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BQ24650EVM-639: DC Supply as Vin

Marianne Fatima Valenzeuela
Prodigy 50 points
Part Number: BQ24650EVM-639
Other Parts Discussed in Thread: BQ24650

I am trying to utilize the EVM solely for powering the load and  charging a battery. I just want to know if some of my 'understandings' on how the module work is right.

1. Vout will supply to Vsys when Vin is not supplied.

2. Vout will be ~12.6V and 2A for Vin higher than 17.8V.

3. A drained battery will just be able to charge if it reaches the VLow through pre-charging current (200mA) for 30 minutes.

Also, is this module suitable for a 12V/8A LiFePO4 battery? Especially that the charging voltage for it is 3.6V/cell.

  • 0
    TI__Mastermind 40845 points

    Hello,

    1. Vout will supply to VSYS when Vin is not supplied.

    2. The maximum charging voltage is 12.6 V and the charge current will be 2 A. This does not mean that the Vout voltage is always 12.6 V.

    3. A drained battery will charge if it reaches Vlowv before 30 minutes. Otherwise the charger will turn off.

    You will have to change the inductor and sense resistor if you want to charge at more than 2 A.

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.

  • 0 in reply to Michael Emanuel35
    Prodigy 50 points

    For number 2, I have observed that it only reaches 12.6 V for input more than 17.8, anything below that will have a Vout of 0.7 only. Is that right?

    3, does this mean I have to really remove and change the built-in L1 and R6? 

    May I ask again about:  is this module suitable for a 12V/8A LiFePO4 battery? Especially that the charging voltage for it is 3.6V/cell.

  • +1 in reply to Marianne Fatima Valenzeuela
    TI__Mastermind 40845 points

    Hello,

    You may be putting the part into input regulation. The EVM will automatically reduce charge current if the input is less 17.8 V. The below excerpt is from the datasheet. If you want to enable lower input voltages adjust the MPPSET divider accordingly.

    "If the solar panel or other input source cannot provide the total power of the system and BQ24650 charger, the input voltage drops. When the voltage sensed on the MPPSET pin drops below 1.2 V, the charger maintains the input voltage by reducing the charge current. If the MPPSET pin voltage is forced below 1.2 V, the BQ24650 stays in the input voltage regulation loop while the output current is zero. The STAT1 pin is LOW and STAT2 pin is HIGH."

    Please refer to the below table from the EVM user guide. Higher charge current will require a different inductor and resistor. As you can see the max charge voltage is 26 V and the max charge current is 8 A for this EVM.

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.