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BQ25185: BQ25185 has an option Solar Power Input and our Solar Current is about 5mA to 200mA

Mike Wang
Prodigy 30 points
Part Number: BQ25185

Tool/software:

If we use a 5.5V 0.82W Sopar Panel as the input of BQ25185, the solar Current will be 5mA to 200mA.

Could you please calculate how much efficiency BQ25185 converted? Don't see any data from TI when a Solar Input applied.

And we are using a Low Temperature  (-50˚C to 50˚C) 10Ah Battery. Can BQ25185 make such thermal range control?

Thanks!

  • 0
    TI__Mastermind 18005 points

    Hi Mike,

    The charger BQ25185 will try to pull as much current from the input as possible, until that input source falls to either VBAT+330mV or a minimum voltage of 3.6V. With this in mind the expected voltage drop from input to battery will be expected to be 330mV. So for the period during which VIN is battery tracking power in and power out will be:

    Power in = (VBAT+330mV) * (IIN)

    Power out = (VBAT) * (IBAT)

    IIN and IBAT will vary by input quiescent current (0.75 mA) and SYS current load. SYS load is application dependent and doesn't necessarily factor into charging efficiency. Therefore Efficiency should be about  ((VBAT) * (IBAT)) / ((VBAT+330mV) * (IBAT+0.75mA)) 

    VBAT = 3.6 VBAT = 4.2
    IBAT = 5 mA ~79% ~80%
    IBAT = 200mA ~91% ~92%

    For VBAT below 3.6V,  Efficiency = (VBAT) / (3.6V), which can vary significantly.

    Mike Wang said:
    And we are using a Low Temperature  (-50˚C to 50˚C) 10Ah Battery. Can BQ25185 make such thermal range control?

    Do you have an NTC selected for these temperature threshold? The BQ25185 does not typically have TS windows that go so far into negative temperatures but I can see if there's any external compensation that can help.

    Best Regards,

    Juan Ospina