DC Current Booster

[Raven Luni]

Greetings,

I cant quite get my head round this at the moment but I was wondering if there was an easy and efficient way (without using oscillators etc) to step down a small DC voltage in order to get more current.

The reason I ask is because I have some 1F capacitors I was thinking of using for memory backup. They're rated at 5.5V but the memory (Alliance AS6C1008 SRAM) has a minimum retention voltage of 1.5V. So if I could charge the capacitors at 5V but only take say 2V for the memory without wasting current in resistors and other components. is this doable?

 

[BobK]

What you need is a switch mode regulator. They can reduce voltage with about 80 to 90% efficiency. If you want to know the theoy, look up buck converter.

Bob

 

[Laplace]

It would be interesting to investigate using a charge pump to lower the voltage. Charge pumps are normally used to double, triple, etc., a smaller voltage. This approach will not increase current but it will conserve charge, which seems to be your goal. The approach is to use the 5V capacitor to charge another capacitor to 2V through a switch where the switch is controlled by a comparator. The comparator uses a 2V reference to compare the voltage on the 2V capacitor. Of course the comparator and voltage reference would need to be micro-power components to avoid wasting more power than the charge pump is saving, and be capable of operation below 2V in order to get the last bit of charge from the source capacitor.

 

[Raven Luni]

Most interesting. I ended up reading a fair bit about multiphase converters and their use for CPU supplies. I now have more to think about than just memory backup. Still - the fun is in the learning and I'm having great fun