LTC3130 minimum on time solar power supercapacitor

My project is basically the same as the first example on page 30 of the datasheet here. It has PV solar panel input with MPPT and RUN pin control and outputs to supercapacitors, in my case a series of 5 of them. But the output voltage of 15V is a bit too much. Sometimes it can give ~14V, sometimes not.

How can I calculate a reliable output voltage? Especially considering I might only have a trickle of current as power at the input. Maybe I can tweak the inductor or other parts to squeeze out more?

In some of my practice implementations, I've seen the "ambitious" design work great. The PV gives ~4v and it slowly charges up the supercaps even in low power times at the end of the day, like dusk. Other times I connect it to a power supply at 5.5v and it doesn't charge the supercapacitors at all, the output is stuck at ~3v.

  • 0
    •  Analog Employees 
    on May 28, 2021 7:56 PM


    I have a few questions here. Can you give more details about the application circuit and design requirements. 

    If the input source is a weak source, the  input capacitance should be selected such that it should be able to get Vin charged to rise the UVLO.(pg 26 of the datasheet)  Also the design will depend on its operating point of the PV panel and the load conditions. 

    If you share your application circuit details  and the desired operating point I can look into it the design and suggest you further.