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BQ25886: Input current limit

Filip Tot
Prodigy 50 points
Part Number: BQ25886

Hi,

I have setup ILIM to 1.2A but I'm not sure what will happen if we plug USB from the PC, will it try to draw that current?

How I can protect that kind of input, how to properly use D+/D- OTG setup, but to have 1.2A when the adapter is plugged and there is no D+/D-? Do I need some external voltage divider to set the input current in some range, but what function has ILIM then?

Regards

  • 0
    TI__Mastermind 40275 points

    Dear Filip,

    The charger input current is limited by the lower of the ILIM pin limit or the input source detection (please note that ICO will be run if a DCP is connected). If you plug in a USB SDP with a current limit of 1.2 A on the ILIM pin, your input current limit will be 500 mA from the USB SDP. If however, you plug in another adapter, the table in the datasheet in Section 8.3.3.2.1 on page 15 will detail the input current limit corresponding to each type of adapter. If you would like to achieve higher than 1.2 A, you would both need to set the ILIM pin limit higher and plug in an adapter that is rated for a higher current.

    Thanks,

    Mike Emanuel

    Please click "This resolved my issue" button if this post answers your question.

  • 0 in reply to Michael Emanuel35
    Prodigy 50 points

    Hi Michael,

    thank you for the replay,

    I saw the table of dividers but I'm not sure what are those dividers, where are placed? Also, I saw the table of TH voltages on D+/D- but don't know where I will get it, and how. Does it work with adapters that have some USB chip/communication, and if it doesn't have it then it's "unknown 5V adapter", and the output current will be 500mA?

    If I plug the usual 5V adapter, like for mobile phones, it will have just Vbus and GND, is this kind of adapter is unknown?

  • 0 in reply to Filip Tot
    TI__Mastermind 40275 points

    Dear Filip,

    You do not need to connect these dividers. They are inherent to certain known adapters and how they are terminated. If you plug in one of these adapters and have your D+/D- lines connected the charger will be able to tell if one of these dividers is connected. If the charger cannot detect the type of adapter, it will identify it as an "unknown 5V adapter" and will set the input current limit to 500 mA.

    It is hard for me to say what the "usual adapter" is. If it is not one of the standard ones the charger can detect, it will be unknown.

    Thanks,

    Mike Emanuel

    Please click "This resolved my issue" button if this post answers your question.