCDC2,and DCDC3, this calculation is power dissipation at the pins?

    I am looking to calculate the IC total power dissipation at 25C and 85C, Is this information available?
    How do you calculate it?


    thank you
    Hung Truong
  • 0 in reply to Hung Truong
    TI__Genius 16870 points

    Hung, 

    Are you trying to find the dissipation inside the IC package for a thermal analysis or the Ploss of the entire converter including inductor and such?

    If you are looking for the entire converter then you can use the method that I described above but, if you are looking for the power loss inside the IC package then that is a bit trickier. You will need to calculate the conduction and switching, (including gate drive and body diode), losses. This app note show a walk through of the calculation that you might be interested in conducting: http://www.ti.com/lit/an/slpa009a/slpa009a.pdf?keyMatch=power%20loss%20buck&tisearch=Search-EN-TechDocs

    Since, we don't offer some of the information on the DCDCs of the TPS65023 needed for the calculations described in the app note, I would suggest generalizing and estimating when possible to reduce the calculation head ache. Since, the only major Ploss device outside of the IC is the inductor try using the efficiency curves to estimate total Ploss of the converter and then subtract the inductor ACR, core and DCR losses from the total to get an estimated IC power loss.

    See app note from Coilcraft: http://www.coilcraft.com/pdfs/doc486_InductorLosses.pdf

    and inductor calculator that combines ACR and core losses: http://www.coilcraft.com/apps/loss/loss_1.cfm?family=xfl3010