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BQ24297: About USB detection

Part Number: BQ24297

Hi,

Data sheet states that BQ24297 is compatible with BC1.2.



However, is it compliant in the following situations?

The default setting is D+/D- floating status.

According to Table2,

・If DCD timeout (D+/D- floating), shift to non-standard detection judgment
・If unknown in non-standard detection judgment, set to power supply with default 500mA

With this default setting, if customer use a cable without D+/D- wiring, BQ24297 will not be able to respond correctly.

Could you tell me the stance of BQ24297 when using a cable without D +, D-wiring and ?





Thanks
Yusuke

  • Hello Yusuke,

    The charger will default to 500mA if there is nothing indicating the IINLIM on the D+/- pins (floating)

    From the datasheet:

    When DCD 0.5 sec timer expires, the non-standard adapter detection is used to distinguish three different divider bias conditions on D+/D- pins. When non-standard adapter is detected, the input current limit (REG0[2:0]) is set based on the table shown below and REG08[7:6] is set to 10 (Adapter port). If non-standard adapter is not detected, REG08[7:6] is set to 00 (Unknown) and the input current limit is set in REG0[2:0] to 500 mA by default

    Sincerely,

    Wyatt Keller

  • Hello Wyatt,

    Thank you for your response.
    I understand.

    Let me ask you additional questions about the content related to BC1.2.
    The charger will default to 500mA if there is nothing indicating the IINLIM on the D+/- pins (floating)

    For example, a USB cable that does not have a D ± pin will be recognized as floating.
    In this case, the setting will be automatically set to 500mA.
    This is a risk when assuming various cables.
    What detection measures should I take for USB cables that do not have a D± pin?

    Could you tell me the recommended additional devices and techniques?

    Best regards
    Yusuke

  • Hello Yusuke,

    The charger also has VINDPM, if you set both appropriately you should be able to accommodate an unknown adaptor without overloading it too much. Or you can always write a new IINLIM value after detection via I2C.  

    Sincerely,

    Wyatt Keller