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BQ24195L EVM can't charge over 500mA

S L61
Intellectual 780 points
Other Parts Discussed in Thread: BQ24195L

I am using BQ24195L EVM but I found it can never charge over 500mA.

I have tried use it without MCU, just in default mode. The result was the same. REG08 is 0xB4 REG09 is 0x00.  The STAT led is off.

Does anyone know what happened? 

  • 0
    TI__Guru**** 166916 points

    The default charge current is 2048mA.  So either the IC's input current limit (i.e. IIN-DPM) or your power source's output voltage droop (i.e. VIN_DPM) is reducing the current that the charger is taking.  What is the value of the resistance on the ILIM pin?  Is the input voltage seen at the IC's VBUS pin drooping below your expected voltage (default VINDPM voltage 4.36V)?

  • 0 in reply to Jeff F
    Intellectual 780 points
    Thanks for your reply.
    I use a 169-ohm resistor on the ILIM pin and the voltage at the VBUS pin is 5V (seen from multimeter)
  • 0 in reply to S L61
    TI__Expert 8690 points
    Does your application involve a USB 2.0 as input? The default USB 2.0 detection limits input current at 500mA. To draw more current (up to 1.5A), it must be a charging port.
  • 0 in reply to Steven Bangdiwala
    Intellectual 780 points
    I plan to use USB as input in future but now I use a charging port. By the way, if I short D+\D- while using USB as input, will it be detected as a charging port or still USB?
  • 0 in reply to S L61
    TI__Expert 8690 points
    According to USB Battery Charging Specification Rev 1.2, to detect a dedicated charging port (DCP), the adapter USB port must have a short between D+/D- not exceeding 200 ohms.
  • 0 in reply to Steven Bangdiwala
    Intellectual 780 points
    Thanks StevenB. Now I still use charging port but it seems something limit the charging current.
    I changed REG00 to 0x37 and REG05 to 0x8A via MCU I2C (I can see it successfully written). Other registers remained default setting. Still, I use a 5V 1.5A charging port and I discharged the battery to 3.1V. Things become a little different.
    When starting charging, I got REG08 = 0xB4, REG09 = 0x00. The STAT LED was off. The charging current never exceeded over 1A. The voltage seen at VBUS pin is 4.96V and 4.2V on BAT pin. Then I decreased the charging current to less than 800mA. The LED was on and I got REG08 = 0xAC, REG09 = 0x00. The voltage seen at VBUS pin is 4.33V and 4.0V on BAT pin.
  • 0 in reply to S L61
    Intellectual 780 points
    After several attempts, I find the reason. It seems the resistance of wire connecting battery and BQ24195L is too large (0.5 ohm). This prevents current going to the set value.

    Use good wires next time.