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TPS63060: tps63060 input capacitors below 20uF

Part Number: TPS63060

We are having some problems related to electrical consumption of an equipment project that uses a 9V alkaline battery, and we noticed that the input capacitors on pin 2 Vi are below the specified in the datasheet (20uF), due to batch variation or tolerance, my question is the following, at least the fact that they are out of specification, this can cause a problem that can impact the consumption of the equipment when turned off, or somehow damage the Ci (TPS63060)?

Thanks

  • Hi  Sliva.

    i do not think the consumption will be a larger one with less cap. i think it will be almost same.

    if the input is clear enough, with a smaller cap should be ok too for TPS63060.

    so , what is the actual capacitance now?  can you find any unexpected high voltage noise at the input?

    Regards

    Tao

  • Hi Thao.

    First of all thanks for the answer, today the capacitance is below the specified in the datasheet (20uF) this is due to component tolerance issues, and I have noticed that the consumption of the switched off equipment has increased randomly, as if something was damaging over time.

    In some devices that had this problem, the input capacitance was 15uF.

    Thanks

  • Hi Sliva,

    OK, could you tell me the value of unexpected consumption? input voltage is still 9V, right?

    Regards

    Tao

  • Hello Tao.


    Once again thank you for your availability.

    Yes, our equipment works with 9V input, and the expected consumption is from 9uA to 12uA, the equipment works for a long time and then starts with a "drift", we have already detected equipment with more than 100uA of consumption, when the equipment is turned off.

    Thanks.

  • Hi  Sliva,

    i think you mean the whole system, but not only the TPS63060 converter, right?

    so, can we gurante there is no load on the next stage? or can we meansure the consumption when next stage disconnected?

    Regards

    Tao

  • Hello TAO

    The expected consumption when the equipment is on is 20 mA, and when the equipment is off its consumption is 10uA, that is, we can consider the consumption of the input loop + the consumption of the tps in standBy.

    The consumption of the input loop is given only by a reverse biased diode that switches between a USB source or a 9V battery.

    The topology I'm using is the same as suggested in the datasheet, for 5V output.

    The issue is that I cannot find the problem and I detected that the input capacitances are below the specified in the datasheet, it is as if this fact were deteriorating the CI(TPS) over time.

    Thanks.

  • Hi  Silva,

    Sorry, seems i made a mistake, it is possible that have a consumption around 100uA with TPS63060.

    As the picture below, the maximum total consumption based the conditions below should be around 100uA, and the typical consumption should be around 50uA. so i am afraid mostly it is impossible you can get a 9-12uA consuption with TPS63060.

    Regards

    Tao

  • Hello TAO,

    When the equipment is off my EN is to ground, in the datasheet the quiescent current consumption is below 30uA.
    So I have consumption in 10uA.

    Thanks

  • The value of 10uF in Cin is crucial for the equipment to work, what would be its purpose?
    
    Thanks for the help TAO.
  • Hi  Sliva,

    OK, that is correct, the maximum shunt down current is 2uA.

    The input cap is used to make your input voltage stable as a filter. without this cap. the input voltage will be dirty and with some high spikes cause by parastic inductor(the cable from power supply and your board)

    Regards

    Tao

  • HI TAO

    I did some tests without the Cin capacitor at the input, the TPS is not starting, it's as if the behavior was not just a filter.

    Thanks.

  • Hi  Sliva,

    Actually, device start for a while, but as there is no cap at input, the voltage will be pulled down immediatly and the UVLO triggered and the device shunt down. you can still treat this cap as a filter.

    Regards

    Tao