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BQ25570: MPPT

Manel Gasulla
Prodigy 115 points
Other Parts Discussed in Thread: BQ25570, BQ25504

I've seen in section 7.1 of the datasheet that an external voltage can be used to set the MPP point. I suppose you have to introduce the external voltage directly in the VREF_SAMP pin. In this case, can the periodic sampling be disabled? I've seen that this is possible with the BQ25504 IC by tying the VOC_SAMP pin to VSTOR but if you do this for the BQ25570 IC, it is specified that the MPP voltage will be 80 % of the input open circuit voltage. And a I've found no indication of how disabling the sampling process, if possible.

  • 0
    TI__Mastermind 19430 points
    The MPPT sampling cannot be disabled in the bq25570.
  • 0 in reply to Jing Zou
    Prodigy 115 points
    ok, thanks. But anyway, can an external voltage can be used to override the sampled voltage? Does the IC has some drawback or improper operation in this case?
    On the other hand, I've seen than in the corresponding evaluation board there are 3 different reference voltages to choose from (50 %, 80 % and 75%). Is it possible to choose another factor using external resistors selected by me? I have seen no (easy) way to connect user-selected resistors to the board. It seems there are no access pins for this option, isn't? I think, the same happens with the evaluation board of the BQ25504 IC.
  • 0 in reply to Manel Gasulla
    TI__Guru*** 143850 points
    You can provide a external voltage directly to VREF_SAMP via the non-GND side of JP5. Or you can use external resistor divider from VIN_DC to VOC_SAMP. The EVM has these resistors installed (R3, R4 and R5) which need to placed into circuit with jumper JP1 (and no shunt on JP4).