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BQ24195 can't provide the designated current

S L61
Intellectual 780 points
Other Parts Discussed in Thread: BQ24195

Dear all,

I am using BQ24195 and use it to charge my battery. A USB power source(5V 2A) is plugged in. However, the current it provides is less than the set value. I did the following procedures:

  1. Write 0x1B to REG01 (Power-On Configuration Register)
  2. Write 0x36 to REG00 (Input Source Control Register)
  3. Write 0x8A to REG05 (Charge Termination/Timer Control Register)
  4. Write 0x00 to REG06 (Thermal Regulation Control Register)

The REG08 is 0x00 and the current I measured is about 90mA. It seems current limit was forced to set to be 100mA and the BQ24195 didn't detect the USB source.

Is there anything wrong? Thanks.

  • 0
    TI__Expert 8690 points

    Hi S L61,

    Seems that D+/D- detection reads unknown adapter. What is connected to the D+/D- pins of the bq24195? It could also be that every time you plug in the USB, the device reads unknown and goes back to 100mA.

    ILIM pin should be grounded (control input current limit through register) or have a resistor value that gives you 2A current limit.

    Even if unknown adapter is read, you can override input current limit to 2A just like you did. I would do step 3 first before anything else (disable watchdog).

    Thanks,
    Steven

  • 0 in reply to Steven Bangdiwala
    Intellectual 780 points
    Thanks for your reply. The D+/D- pins are float when no USB power source plug in and ILIM pin is connected to a 167 ohm resistor (nearly 3A current limit). I can override the input limit to 2A (the current is about 300mA) after I found the current went back to 100mA but I still want the device to detect my USB well. Thanks.
  • 0 in reply to Steven Bangdiwala
    Intellectual 780 points

    Hi StevenB,

    Today I found the fault register REG09 = 0x23. However, I don't understand what it means since the fault number 3 is not described in data sheet. The problem still exists.

    Is it help to short D+/D- pin with a 200 ohm resistor? Thanks

  • 0 in reply to S L61
    TI__Expert 8690 points
    Hi S L61,

    D+/D- of the bq24195 should be connected to the D+/D- on the USB port you are using to connect the adapter, so that D+/D- detection can happen. If you are only working with charging ports, then a short with a resistance not exceeding 200 ohm will work (does not have to be 200 ohm, only that it should not exceed this amount).

    The fault register REG09 = 0x23 (00100101) problem could comes from not using the correct resistance values on the TS pins. Read pages 18-19 of our datasheet to know more about this.

    Thanks,
    Steven
  • 0 in reply to Steven Bangdiwala
    Intellectual 780 points
    Thanks. In fact, I need to use the D+/D- to detect both charging ports and USB host. Will it work if I short D+/D- pin with a resistor?
  • 0 in reply to S L61
    TI__Expert 8690 points
    Hi S L61,

    In order to have D+/D- detection to work for both charging port and USB host you need to connect D+/D- to the USB port on the device. Look at how they are connected in page 34.

    Thanks,
    Steven