How to charge a supercapacitor FAST?

[lxlxlx]

It's a design problem and the source is given. I only need to charge the caps to around 3v. It will be used to power something else later.

 

[MikeMl]

To create a switching power supply that behaves like the magic current source I used in the LTSpice simulation, look into using a switcher IC, but instead of setting it up to regulate the output voltage (normal), take the feedback from the input side, and set up the feedback loop so that it tries to maintain a constant 2.5V at it's input. Wouldn't that do it?

 

[lxlxlx]

instead of doing the SMPS, how about to connect a voltage follower to the source circuit and then charge the caps from the output of the voltage follower? Doing this basically eliminates the internal resistance of the source, right?

 

[MikeMl]

But you will be taking the energy to charge the super cap from a auxiliary power source. Is that allowed???

 

[lxlxlx]

Can I power the voltage follower circuit with the original source?

 

[Mr RB]

(repeating because it was not answered)

Do you seriously want a circuit to run from 2.5v 21mA and charge a cap to 5.4v? How much complexity? How efficient? And what is the voltage source and why those exact limitations on the input source? What is the whole lot going to do?

 

[lxlxlx]

I did answer it...No, I only need it to be charged to around 3V. This is a design problem and the source circuit is given and can't be changed. The supercaps will then power something else..