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Original question:

BQ25504: how to disable the 16sec reset OCV sampling while using the ext Vref MPPT?

BQ25504: Response time for ext Vref in an external MPPT algortihm approach?

M Ouda
Prodigy 130 points
Part Number: BQ25504

Hi,

I'm using an external Vref and built an external MPPT algorithm. 

MPPT algorithm: 1) Set Vref   

2) measure Iin_dc  input current to Vin_dc

3) calculate next Vref (using increment conductance algorithm) 

Question: How fast should I measure the input current after setting a new Vref? what is the response time of the BQ25504 since I set a new Vref to measure a new input current for the next step of the MPPT algorithm? 

Thanks,

Ouda

  • 0
    TI__Genius 10385 points

    Ouda,

    You should be able to measure the input current almost instantly when overdriving Vref. As you have MPPT disabled you should not have to hold off on the order of seconds.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Prodigy 130 points

    Thank you for your answer, Ricardo. In order to implement an external MPPT algorithm (such as increment conductance )

    I  set Vref and measure input current Iin_dc and calculate next Vref ...multiple times (usually in 7-10 iterations)

    I need to reach to the optimal Vref as fast as 300ms, i.e.: I need to set Vref and measure in current just in 25ms or so. 

    Is 25ms enough for the TI chip to settle after setting a new Vref, so I  can measure the current and power and calculate with next Vref ?

    Thanks

    Ouda

  • 0 in reply to M Ouda
    TI__Genius 10385 points

    Ouda,

    I would advise you to program a 100 ms wait time, but you should confirm this on your own set up as we do not warranty this timing in the datasheet. From my observations in the lab today I saw that it was typically in the order of 50 ms. I would double this number to have a safe catch all value, and again verify this in your own tests.

    Thanks,

    Ricardo