So let's say I have a circuit that requires 2 Volts DC exactly as the source, but my power supply can be from 1 Volt to 12 Volts DC.

It would be easy to step down the voltage with a linear voltage regulator if the supply voltage was higher than what is needed for the circuit.

However, I can't seem to find any ICs that do both. It seems like no voltage regulators step up the voltage while stepping down the current into the circuit... So I'm wondering if this is even possible.

The load is a huge capacitor that will draw as much current as possible due to low series resistance! I don't care the rate at which the capacitor charges, as long as the volts don't exceed the maximum rating. 1.5 Volts will be minimum, 12 will be maximum. The capacitor is rated for 2.7 Volts, so storing energy at 2V seems pretty good to me. But in the source is 1.5 Volts, that's a lot of energy that is unable to be stored, so I figured id step it up to 2V somehow.

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    \$\begingroup\$ You need a switching converter. Search for non-inverting buck-boost. Not sure what you mean by "It seems like no voltage regulators step up the voltage while stepping down the current into the circuit" Power out = power in - losses. \$\endgroup\$ – John D Feb 3 '17 at 18:11
  • \$\begingroup\$ Also, the max current that the regulated source puts out will be important if it's not large enough to meet the requirements of the load. \$\endgroup\$ – John D Feb 3 '17 at 18:18
  • \$\begingroup\$ I'm not sure what you mean by "the amps are allowed to vary greatly"? If the load needs more amps than the source can provide then the voltage will droop below the regulated set point. The load current needs to be clearly defined to regulate properly. \$\endgroup\$ – vini_i Feb 3 '17 at 18:18
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    \$\begingroup\$ The term you are looking for is "buck-boost converter". However, a 1 V minimum input could be a problem. Are those actual figures or just speculation? \$\endgroup\$ – Andrew Morton Feb 3 '17 at 18:18
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    \$\begingroup\$ @AndrewMorton is absolutely correct, a 1V minimum input buck-boost will be difficult to find, though there are boost converters that can operate that low. You may need a hybrid approach.... \$\endgroup\$ – John D Feb 3 '17 at 18:29

The linear regulator won't do your work, like you say. Buck-boost is needed.

Sure you can boost up and then buck down. There are simple single-switch topologies that do this in one stage. Zeta, Ćuk, Sepic, or buckboost could work for you. The Ćuk and buckboost give a negative output voltage in their standard form. If this is no good then it narrows it down to Zeta or Sepic. Sepic has low-side drive which makes things simpler but at your low input voltage this is not too important.

There are lots of chips that will do this. These circuits are popular in omnivorous Leds.

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