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BQ24196: Questions on the usage of BQ24196

Wenle Liang
Intellectual 270 points
Part Number: BQ24196

I have made a PCB to test the BQ24196. But I have met several questions.

1. The maximum charge current of my board for my phone is 800mA while the nominal maximum charge current of BQ24196 is 2.5A. But I moved BQ24196, the charge current is normal. The schemic can refer to below.

2. When I  read the register REG08 of the chip, I find its values change unexpectedly  after I power up my PCB for about 20 seconds.  For example, PG _STAT changes from 1 to 0 while CHRG_STAT changes from 10 to 01.

  • 0
    TI__Expert 8230 points

    Hello Wenle,

    Please see my comments below:

    Wenle Liang said:
    The maximum charge current of my board for my phone is 800mA while the nominal maximum charge current of BQ24196 is 2.5A. But I moved BQ24196, the charge current is normal.

    Can you please clarify this statement? If the charge current needed for the application is 800mA, the I2C register REG02[7:2] need to be modified accordingly to change the fast charge current to 800mA.

    Wenle Liang said:
    When I  read the register REG08 of the chip, I find its values change unexpectedly  after I power up my PCB for about 20 seconds.  For example, PG _STAT changes from 1 to 0 while CHRG_STAT changes from 10 to 01.

    Can you please elaborate on your test setup? What's the battery voltage, system current, register settings? Are there any faults being reported by the device during this test?

    Regarding your schematic:

    • I noticed you have labels on PSEL and PG pins leading to USB_DM and USB_DP. Are these pins being connected to a USB port's D+/D- lines?
    • What's your inductor's saturation current?

  • 0 in reply to Fernando Lopez
    Intellectual 270 points
    Hello Fernado,
    For your first question, I need the current to be at least 2A, but when I put BO24196 into my circuit loop, the current decreases to about 800mA. I didn't change the I2C register REG02, so the register value must be default.
    For the second question, I only read the value without any write operation. The battery voltage is 3.9 V with 800 mA system current. So the changes of register value are not faults?
    Thanks.
  • 0 in reply to Wenle Liang
    TI__Expert 8230 points

    Hello Wenle,

    Have you verified if the device is either in INDPM or VINDPM? Do you have a load at SYS as well? If so, how much?

    The bq24196 is a power-path device, which means that the system power will be prioritized over the charge current if the adapter cannot provide the necessary power as the system load increases.

    Please read the following registers during your tests: 

    • REG08, this will tell you the state of your system, in particular, whether the charger is in DPM and is reducing the charge current.
    • REG00: this register holds the input voltage limit and input current limits. Please verify these match the expect limits. For example, your ILIM is set for 1.7A, but since your PSEL pin is connected to what I'm assuming is a D- line, the voltage at the line might be too high and forces the PSEL logic high which corresponds to a 500mA current limit.