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TPS60123: Using output control En pin through Diode

Anh Hoang
Prodigy 50 points
Part Number: TPS60123
Other Parts Discussed in Thread: BQ25173, TPS61023

Hi everyone.

I'm building Power Multiplexing Using Load Switches using Boost converter.

My purpose: That's will switch Power supply between 5V_ISO(5VDC) and VOUT_BQ25173(4VDC) if any one of both power supply have problem.

Because VEN_H (Pin 2 of TPS61203) = 1.2V, so if my Battery lower 1.2V the output will OFF. I want to use maximize power off battery to supply to the Load when main power is loss, so I connected the Output of TPS61023 to EN pin through diode (Vf =200mA), it will run until battery < 0.5V.

Can you check my schematic and give me some advices for:

 - This design for TPS61023 is correct, and it can run normally?

 - Do you have another solution for my idea?

 - If my design is correct, can you give me some diode have lowest Vf?

Thanks for your support

  • 0
    TI__Mastermind 32350 points

    Hi  Anh,

    please add more output cap with your TPS61023, cap after diode should not be considered as output cap totoally.

    actually, i am not sure about the other part. but i'd like to reminder that there always some delay time of buffer and delay of EN pulled high to switching of TPS61023. so may be the output may crahsed during transition from 5V_ISO to 4V_battery.

    so i think it is better you can force the EN of TPS61023 high, and remove the buffer. if 5V_ISO on, TPS61023 will run in PFM mode and i think the consumption should smaller than 40uA. how do you think about this?

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Prodigy 50 points

    Hi Tao.

    Thanks for your respond.

    I will add more cap at the output of TPS61023.

    My schematic I designed basic on Automatic Switchover MUX form TI (https://www.ti.com/lit/an/slva811a/slva811a.pdf) page 7/18, so I don't think the output may be crashed during transition from 5V_ISO to 4V_Battery.

    Beside that the output (Vout_TPS29540) is power supply for buck power to 3.3V, so it can down to 3.5V.

    My confuse that is: whether I can user the output of TPS61023 can control En pin like my schematic, and It can run normally?

    Thanks and best regards.

  • +1 in reply to Anh Hoang
    TI__Mastermind 32350 points

    Hi Anh,

    OK.

    i think there should be no concern about the controller of EN. the sink and source capability of buffer seems strong enough for TPS61023.

    just a kind reminder. i still concern about the crash about the output. Joy  if you think that should be fine, ok, that will be fine.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Prodigy 50 points

    Hi Tao.

    Thanks for your support.

    I will try this design and hope that it running without problem Slight smile

    Thanks.