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BQ25505: Energy Harvesting PMIC selection/ design

SmartEnrg
Expert 1165 points
Part Number: BQ25505
Other Parts Discussed in Thread: BQ25570

Hi,

I am looking to design energy harvesting capable power supply for a series of wireless devices - 
some TI-CC1352, others based on cellular/ GPS embedded IoT module.

Typical current draw - at 3~3.3V, 20-80 mA; with peak/ short burst current in 335-535 mA range.

My plan is to build upon BQ25505's ability to switch between: primary non'rechargeable source, 
and augment/ supplement that with charge accumulated from a harvested source (TEG or PV).

Couple of questions in regards to this use-case: 
1) Couldn't locate how much max current BQ25505 can deliver. Will BQ25505 support this use-
    case above? If not: 
    a) Is there an alternate part you would like to recommend? Looked at 25504, 25570 already.
    b) Will augmenting BQ25505 with an external FET and/or reservoir cap to deliver high surge 
        current do the trick?

2) Is there a lower cost but drop-in footprint regulator from TI that I could BOM sub for my non-
    harvesting applications? Such that - on a same footprint as BQ25505, I could drop standard 
    regulator?

Please advise. Will greatly appreciate your timely attention and help.

Thanks,
SE

  • 0
    TI__Genius 10385 points

    SE,

    1. The cycle by cycle current limit of the charger is 230 mA. This would be the maximum output you could get from the boost converter.

    a) I would suggest bq25570 because of its integrated buck converter to supply your 3.3V rail and the boost output would charge your rechargeable battery, but the buck output is limited to 110 mA peak current.

    b) This solution could work to handle the peak current draw and is mentioned in section 8.2.1 of the datasheet.

    2. Unfortunately, we do not offer any regulators in the RGT package that you could drop in.

    I also suggest looking at the design tool in the product folder to help you size an appropriate PV panel based on your system requirements.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    TI__Genius 10385 points

    SE,

     

    I have not heard back from you in a while. Please let us know if you have any further questions, otherwise I will be closing this thread.

     

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Expert 1165 points

    Hi Ricardo,

    Thanks for the pointer to "section 8.2.1 of the datasheet" - that approach look promising, exploring that further.

    Will let you know if there are any followup questions. In the mean time, closing this as resolved Thanks again.

    Best,
    SE