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BQ25890: I can't charge (Ibat zero) with Maxcharge HVDCP charger

andres_dalmati
Expert 1110 points
Part Number: BQ25890
Other Parts Discussed in Thread: BQSTUDIO

Hi,

I made my own device with a TM4C123G, BQ25890 and many other components. This board has a USB connector and SD card to log data.

When I plug a charger (Motorola Turbo Charger). BQ25890 detects a MaxCharger device but Ibat never changes (and of course doesn't charge the battery).

Why ICO always is "in progress"? Vindpm is 11.1V but Vbus is 9.1V

Do I need change Vbus to 12V with PUMPX_UP bit in REG09?

With other chargers I don't have problems.



Thanks in advance.

Andrés

  • 0
    TI__Mastermind 31840 points

    Hi Andrés, 

    On the BQ25890 when a MaxCharge adapter is detected it will either detect a 12V input or a 9V input. You state Vbus = 9.1V, can you please verify that your adapter (Motorola Turbo Charger) is meant to operate as a 9V source or 12V? 

    Additionally can you please provide all register values? The image you include shows some relevant information, but not all. 

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Expert 1110 points

    Hi Garrett,

    Best Regards!

    Andrés

  • 0 in reply to andres_dalmati
    TI__Mastermind 31840 points

    Hi Andrés, 

    Thank you for the additional information. The reason your device is not charging is because the device is in VINDPM due to Vindpm being set = 11.1V and Vbus only = 9.1V. In this condition switching is stopped and the device will not charge.

    The root cause appears to be that the input type detection is not fully compatible with your Motorola Turbo Charger. The adapter handshake is attempting to raise the input voltage up to 12V, hence why Vindpm is set to 11.1V, but the Motorola adapter voltage does not rise up above 9V. 

    This previous E2E thread provides additional information explaining how the BQ25890 will not work with all types of HVDCP adapters. https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/790857/bq25890-can-maxcharge-be-compatible-with-qc3-0-or-qc2-0 

    PUMPX will not work to raise up the adapter voltage, as it is designed for a different protocol. An easy work around is to set FORCE_VINDPM = 1 (REG 0D bit 7) then manually program VINDPM (REG0D bits 6:0) to a value lower than 9V. Once the device is no in VINDPM mode the battery should be able to begin charge. 

    andres_dalmati said:
    Why ICO always is "in progress"?

    Once the device is out of VINDPM the input current optimizer should be able to complete. 

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Expert 1110 points

    Hi Garrett,

    Thanks for your quick answer. It's very clear and straightforward.

    I have another question. I used BQ25890EVM_664 with the same charger and battery. I obtained this results.

    Vbus = 12.1 V

    Vindpm =11.0V

    Apparently the handshaking is OK, so I can charge the battery ( Ibat = 750 mA )

    On the other hand why Ibat is 750 mA with Ilim = 1.5A?

    Thanks in advance

    Andrés

  • 0 in reply to andres_dalmati
    TI__Mastermind 31840 points

    Hi Andrés, 

    Good to hear that the handshake is working properly.

    Based off the results you provided it appears the IC is charging at 750 mA due to battery being close to fully charged (Vbat = 4.204V). When the battery voltage is close to the Vreg value the charge current will decrease as it is in the constant voltage part of the charge cycle. If you perform the test again with your battery further discharged, for example 3.8V, I would expect Ibat to be closer to your ILIM setting. 

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Expert 1110 points

    Hi Garrett!

    Thanks for your answer.

    The handshake is working properly in the BQ25890EVM_664 (I'm using bqstudio), but it is not working properly in my custom board. I don't understand why this is happening.

    If my battery is completely discharged (using the same charger and BQ25890EVM_664) Ibat is 1.85 A and BQ25890 is in IINDPM (because Ilim is 1.5A). It's also weird.

    Thanks in advance.

  • 0 in reply to andres_dalmati
    TI__Mastermind 31840 points

    Hi Andrés,

    I would recommend comparing the EVM schematic with your custom board design to identify why the handshake is not working on your custom board. The EVM schematic can be found in the EVM user guide, which can be downloaded from TI.com and I have linked here. BQ25890EVM-664 Evaluation board | TI.com

    andres_dalmati said:
    If my battery is completely discharged (using the same charger and BQ25890EVM_664) Ibat is 1.85 A and BQ25890 is in IINDPM (because Ilim is 1.5A). It's also weird

    This is the expected behavior assuming ICHG setting (REG04) is still set to 2.048 A (default). BQ25890 attempts to charge at 2 A, but IINDPM caps it at 1.85 A. If you lower your ICHG setting below 1.5A the IC will exit INDPM mode and charge at the set ICHG value. 

    Best Regards,

    Garrett