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TPS61091: TPS61090, TPS61091, TPS61092 reverse current?

Stan 59800
Intellectual 460 points
Part Number: TPS61091
Other Parts Discussed in Thread: TPS61230, TPS61230A

What will happen if on VOut Boost output is connected (accidentally) a source of 5VDC (not a consumer) – let say by mistake I connect this output to a USB power outlet while TPS6109* is in boost mode?

(ref fig 13 on page 9 of datasheet SLVS484C –JUNE 2003–REVISED DECEMBER 2014)

Thanks

  • 0
    TI__Mastermind 46905 points

    Hi Stan,

    there is no reverse current if the power save mode is enabled. the device should stop switching if the setting VOUT is lower than 5V.

  • 0 in reply to Jasper Li
    Intellectual 460 points

    Hi Jasper,

    Maybe I was no clear enough, so let me try to put the question other way:

    This is a worst-case scenario (foolproof) test:

    Assume I have TPS6109* which VOut going through a switch to an USB connector.

    In position 1 of the switch TPS6109* is enabled and boost and the USB connector acts as Output to power some external device.

    Position 2 of the switch is for charging a LiIon battery, TPS6109* is disabled and its VOut is disconnected from the USB port, which in this case works as Input of 5VDC from external source.

     

    Now the question is: If any user make mistake and while above mentioned switch is in pos1, connects an external power source while at the same time TPS6109* boosting out:

    -       What damages could happen with TPS6109* ?

    -       What damages could happen to any of the most common designs wall adapter or any kind of common 5VDC USB chargers and/or power adapters ?

    Thanks

  • 0 in reply to Stan 59800
    TI__Mastermind 46905 points

    Hi Stan,

    I didn't see risk to TPS6109x if the device is set to power save mode by PS pin.

    if the USB voltage is higher than TPS6109x seeting output, the device will stop switching. if the USB voltage is lower than the TPS6109x setting output, the TPS6109x will try to regulate the output.

    i'm not sure about the risk to the adapter. I'm not sure about the internal design of the adapter. you can apply an EVM for reference.

    What is input voltage of the TPS6109x? the TPS6109x is a quite old device. I would suggest other solution if possible.

  • 0 in reply to Jasper Li
    Intellectual 460 points

    Hi Jasper,

    What newer alternative do you have in mind - can you give me some part numbers and I'll research them in specs and price if will fit better?

    Thanks

    BTW - if PS pin is not set - what are the risks?

  • 0 in reply to Stan 59800
    TI__Mastermind 46905 points

    Hi Stan,

    you can  have a look at TPS61230, TPS61230A 

    there would be reverse current back to boost input if the PS pin not set.