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TPS27081A with more supply options crashes the system

Maykel Alonso
Intellectual 285 points
Other Parts Discussed in Thread: TPS27081A, TPS22963C

Hello!


I'm designing a system with more than 1 power sources and in this system I use the TPS27081A load switch as switch to enable the power source. The problem I have is the following one:

When there is no power in pin VIN (0V), I select the off option (Switch off VIN and VOUT)  and there is power on the VOUT pin (5V) that comes from another power source, I see voltage in the VIN pin and the system crashes. So, the chip don not block the other power source.

I tried to solve using a diode in series in the Vout pin , but the best diode I found has a 0.35V voltage drop, so the Voltage in the system when I have these power source (5V) is of 4.65V. I need 5V to have the system working perfectly (charging circuit).


So, any of you could tell me a solution for this problem? Is htere another part to do this? Any suggestion?

Many thanks in advance.

  • 0
    TI__Genius 15780 points

    Hi Maykel,

    If my understanding is correct, then your system looks like the drawing below:

    When the load switch is turned off, there is a chance for supply 2 to be on and cause reverse current through the load switch. To avoid using a diode, you could use a load switch with an integrated reverse current protection feature.

    The TPS22963C is a 5.5V, 3A load switch which can be powered from VOUT to block reverse current when VIN = 0V. VOUT will need to reach 1V to power on the device, so the device will not block reverse current until then.

    Please let me know if this load switch would be a possible solution.

     

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Intellectual 285 points

    Yes, this is a posible a solution and I will implement.

    Thanks Alek