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BQ25015 - Charging protection

frederic douit
Intellectual 480 points
Other Parts Discussed in Thread: BQ25015, BQ24072, BQ24040, BQ25100, BQ24232, BQ25101

Hello,


I would like to charge a Lipo of 400 mAh with the BQ25015.

For this Lipo, the recommended max charging current is 400 mA.

If I set the ISET2 to high to get charging current between 400 and 500 mA, is the BQ25015 detecting that it can't go further than 400 mA? or is it the battery that limit the charging current? or is the BQ25015 will charge at 500 mA and my battery will blow up to my face? 

If I set ISET2 to low, it will charging at 100 mA, it's too slow.

Thank you for your lightnings

  • 0
    TI__Mastermind 19430 points

    Please refer to the electrical characteristics table on page 3, the maxium char current spec is 500mA. What is your charging requriement? Is duo input (AC and USB) a requirment? Or you are just charging from one input source?

    Proper charge current should be defined by the battery spec. The charger charging current can be set by external resistors to the desired level within the spec range. For safe charge, please follow the battery spec.

    If you are looking for higher charge current, please take a look at bq24072/3/4/5/9, this famliy of device supports power path management and up to 1.5A charge current.

  • 0 in reply to Jing Zou
    Intellectual 480 points

    Thank you for your answer,

    I use only usb charging,

    If I understand, I can choose the charging current by external resistor within the 2 ranges :

    80 - 100 mA

    400 - 500 mA

    For my battery, it's 200 mA, it's only possible by AC right? I can't by usb? or only 100 mA?

    Is there a equivalent of BQ25015 with the possibility of 200 mA by usb?

    thank you for your help

  • 0 in reply to frederic douit
    TI__Mastermind 19430 points

    If you are looking at a charger with out power path, I recommend bq24040 or bq25100.

    If you are looking at a charger with power path, please take a look at bq24232.

     

  • 0 in reply to Jing Zou
    Intellectual 480 points

    Hello,

    Thank you for your answer and sorry for the delay of my reply, time flies.

    I was looking at the doc of the BQ24040 and saw that it had the same specs. (100mA and 500 mA of charging current).

    After some research, I slowly drifted to wireless charging device (Qi) and I lost myself... and finaly, I understood that Qi was not suitable for my 400 mah battery since that Qi is for at least 1000 mAh batteries..

    I went back to classic charging and looked at BQ25100 that you mentioned. This one is good (250 mA) but..... I need status output options to monitoring the charge. As I'm writing this message, I just saw that BQ25101 has a led driver for monitoring charge... but I can't see information about that in the documentation..

    Do you know where to find this information?

    Thank you for your help

  • 0 in reply to frederic douit
    TI__Mastermind 19430 points
    1. the USB100 and USB500 on bq24040 is for input current limiting. If you set the input current limit to 500mA and set the charge current at 200mA, the battery will be charge at 200mA assuming a valid input source is attached.
    2. bq25101 has /CHG pin which is a charge status indicator. You can find the detail description on datasheet page 15 section 8.3.2 and 8.3.3
  • 0 in reply to Jing Zou
    Intellectual 480 points
    Thank you a lot!
    I missed that, bq24040 can charge between 10 and 1000 mA. I inverted with an other doc wich said between 400 and 500 mA.
    Now I have 2 solutions, thank you very much!
  • 0 in reply to frederic douit
    TI__Mastermind 19430 points

    One more note on the "Qi was not suitable for my 400 mah battery since that Qi is for at least 1000 mAh batteries.."

    The WPC1.1 (Qi) is for UP TO 5W, which means it also supports output current lower than 1A at 5V.

  • 0 in reply to Jing Zou
    Intellectual 480 points
    Oh yes you are right.
    For now I only found 2.5W. I have to search deeper, maybe I can find 1W.
  • 0 in reply to Jing Zou
    Intellectual 480 points
    I came back,
    I am wondering what is the difference between ac charging and usb charging?
    Can I use usb plug routed on the ac pin input?
    With that I can get the ac outpout current at any value I want by putting a resistor on iset1.
    Am I missing something?
    thank you for your help