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TPS2663: Digital pot on ILIM to set current limit

Forrest Christian
Prodigy 10 points
Part Number: TPS2663

Tool/software:

We are planning on using a TPS2663x family part in an industrial application where we would like to be able to provide an adjustable current limit.  To achieve this, we are planning on utilizing a digital pot on the ILIM pin.  However, the datasheet is silent on the typical and maximum current expected out of the ILIM pin and as a result, we're unable to determine whether our selected digital potentiometer will work reliably.

My questions:

1) What is the typical and maximum current sourced out of the ILIM pin (such as in a temporary overcurrent situation)?  

2) Is there any TPS2663x-specific reason why a digital pot wouldn't work in this application?

Any other information about the behavior of the ILIM pin which we might find useful would be helpful as well.

  • 0
    TI__Guru* 79071 points

    Hi Forrest,

    By using digital pot you will change RILIM dynamically which is fine to use on ILIM pin. Based on datasheet equation you can calculate what current limit threshold device will be at for different RILIM. 

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Prodigy 10 points

    The problem I'm running into is this:

    Most (if not all) digital pots have a maximum voltage when referenced to Vss for voltages on their digital pot outputs.   There is no data that I can see in the TI datasheet to indicate how much current is sourced out of the ILIM pin or any other data that I can use to determine the expected voltage range on ILIM, other than an absolute maximum rating which is useless as that is more about applied voltage, not current sourced from the device.   

    In addition, digital pots have a certain amount of leakage current, often in the nA range. Without knowing the typical current sourced out of the ILIM pin it is impossible to determine if the digital pot leakage current is in excess of what will work for this application.

  • 0 in reply to Forrest Christian
    TI__Guru* 79071 points

    Hi Forrest,

    Let me check on this.

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    TI__Guru* 79071 points

    Hi Forrest,

    Let's chat on private messaging.

    Regards

    Kunal Goel