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BQ25629: OTG Boost not working

Lane Brooks
Prodigy 100 points
Part Number: BQ25629

Tool/software:

In our design, we are relying on OTG boost to drive 5V on PMID and VBUS...

When we set reg 0x18 charge_control_2 to 0x44 to turn on the EN_OTG bit, nothing happens with the PMID and VBUS voltage... They stay at about 0.5V below the VBAT.

When we set reg 0x18 charge_control_2 to 0x84 to turn on the EN_BYPASS_OTG, again nothing happens to PMID or VBUS... they stay about 0.5V below VBAT.

When we set reg 0x18 charge_control_2 to 0xC4 to turn on both EN_OTG and EN_BYPASS_OTG, then PMID and VBUS go to the VBAT voltage.

How do we get the BOOST to enable?

Lane

  • 0
    TI__Guru 57331 points

    Hi Lane,

    Has all the boost operation conditions listed on 8.3.6.1 Boost OTG Mode are met?

    1. What the VBAT pin voltage and OTG load current when set EN_OTG=1?

    2. Do you test with a real battery or battery simulator?

    3. What are all the register readings after setting EN_OTG=1? Any fault??

    Thanks,

    Ning

  • 0 in reply to Ning T
    Prodigy 100 points

    See my responses in line below:

    > Has all the boost operation conditions listed on 8.3.6.1 Boost OTG Mode are met?

    We will take some measurements to make sure....

    1. What the VBAT pin voltage and OTG load current when set EN_OTG=1?

    VBAT is a fully charged battery, so around 4.2V. There is no OTG load as of yet.

    2. Do you test with a real battery or battery simulator?

    Real battery.

    3. What are all the register readings after setting EN_OTG=1? Any fault??

    Which registers would you like us to check the status of?

  • 0 in reply to Lane Brooks
    TI__Guru 57331 points

    Hi,

    All register readings would be ideal or at least the following registers.

    Thanks,

    Ning.