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BQ24298: No Charge Termination after Wakeup from Shipping Mode

Christoph Beck
Prodigy 10 points
Part Number: BQ24298

Dear Community,

any help here is greatly appreciated.

The system

We have a handheld device and very typical usag. Use on battery power until it is dead. Charge. Repeat. We hava a single cell LiPo and the BQ24298 controller. With a µC we can read from and write to the registers, set pins, etc. The design is in the market for quite some time and charging (low/high charge), discharging worked fine. We can see the correct CHRG_STAT in REG08.

The change - shipping mode

In our last update we introduced the Shipping Mode to allow longer periods in stock. At the end of our production line we send activate the Shipping Mode and the device is then shipped to the customer.

The problem

Our customer receive the device still being in Shipping Mode. Then we ask them to plug in USB to wake the device up. After power-up the device charge es battery as specified, but CHRG_STAT in REG08 will never transition from Fast Charging to Charge Termination Done. And this is the flag we react on in the GUI.

How to recover

We experienced that a power cycle of the BQ24298 chip resolves the problem (unplug USB and battery for some sec).

Does someone have an idea what we're doning wrong? Do we need to set/reset a flag during wake-up from Shipping Mode? Has anyone experienced the same problem?

Many thanks,

Chris

  • 0
    TI__Expert 4465 points

    Hi Chris, 

    Just enabling shipping mode will not cause this behavior, the part were removing the battery fixed the problems points to a wrong configuration being set on the device before enabling shipping mode.

    1. Do you have the registers configuration you had on the previous firmware vs the registers configuration of the updated one? 
    2. Is it possible to provide the registers status while the device is not terminating? This will help us determine if there is a fault preventing termination.
    3. Can you also provide the charger portion of the schematic?

    Best regards, 

    Arelis G. Guerrero 

  • 0 in reply to Arelis Guerrero
    Prodigy 10 points

    Hey Arelis,

    appreciate your quick help. I did a printout of all registers.

    The only register we set is the charge current control register. Limiting the charge current to 1.5A.

    Especially REG05 looks suspicous, no?

    Kind regards,
    Chris

  • 0 in reply to Christoph Beck
    TI__Expert 4465 points

    Hi Christoph, 

    Yes, the REG05 when is equal to zero is disabling termination. Therefore that'll explain why termination is not happening. Are you sure your firmware is not overriding this register to zero?, keep in mind this same register has the WATCHDOG timer bits which you need to configure to disable to be able to enter shipping mode. 

    Regards, 

    Arelis G. Guerrero  

  • 0 in reply to Arelis Guerrero
    Prodigy 10 points

    Thanks for the hint with REG05. It was exactly as you described.