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bq24190EVM

Joe Rule
Intellectual 330 points
Other Parts Discussed in Thread: BQ24190

Hello,

     I am presently using the BQ24190 EVM and I've noticed that if I allow my connected battery to run completely empty, then connect a USB charger to the EVM, the charge current limit is ~200mA, and it remains there.  However, if I disconnect the USB charger, then re-connect, the current on the charge to battery increases to ~600mA.  Can anyone tell me why this is?  I am doing nothing else in the process...just a simple disconnect and reconnect of the USB charger.

Thanks,
Joe

  • 0
    TI__Mastermind 29655 points

    Hi Joe,

    Thanks for your patience. Some follow-up questions:

    1. Are you using the BQ24190EVM with the EVM software or are you using the EVM autonomously without I2C communication between PC and BQ24190?

    2. If you are using the EVM software to control the registers of the BQ24190, are you seeing any register values for charge/precharge current changing involuntarily, and if so, what is happening?

    3. Did you program any register values different from the default charging settings for your application? 

    4. What is the VIN of the charging adaptor?

    5. When you mention that the battery is run to completely empty, what voltage are you measuring on the battery?

    I am trying to understand if some built-in software protocol with the BQ24190 is being called when you disconnect/reconnect the USB charger. The default charge current settings are shown below, so perhaps there may be some issues in setting the charge current around the ~3V deep discharge threshold, where the default current limit is 256mA.

     

    Thanks,

    Michael

  • 0 in reply to Michael Lu (Santa Clara)
    Intellectual 330 points

    Michael,

    1. yes.  Originally, we just connected the battery to the EVM and brought up the system.  After having this issue, I have since connected the EVM to the PC to look at the pre-charge registers, any other registers that I thought might have an impact on this issue and be able to adjust them.  I changed the values of the pre-charge registers just to see if it made a difference and it did not.  So I don't think it is specifically due to pre-charge.

    2. I have done reads while running and I don't see register values changing with regard to pre-charge.

    3. Yes, but only after I saw this issue did I start changing register values.  Before then, I just used default settings.

    4. I've used 2 different chargers, one that works and one that creates this low input current issue.  On both, the VIN goes over 5.0V.  However, on the one that doesn't work, it immediately goes to about 1.5V then ramps up to 2.5V over about 1ms, then at 1ms, the voltage immediately rises to over 5V.  On the charger that works properly, the voltage immediately goes to over 5.0V with no intermediate step.  Could this be the heart of the issue?

    5. I use our current development system to run the battery down and have been able to do so to around 3.2V.  I think at one point I had a battery down to 2.8V...both exhibited the issue.  But, again, even if I leave the battery charging, it can get up to 3.6V, 3.7V, 3.8V without every changing out of this low current charge state.  The only thing that changes it is disconnecting and reconnecting.

    Thanks!
    Joe

  • 0 in reply to Michael Lu (Santa Clara)
    Intellectual 330 points

    VIN of non-working charger when applied to empty battery...

     

    VIN of bad charger when re-connected (this is the case where current seems to be correct)...

    VIN of charger that always works properly with empty battery...

     

  • 0 in reply to Joe Rule
    TI__Intellectual 1910 points

    Joe,

    Based on my understand you have two EVMs that behave differently when VBUS is applied. Can you provide the jumper settings on JP1,JP2, and JP6. Also I would need screenshot of the EVM GUI when the EVMs appears to function correctly vs incorrectly.

    It may be fastest to close this case to have a conference call. Can you send your contact to s-wong@ti.com so that we can schedule a time.

    Regards,

    Sam