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BQ25570, MPP resistor values

Volker Skwarek
Prodigy 60 points

In the data sheet chapter 8.1.2.1 says, no MPP resistors are required for setting the correct 80% MPP for solar cells.

Comparing the data sheet (fig. 24) with the design help excel tool, this should result in ROC2 = infty, ROC1 = 0. But this does not lead to a correct MPP-voltage of about 80%.

Where is the mistake?

  • 0
    TI__Guru**** 166896 points
    Connect VOSAMP pin to VSTOR to sample at 80% of input source open circuit voltage. Connect to GND for 50% or connect to the mid-point of external resistor divider between VIN_DC and GND.
  • 0 in reply to Jeff F
    Prodigy 60 points

    Yes, this mainly answers my question and is what I have done.

    I just want to indicate that your excel-calculation tool offers for an MPP at 80% VIN dedicated resistors as shown in the picture. That is at least confusing. If there are open (some) questions for users between inconsistencies between data sheets, application notes and calculation tools, this here could be one more...