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BQ25798: Unexpected behaviour in MPPT mode

Christoph Dunkel
Prodigy 110 points
Part Number: BQ25798
Other Parts Discussed in Thread: USB2ANY

Hi,
I have made an EVAL board for this chip and connect and control it with TiChargerGUI and usb2any.

The basics are all working as expected.
However in MPPT mode I see some unexpected behaviours.

When playing around with VOC_DLY (50ms) and change it back, then keep change the input voltage the unit stops adjusting the MPPT value completely.
Another issue I found is that after some time where no input voltage was applied, it then raise slowly, it fails to start charging. After a quick Vin power cycle however it comes back normally.

To me it somehow seems that the pro production ICs still have some issues here?
Device Revision is 7.

Thanks for any help

  • 0
    TI__Mastermind 40305 points

    Hello,

    Can you please check to see what your MPPT VOC Measure Period is? If you lower the input voltage while already in MPPT with VINDPM regulation, the part will stop taking in current because you fall below the VINDPM value. It will resume once the part remeasures the open circuit voltage. This is because the MPPT VINDPM is only updated every MPPT VOC Measure Period.

    For the second issue, can you please describe in more detail what voltage you are applying that does not start charging?

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.