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BQ25120: Not possible to enter Shipmode

Ole Gellert
Prodigy 50 points
Part Number: BQ25120

Hi,

I've seen others having the same problem regarding Shipmode: if the charger reports Fault, Shipmode cannot be entered!

In our application this happens when we remove our external source. During this, the charger reports VIN_UV (and STAT_0, STAT_1 = 11). Unfortunately, there seems to be a mechanism inside BQ25120 that prevents the chip to go into Shipmode as long as a Fault is present. 

We enter Shipmode by writing 0x20 to register 0x00. This works fine as long as there are no faults. Faults occur when the input voltage is slowly decreasing - even when reaching 0V the fault is still present.

My questions:

is there a way to clear the Fault without having to manually plug/unplug a power source?

or best, can we force Shipmode?

Thanks

Ole

  • 0
    TI__Genius 12475 points

    Ole,

    Is your CD pin high?

    Could you share a little more info on the procedure and the code? Also any oscilloscope captures will help. 

    I have replicated your scenario on the captures below and I can go into ship mode with I2C no VIN and VIN in VINDPM as you can see below. 

    regards,

    Gautham

  • 0 in reply to Gautham
    Prodigy 50 points

    Thanks for your reply, Gautham.

    I have som more info and hopefully you may be able to replicate:

    - Took the standard bq25120 eval board: BQ25120EVM-731

    - Vbatt=3.7V, Vin=4.8V

    - CD jumper open (J7) => charging

    - Plug/unplug Vin in order to cause some Vin noise - after each cycle wait a second or two. Look for battery consumption of app. 740uA => Error state.

    - After a few tries, charger went into error/unknown state (leave power disconnected afterwards). The I_batt app. 740uA!

    - Plugging J7 in has no effect in that state - it's possible to communicate with the charger anyhow.

    - In the error state, the charger will report Fault in BOTH status AND VIN_UV. Normally Status will go to "Ready" when VIN_UV goes to "Fault"

    - Attached images shows the error state and also Vin w. noise (bq25120_error.png and vin_noise.png)

    - Toggling VINDPM will toggle status (Fault/Ready), but the unknown state is maintained.

    - I'm not able to bring the charger out of this unknown state - only by manually applying in Vin

    - I've also tried to turn off SW (1.8V). However, it will re-enable after a while (probably by the WDT). It seems the charger thinks that Vin is still present.

    - I was also able to bring it into the unknown state by slowly decreasing Vin. At about 3.5V it may enter this state. However, this may be a little hard to replicate.

    - In our application we see a little glitch on Vin due to load being disconnected. This causes the unknown state every time. (see vin_appl.png)

    Your support is appreciated - best regards

    Ole

  • 0 in reply to Ole Gellert
    Prodigy 50 points
    Hi,

    is there any solution to this unfortunate behaviour of the charger?

    /Ole
  • 0 in reply to Ole Gellert
    TI__Genius 12475 points

    Ole,

    Thanks for the plots. This certainly helps. 

    This is most likely due to the noise present on the VIN unplug. To test the theory out, would you be able to lower the VBATREG to 3.6V + Disable VINDPM and then unplug VIN to see if you are still stuck in this mode?

    As a noisy VIN unplug occurs and the device is going <VINUVLO and >VINSleep  very quickly this could happen. 

    We are working towards updating the datasheet for the timing requirements and also are coming up with a new silicon that addresses this. 

    Thanks,

    Gautham

  • 0 in reply to Gautham
    Prodigy 50 points

    Thanks for your feedback, Gautham.

    I've tried your proposal in my application and in fact the problem goes away - seems the theory is correct!

    Charger now reports "Charge Done" and not "Fault".

    If you're going to update the silicon, I would like to address another problem regarding PMID and capacitance:

    - If the PMID capacitance is >47uF (app.) and Vbatt<0.6V then the SYS voltage will not come up and pre-charge is not enabled!

    - This can easily be reproduced on the eval. board as well:  add 47uF from PMID to GND, Vbatt=0V apply Vin=5V and check for Vsys

    - In our application I started out with C_PMID=22uF as recommended in the datasheet (+ app. 10uF elsewhere) and SYS startup became unstable

    - ILIM does not have any affect on this behaviour

    The situation with Vbatt=0V is a common case if the battery protection circuit has been triggered or first time power up. Battery protection ICs require a voltage from the charger to engage the battery @ first time startup.

    Due to this issue, you're quite limited with regards to the amount of circuitry/capacitance that can be supplied by PMID.

    Don't know if this should be posted as a separate issue, but I would appreciate if you could look into this simple test as well. 

    Thanks

    Ole

  • 0 in reply to Ole Gellert
    TI__Genius 12475 points

    Ole,

    I totally agree with you on this. The VBAT >1V was a recommendation provided on the datasheet but I agree with you on the protector open scenario. 

    I have evaluated this condition in extensive detail in the past. One of the scenarios I would recommend to evaluate is that the time it would take to discharge to under 0.2V. (this measurement would have to be done with a high impedance probe as the leakage on the probe will contribute a lesser time)

    Also we have a newer silicon we are planning to release soon which will address this along with a few enhancements. 

    Regards,

    Gautham

  • 0 in reply to Gautham
    Prodigy 30 points
    Can anyone find out about the possible timing of new silicon?
  • 0 in reply to Maxim Zakharov
    TI__Genius 12475 points

    Maxim,

    the new silicon is mass production ready end of this month. It is called the BQ25120A. 

    thanks,

    Gautham

  • 0 in reply to Gautham
    Prodigy 10 points
    Mr. Gautham, Hi
    What is the status of production BQ25120A? When will the chips go on sale?
    Regards
  • 0 in reply to Evgeniy Borodin
    TI__Genius 12475 points

    Evgeniy,

    We are on hold waiting for a few customers to respond to our PCN. We can sample in volume as of now. I will contact you offline regarding this. 

    thanks,

    Gautham

  • 0 in reply to Gautham
    Prodigy 50 points
    Gautham,

    as we are planning a new design, I have a couple of questions regarding the BQ25120A:
    - Any indications when it will be ready for MP?
    - Is is possible to get an eval. board with the BQ25120A for testing?

    Thanks - best regards
    Ole
  • 0 in reply to Ole Gellert
    TI__Genius 12475 points

    Ole,

    Certainly. Our MP date is to by this month. Wk3-Wk4 at the latest is when we want to make it available on our store. We can sample pre-RTM but if there is a way for you wait until MP, that would be great!

     For the EVMs, they will be ready around Wk3-Wk4 as well. The BQ25120A will be pin2pin and bom2bom compatible with the BQ25120. 

    Regards,

    Gautham

  • 0 in reply to Gautham
    Prodigy 210 points
    Gautham,

    Is the BQ25120A active? We are having issues with the BQ25120, also. The website says the BQ25120A is still at "PREVIEW". You were telling us end of May. Is there a different part we should consider?

    Kelly
  • 0 in reply to Kelly Hathaway
    TI__Genius 12475 points
    Kelly,

    Sorry for the delay. We finally got our PCN notice back (this morning!) and we can actually make it sampleable/ purchaseable on the website.

    I have been told that it should go out in 2 days but I will keep you posted.

    thanks for your patience!

    Gautham
  • 0 in reply to Gautham
    Prodigy 210 points

    Gautham,

    Thanks for the update. Can you also provide us with the information on the changes from the BQ25120 to BQ25120A?

    Kelly

    kelly.hathaway@iconfitness.com

  • 0 in reply to Gautham
    Intellectual 375 points

    The web page for BQ25120AYFPT shows as in stock.  But if you go to the store and try to buy some it says it is out of stock.  Any idea what the issue is and how to get some samples for prototyping?

  • 0 in reply to Denis Bohm
    TI__Genius 12475 points

    Denis,

    I am checking on this one. thanks for your patience! 

    Gautham