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BQ25618E: HIZ mode

Part Number: BQ25618E

Tool/software:

Hi experts,

My customer used BQ25618E for a doorbell product and want to use HIZ mode to test battery is good without removing adaptor during manufacturing. 

We have verified there would be about -150mA discharging to system in idle mode with only battery condition without adapter by measuring the current via DMM in series with battery. 

The issue is when having adaptor, and we could see system is good to bring up and battery also in charging status. Then when we issue HIZ command(REG00, change 81H), we would just see charging current become 0(status is no charging)  but what we expect to see is -150mA discharging from battery. It seems system is still powered by adaptor.

The other thing is when we add extra load at system by e-load e.g. 100mA, we could measure battery discharging -100mA now. 

Do you have any idea what might goes wrong? 

Schematic:

Original register config:

Regards,

Allan

  • Hi Allan,

    When VBUS is present, could you please help to provide the following before and after HIZ is enabled?

    1. The charger operating conditions such as VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS.
    2. All the register readings. The register readings help to understand the charge operating status and fault conditions if any.

    Thanks,

    Ning.

  • Hi Ning,

    I don't yet have all the information. Please see below what I have now.

    VBUS is 5Vdc, VBAT is 3.8V.

    Do you have any idea what might goes wrong? 

    Could you please clarify if the HiZ mode works out when adapter plugged in on the EVM?

    Regards,

    Allan

  • Hi Allan,

    The only functionality with HIZ that matters is when the adapter is plugged in. HIZ should work with adapter. Please send all the register readings as requested (not just some of them). Please provide on a scope capture VBUS, IBUS, IBAT, and ISYS while this is happening. Also provide VBUS, IBUS, VBAT, and VSYS. Are you sure your load is drawing current when there is no battery discharge current? Is it possible for some reason it is not enabled?

    Regards,

    Mike Emanuel

  • Hi Mike,

    Although customer hasn't been able to provide all the registers and waveforms. Let me explain more about the waveform should approve there is actual load.

    Regards,

    Allan

  • Hi Allan,

    Again, I need the requested waveforms. It is possible the load is not enabled in HIZ mode which is why we do not see the draw. The waveforms should confirm that.

    Regards,

    Mike Emanuel

  • Hi Allan,

    We have not heard anything for a while. The thread is considered closed.

    Thanks,

    Ning.