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BQ25120A: Starting in Ship Mode?

Dennis Ryu38
Prodigy 60 points
Part Number: BQ25120A

While the BQ25120A is in default settings, we have the battery connected and the power line is feeding other modules including the microcontroller.  As such, the microcontroller is supposed to be advertising at a constant period, but for some reasong this is not happening for us quite often.  This issue is not consistent with our devices - there are some that work fine but some do have this same issue.  But when we feed the DC power through the IN pin, the devices begins to function normally.  Currently we implemented an NFC coil so once we scan it on another powered coil the device begins advertising as intended.  I attached a diagram of our schematic for reference.

Would there be any possible errors on our schematic?  It is my understanding that the default setting of the device is that they are not in ship mode.

  • 0
    Prodigy 60 points

    Sorry, this is the correct schematic we are currently using

  • 0
    Prodigy 60 points
    Could it be because We connected PMID-VINLS when SYS is 1.8V and our LS/LDO is also 1.8V? It is supposed to be SYS-VINLS correct? But how would this affect the start-up of the PMIC?
  • 0 in reply to Dennis Ryu38
    TI__Genius 12485 points
    Dennis,

    When you plug-in the battery, you are seeing some devices start up and some that go to Shipmode- is that correct?

    When the battery is plugged in, it is always good to hold the /MR button to prevent any race between the button and the battery pin.

    Could you clarify a little more on the VIN present condition? Are you saying that when the coil is powered ON, you are always seeing the device startup?

    Regards,
    gautham
  • 0 in reply to Gautham
    Prodigy 60 points

    Hello Guatham,

    Thanks so much for the prompt response.

    Yes, when we plug in the battery we are seeing some devices that start-up and some that don't.  We are guessing they go into Ship Mode because they don't respond until we supply a DC voltage at the IN pin.

    Could you elaborate on what you mean by the race between the button and the battery pin?  It may be we are missing something when we planned our power sequence.

    For the batteries that go into start-up upon attaching the battery, we see that the SoC is constantly advertising and looking for a connection.  For the devices that seem to go into Ship Mode. they are returned to the intended startup once we power the coil attached to the IN pin, and after that they will advertise.

    If you are looking for any specific edge cases or scenario please do let me know!

    Thanks so much,

    Dennis

  • 0 in reply to Dennis Ryu38
    TI__Genius 12485 points
    Dennis,

    The /MR is a pin that is pulled up internally and it is a high value resistor (to lower leakage). Depending on the slew on VBAT, capacitance on /MR- the slew on /MR could be "seen" differently than the VBAT internal POR thresholds. In these cases, we will rather go into Shipmode than to turn the device ON partially.

    If you were to try the experiment with /MR pulled low and then insert the battery, you should see a more consistent behavior.

    Is your product designed to have the battery being ON and OFF?

    Let us know if you have any questions.

    Regards,
    Gautham.