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Input Power Calculations

MR_DDM
Prodigy 60 points

I have a design where I need to generate several voltages to support.

Attached is a block diagram of the power management and looking for the power calculation for each input device for each device.

Easy calculation is Power input power out and power out is simply VI input = VI output.

Is there a TI tool that does this for you where you just change the devices.

ThanksPower Archecture.pdf

  • 0
    TI__Intellectual 1710 points

    Hi Mr DDM,

    There is no direct tool to estimate input power directly as of now. However I've attached below a image on how you can calculate approximate input power.

    firstly you need to calculate out power of all stages. once it is done, to calculate input power of final stage, you need to divide output power by the approximate efficiency of that stage (this data can be taken from datasheets). Then add up all input powers of last stages to get out put power of previous stage. and repeat. this flow is from right to left in the image attached below. I hope this will suffice for input power estimation.

    Also,

    In your block diagrams I noticed 2 converters connected in parallel in some places. I don't think we can short the outputs of 2 circuits unless they're identical. even then we have to make sure they're synchronized and don't pump current into each other in reverse direction.

    Regards,

    Vishwanath

  • 0 in reply to Vishwanath Tigadi
    Prodigy 60 points

    Couple comments:

    1) Where do you get the 90% efficiency for LDO devices?

    2) This brings up another issue about thermal

    Thanks

  • 0 in reply to MR_DDM
    TI__Intellectual 1710 points

    Hi Mr DDM,

    90% was an assumption to demonstrate calculations. I don't think that high efficiency is possible with LDO; kindly consider using Switch mode power converters if efficiency is of high importance in your design. 

    If you have concerns about thermal performance of any part/device in particular, kindly let us know and I'll loop in the respective applications team to help with the same.

    Regards,
    Vishwanath