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BQ25890: Series - Standalone Mode , No I2C

Glen Rayward1
Prodigy 50 points
Part Number: BQ25890
Other Parts Discussed in Thread: BQ25895, BQ25616

Hi,

How is Standalone mode achieved when the datasheet keeps referring to I2C?

We want very similar functionality, but cannot see how to achieve it without attaching to I2C.

Is it possible? what functionality will we be missing out on?

For reference or suggesting of alternate parts our requirements are:

Adapter Plug (Dumb 2.4A or Samsung Fast Charge) -----> [Our Device] ----> Samsung Phone/Tablet (Most likely USB-C) To be Charged by Adapter AND/OR Battery

                                                 ^---- 3000mA Li-ion Battery to be charged by Adaper and to Charge Phone when no adapter plugged in

Cheers

-Glen

  • 0
    Prodigy 50 points

    Sorry, I realize this part doesn't have the Phone Boost charge functionality, Please rename BQ25890 to BQ25895

  • 0 in reply to Glen Rayward1
    TI__Guru**** 166506 points

    Hi Glen,

    BQ25895 operates in the default mode (ICHARGE=2A, VBATREG=4.2V, etc) without I2C when power is applied at VBUS.  If OTG pin is high, it will automatically go to OTG mode when VBUS voltage drops below the UVLO threshold, providing power to PMID.  Without I2C you will be unable to change charge current, another of the DPM loops, monitor the status/error registers, etc.

    We do not have a standalone version of BQ25895.  The closest fit is 3-A charge, 1.2-A OTG boost mode BQ25616. It provides OTG back to VBUS not PMID. 

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff,

    The BQ25616 looks OK, are you saying to connect the phone through a 5V Boost converter from the SYSTEM line?

    The BQ25895 page shows Control Interface as I2C and Standalone (RC-Settable)   So it can be used in Standalone or is this not true?

    Cheers

    -Glen

  • 0 in reply to Glen Rayward1
    TI__Guru**** 166506 points

    Hi Glen,

    Both devices' OTG mode works by boosting the battery voltage back to PMID and then on to VBUS for the BQ25616.   The BQ25895 OTG stopping at PMID was intended to be used in power bank applications.  The phone or other device to be charged could then be connected to a separate port (PMID) from VBUS.  Alternatively, you could run a boost converter from SYS that provides 5V. 

    Regarding BQ25895 standalone mode, the BQ25895 can operate without I2C. The only RC-settable function is input current limit with the ILIM pin.  If you have I2C available at least at power up, the host can disable the watchdog timer (that resets all registers to defaults when expired) and then configure different settings than default (ICHARGE=2A, VBATREG=4.2V, etc.). 

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff,

    Thanks, so for BQ25616 connect the Phone power directly to the PMID or the VBUS pin? What is the voltage range of the PMID pin, there isn't much info in the datasheet regarding this pin.

    By the way what does PMID stand for?

    Cheers

    -Glen

  • 0 in reply to Glen Rayward1
    TI__Guru**** 166506 points

    Hi Glen,

    PMID has the same voltage rating as VBUS.  PMID stands for power middle but is really the input to the buck converter / output of the boost converter. 

    Regards,

    Jeff