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TPS65070 switching power source

Thomas Wappler
Intellectual 395 points
Other Parts Discussed in Thread: TPS65070

Hi,

I have a application with both USB and AC supply. One of both supplys may be disconnected while the system has to stay powered.

Is there any automatic switching mechanism in the TPS65070?

Or must the application switch between AC and US (witch will result in the need for a fast respone)? I think to enable both AC and USB is not possible because I have to ensure that my AC Power source will not power into USB.

Thanks,

Thomas.

 

  • 0
    TI__Expert 7240 points

    Hey Thomas,

    There is an automatic switching mechanism in the TPS65070.  The datasheet provides specs on page 11 called Power Path Timing that specify how quickly the chip can switch between USB and AC power.

    As for enabling both AC and USB, a priority will be set in the software that will apply if both inputs are connected.

    Thanks,

    Ben

  • 0 in reply to Ben Hopf
    Intellectual 395 points

    Hi Ben,

    okay, I see. This feature is a bit hidden in the datasheet. :)

    Just to ensure that I understand you correct: When USB and AC is powered the "#USB power enable" and "#AC power enable" bits in PPATH1 Register determine what source is used?

    Now let's say USB is used (#USB power enabled = 0; #AC power enabled = 1). Then the TPS65070 will automatic set #AC power enabled = 0 (and #USB power enabled = 1 ?!) when USB power is removed?

    Thanks,

    Thomas.

  • 0 in reply to Thomas Wappler
    TI__Expert 7240 points

    Yes you are correct.  Those enable bits determine what source is used if they are both present. 

    Also, the TPS65070 WILL automatically set the AC enable bit to 0 and the USB enable bit to 1 if the USB power is removed from the circuit.

    Thanks,

    Ben