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BQ24266: Current Limit Programming Inputs

Part Number: BQ24266
Other Parts Discussed in Thread: BQ25890

Hello Sir,

I am interested about this IC.

My application is to support a battery in a system and input from USB or quick charging mode by an adapter. Take a look on this application circuit, I want to use this circuit without MCU control.

1. According to datasheet page 21 Device Functional Modes, can I set IUSB1..3  GPIOS to ground?

2. What to do with other mode of operation? Can I use VIN to one of the IUSB?

3. Looking at the datasheet, 30V Input Rating with Over-Voltage Protection do exist,  maximum Input current can be 2.5A, QC adapter allows power according to load request then  its not a problem but , still my co worker confused about the charger ic side voltage protection, kindly clarify it.

  • Hi Mubdiul,

    Regarding 1, tying all three IUSB pins to GND sets the input current limit to only 100mA.  What is the output current rating of the power source you intend to use for the charger?

    Regarding 2, since IUSB pins are only rated for 5.5V, I only recommend tying them to VIN if VIN is 5.5V on less.  If a battery will always be present, you can connect them to the battery or you can connect them to DRV.

    Regarding 3, the absolute maximum voltage of 30V is to protect against overvoltage from voltage spikes during plug in.  The maximum operating voltage for the charger is 13.5V, anticipated from a 12-V +/-10% wall adapter.

  • Dear Sir Jeff,
    Thank you very much to support here.
    My application shows in another post, e2e.ti.com/.../652252


    If you can see on the diagram,

    Regarding 1, its galaxy NOTE 5 type smartphone with USB 2 application . I am considering both the phone and charger IC those gets power from a PC or QC/PD type source, that might be 5V /2A power from adapter but, in quick charging mode, 9V/ 2A power.Let us assume the battery is Li-ion 3.7v 4.07Wh to 4.2v. I think, we need both 100mA and 500mA.

    Regarding 2, its very important point. My co worker think that in quick charge mode 9v would be available at VIN. Since battery is less then 5 v so it will not be good idea to connect ISUB to BAT. Let me see how I can implement DRV.

    Regarding 3, yes, I understand it.

    In my previous design by n www.ti.com/.../bq24074.pdf I have use EN1 and EN2 from the previous chip, but those logic were from main MCU.

    Since we don't want to use any firmware here, could you suggest me any logic converter which will operate different (100mA and 500mA) setting?

    Or depending on current sensing they will chose the port?
  • Hi Hasan,

    Regarding 1, I am not aware of a standalone chip that can perform both USB BC 1.2 and HVDCP (like QC) detection.  However, all of our chargers have VINDPM feature which will prevents the charger's input voltage from drooping by further lower input current limit if it pulls more current from the power supply than its IINDPM feature (input current limit) is configured for.  If your HVDCP power source uses D+/D- to negotiate up from 5V to 9V then you would need a charger with D+/D- and HVDCP.  The charger family we have with both features are bq25890/898D/895/890H.  Although ideal for host control, this IC family can work standalone with fixed charge current of 2A, limited by the input current limit set by the ILIM pin.  This family also has the ICO feature which will determine the optimal input current setting of the power source.  For example, D+/D- might detect DCP, setting IINDPM register to 3A but you could clamp the maximum input current limit using ILIM to 2A. Then, if the charger pulled too much current, causing the charger to hit VINDPM, ICO would activate and reset IINDPM register to a lower setting that prevents hitting VINDPM again.

         

  • Dear Sir Jeff,

    This time you have posted nice and informative explanation!
    Thank you once again.

    I understand the functionality of VINDPM and IINDPM as those compensate suitable current and voltage limit.
    I am not considering D+/D- in my circuit operation, because in charging mode , these pins are not contributing!


    If you look on the diagram you would see, the current path is divided in 2 ways!

    In QC mode, the adapter has 9v/1.67A, after connected the Galaxy note 5 we saw 1.23A is operating.

    Right at the moment, we have faced a problem that is the charger ic side current will be 0.44A to 0.30A( depending on the supply current from adapter or over voltage and current protection).

    The battery we gonna use has 3.7V 2200mAh in actual spec capacity. (sorry for my previous information)
    It will take long time to charge the battery!
    So, I am thinking that battery charging capability will not be appropriate.

    All universal adapter and PC usb current rating does not match with our system!