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BQ25886: BQ25886RGER

Ali Khan
Intellectual 910 points
Part Number: BQ25886
Other Parts Discussed in Thread: BQ25887

Tool/software:

Hi,

I have few questions regarding BQ25886RGER.

  1. What will be the SYS voltages if single cell lipo max voltages are 4.2V i.e. Total 8.4V
  2. Is SYS voltages are regulated or simply BAT voltages?
  3. There are two pin name for pin1 on the datasheet. Which one is correct?

  1. I want to use this charger in standalone mode. Can i leave pins 24,1,5, and 3 NC?
  2. I don't have battery thermistor neither i want to use any. Can i leave NC this pin
  • 0
    TI__Mastermind 34355 points

    Hello,

    1. The system voltage is separated from battery via the voltage drop from the BATFET. Also, from the datasheet "When the battery charging is disabled and VBAT is above minimum system voltage setting or charging is terminated, the system is always regulated at typically 50mV above battery voltage."

    2. From the datasheet, "When the battery is below minimum system voltage setting, the BATFET operates in linear mode (LDO mode), and the system is typically 200 mV above the minimum system voltage setting."

    3. Pin 1 is indeed D-. We will fix this in our next datasheet revision.

    4. Please short D+/D- and adjust ILIM accordingly. If D+/D- are float, an unknown adapter could be detected and there may be input current limit lower than expected. If not intending to use OTG, pull OTG low. If you always want charge enabled, pull /CE low.

    5. Please bias TS between REGN and GND between 2 10k Ohm resistors (one pulled to REGN and TS and one pulled to TS and GND).

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Intellectual 910 points

    Hi
    5: For TS, Can i use the same configuration?

    4: What you mean short D+/D-? Short to Gnd ?

    5: Is this IC maintain balancing the charge across both batteries? I am using two lipo cell connected in series i.e. 4.2V single cell(total 8.4V max)

    Thanks

  • 0 in reply to Ali Khan
    TI__Mastermind 34355 points

    Hi,

    The TS path is only fine if a thermistor is attached to TS in parallel.

    Short D+ to D-.

    There is no cell balancing for the BQ25886. The BQ25887 has it however.

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Intellectual 910 points

    Are they pin compatible and design?
    Can i simply replace the IC?

    If i use BQ25886, what possible issues i can face in charging 2S battery?
    What protocols are there for it to work without damaging battery?

    Thanks

  • 0 in reply to Ali Khan
    Intellectual 910 points

    Plz, check the schematic if there is any issue.
    Thanks

  • 0 in reply to Ali Khan
    TI__Mastermind 34355 points

    Hello,

    They are not pin to pin compatible, so you cannot simply replace the IC.

    This part is fairly easy to use, the only challenge with BQ25886 is making sure the cells are balanced. If used as directed in datasheet the device should function safely. Please check out the following battery fundamentals to better understand battery chargers: Videos | TI.com

    Schematic Review:

    1. Confirm 8.4 V Battery Voltage Regulation

    2. Confirm 1.5 A Charge Current Regulation

    3. ILIM is KILIM/RILIM. This is set incorrectly to 1110A*Ohm / 383000Ohm or 2.9 mA. Please adjust the resistor here.

    Regards,

    Mike Emanuel