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Power supply OR-ing with reverse current protection

Benjamin Brammer
Intellectual 460 points
Other Parts Discussed in Thread: LP5900, LM74610-Q1, LM66100, TPS2115A, TPS2121, TPS2120

Hello,

for an upcoming project of a portable device that has the possibility to be connected to an USB 2.0 host system I want to implement a power supply OR-ing scheme where I actively switch from my primary battery supply (possibly alkaline primary battery) to the supplied 5V from the USB VBus if it is available to safe battery life time. I first thought of switching between the two supplies with my used microcontroller if VBus is sensed but after some research I found the SLVAE57 application report from TI and thought your ideal diode controllers might be a solution also integrating battery protection for reverse currents or wrong polarity battery insertion.
I searched in your product tree but I am not sure if this is the right solution for my project.

These are my powers supply requirements so far:

  • primary battery (2x alkaline or 1x Li-based)
  • TPS6300 for gnerating 3.4V supply for microcontroller
  • LP5900 for 3.3V clean analog supply
  • USB Vbus as secondary power supply when attached

As the TPS6300 can operate from 1.9V - 5.5V I would only need a suitable OR-ing scheme chip with integrated battery protection.
I would be happy if someone could give me some suggestions.

best regards

Benjamin

  • 0
    Intellectual 460 points

    I think maybe the LM74610-Q1 is a suitable solution..

  • 0 in reply to Benjamin Brammer
    TI__Mastermind 32650 points

    Hi Benjamin,

    Do you need OR-ing or priority PowerMUXing? The difference between the two is OR-ing always passes the highest voltage supply to the output while PowerMUXing allows for priority to be set for specific sources to be used.

    If OR-ing is required, I would suggest 2x LM66100 which are integrated "Idea Diode" devices that have low Iq and are meant for lower power applications.

    If PowerMUXing is required, I would suggest the TPS211xA devices like the TPS2115A which are low voltage power MUXes meant for lower power applications.

    We also have TPS2121 and TPS2120 which are higher power devices(and capable of fast switchover times) but these may be overspec'd for your system.

    Let me know if you have further questions on these device. Thank you for choosing TI Power Switches for your designs.

  • 0 in reply to Shreyas Dmello
    Intellectual 460 points

    Hello Shreyas Dmello,

    thanks for your answer. Since the battery voltage is always lower than the VBus voltage I could choose both possibilities. Under project cost aspects the LM66100 would be the best choice.

    The LM74610-Q1 would also fit, but would have more external components to supply, right?

    bestregards

    Benjamin

  • 0 in reply to Shreyas Dmello
    Prodigy 90 points

    Hi Shreyas

       what is the dead-time value for using mux to switch between two power sources?

    Thanks,

    Tony

  • 0 in reply to Tony Wang3
    TI__Mastermind 32650 points

    Hi Tony,

    By dead time I think you mean switchover time? This depends on the mode of operation that TPS2121 is in as well as the application itself.

    In the VCOMP mode. the switchover time is 100us while in XCOMP mode the switchover time is spec'd at 5us. Please look at the datasheet to see how TI defines switchover time (Figure 16).