Achieving a larger voltage than the battery voltage

[tfoutz99]

Hi! I'm working on a circuit, and I'm trying to figure out a way to output a larger voltage than 3.7 from a lithium battery, and to be able to adjust that voltage when needed. e.g., output 10 V for 2 seconds, then 9 V for 2 seconds.

I looked into a charge pump setup (create a voltage across one capacitor, then another, then connect them in series). In my understanding, this permits setting the voltage to multiples of the source voltage, e.g.

3.7 V (source),
7.4 V (2 identical caps),
11.1 V (3 identical caps)...​

but this voltage cannot be adjusted to, say, 10 V without swapping out capacitors.

I know an opamp can adjust the output voltage, but again it can only bump up the output voltage up to the source voltage. Since it too is powered by the battery, this would be capped out at the source voltage.

Of course, a combination could be performed, where I triple the voltage (11.1 V), and then use an op-amp to adjust that down to 10 V. However, I would like to not have anything in the circuit be higher than what I need.

Is this possible?

(I'm really a novice at circuit design, so please let me know if there is anything I'm completely glossing over!)

 

[yungman]

Look into DC to DC converters or build your own little converter using ICs available from company like LTC etc. You should be able to find adjustable step up converters. Or design your own using those ICs and they have application circuits.

 

[tfoutz99]

Thank you for your reply. That's exactly what I was looking for!