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TPS62125: Parallel connection: an external DC/DC and TPS62125

Eduardo Mateos
Prodigy 30 points
Part Number: TPS62125

I am considering to use TPS62125 in a harvest energy design. For debugging  propose I would like to connect in parallel an external DC/DC, because it is much more comfortable. My intention is to  assembly a small connector at the TPS62125 output, plug in an external  DC/DC and use this power unit for debugging. I want to use  the typical application which you can see on the datasheet. I wonder if TPS62125 can be damaged when I connect other DC/DC in parallel at the output but without input power. In other words what happens when I connect 3v3 on pins SW and VOS without any voltage on VIN?

NOTE: I would like to avoid a mechanical switch because the extra cost, and also because reliability (it has to be working during more than 15 years). Also two diodes is not a solution because the efficiency. 

  • 0
    TI__Guru*** 142860 points
    This app note, found on the product page, should answer your question: www.ti.com/.../slyt689.pdf

    What are you using for the main harvester and DC/DC?
  • 0 in reply to Chris Glaser
    Prodigy 30 points

    Thanks Chris. The App note is quite good. Unfortunately  I can´t use any diode because power efficiency would drop

    I use as a main Harvester a solar cell. I think it is ok because this solar cell  behaves like diode and in my case if voltage is lower than 6v should be not a big issue.

    I need around 500mW at 3v3, this is the reason I chose TPS62125, because the highest efficiency at this current (100-200 mA) 

    For the external DC/DC most probably we will use a power supply from the lab at least for debugging proposal and on the field it is not defined yet.

    Regards

    Eduardo