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TPS2590 Iflt - Ilim spread

Bryan Capdeville
Prodigy 80 points
Other Parts Discussed in Thread: TPS2590

We are using the TPS2590 in an application where the spread between I fault and I lim needs to be as small as possible.  Page 7 of the data sheet warns that Ilim needs to be larger than Iflt even considering tolerances.  Do these "tolerances" include the min to max range of Ilim and Iflt on page 3?   In my calculations, do I need to use Iflt max and Ilim min or can I expect these values to move in the same direction?  (i.e. if Iflt for the part is closer to the min, I can expect Ilim to be closer to it's min as well)

  • 0
    TI__Guru 50040 points

    Hi Bryan,

    What is the application and what is the threshold they desire for Iflt and Imax? The values in the data sheet are a prescribed set of resistors. Your assumption above is a good approach if you want to narrow the gap between fault and max. Keep in mind if the current limit is at maximum, then Vout will pretty much get divided down by the current limit.

    Regards,

  • 0 in reply to JCHK
    TI__Expert 3075 points

    Bryan,

     Another approach for a precise current limit with the 2590 is to set Ilm lower than Iflt and ground Ct. When so configured the 2590 will behave as a thermal switch and limit any overcurrent until the 2590 goes into thermal shutoff. It will continue to cycle as the overtemp shutoff circuit cools down, turns on, and heats up again. If this type of behavior is acceptable in the application then it might be worth considering. Ct has to be grounded since it will never start to charge...since Ilim will never be reached.

  • 0 in reply to Jim Bird
    Prodigy 20 points

    Jim Bird said:

    Bryan,

     Another approach for a precise current limit with the 2590 is to set Ilm lower than Iflt and ground Ct. When so configured the 2590 will behave as a thermal switch and limit any overcurrent until the 2590 goes into thermal shutoff. It will continue to cycle as the overtemp shutoff circuit cools down, turns on, and heats up again. If this type of behavior is acceptable in the application then it might be worth considering. Ct has to be grounded since it will never start to charge...since Ilim will never be reached.

    Hi,

    I'm going to use this approach hence I would like to get more info about the setup of the 2590.

    Up!!

     Please someone who may give some numbers just as example to understand how setting-up this unusual approach

    Thanks

    Walter