This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25570: Reference design of energy harvesting

Part Number: BQ25570

Hi team,

My customer want to add the function of energy harvesting for their product, including some small energy like RF, vibration.

I find that we have some device for this application but I'm not very familiar with it, could you help to recommend some design?

For their system, Vin is 0-9V no load and 0-4V with load, expected current is greater than 1mA .

Thanks!

Colin

  • Hi Colin,

    Our energy harvesting products utilize our charger's VINDPM control loop, which regulates the charger's input voltage to prevent the charger from pulling too much current from the adapter.  Instead of being a fixed VINDPM voltage, the energy harvesting products periodically sample a high impedance source open circuit voltage and then regulate to a fixed percentage of that voltage.  For example, a solar panel's MPP is typically 80% of VOC.  

    The BQ25570 is a boost only charger so inputs MPP input voltage must be lower than its output voltage.  Its maximum input voltage is around 5.0V and output voltage is 5.5V.  

    What is the expected storage element at the output, LiIon battery? Supercap?

    Regards,
    Jeff 

  • Hi Jeff,

    The storage element at the output is 1 cell Li-Ion battery.

    Best Regards,

    Colin

  • Hi Colin,

    The BQ25570 will only work if its input voltage is below the 4.2V battery regulation voltage.  I suppose we could had a Zener clamp on the input to lower the 9V unloaded rail to less than 4V.  The low 1mA current and boost requirement is difficult for any of our other chargers to achieve.

    Regards,

    Jeff

  • Hi Jeff,

    I have updated to customer, any material could I send to them refer about BQ25570?

    Best Regards,

    Colin

  • Hi Qixiang,

    Unfortunately, I do not have a reference design for a similar application. The main concern when adding the Zener clamp on the input will be the Zener clamp leakage current stealing current from the source.

    Regards,

    Jeff