5

Charge pumps use capacitors and not inductors. https://en.wikipedia.org/wiki/Charge_pump

Boost converters require inductors. https://en.wikipedia.org/wiki/Boost_converter

Both charge pumps and boost converters seem to serve the same purpose. Would charge pumps be preferable given that it does not use inductors? What are the pros and cons of charge pumps versus boost converters as DC-DC converters?

user768421
  • 1,187
  • 6
  • 16
  • 28
  • 1
    well, if you don't like inductors for some reason they are. – Jasen Слава Україні May 22 '16 at 05:15
  • inductors tend to be bulky. Are there occasions when boost converters are preferable? – user768421 May 22 '16 at 05:16
  • I have never used a charge pump IC. I have used boost controllers many times. I have seen charge pumps integrated into IC's when they did not need large amounts of current. For example, maybe they just need to generate a high voltage to turn a high-side NMOS gate on. If the amount of current needed is 100 mA or more, I think you will usually be better off with a boost regulator due to efficiency. – user57037 May 22 '16 at 06:37

3 Answers3

6

Boost converters can be efficient at a continuous range of voltage ratios. Charge pumps work best at fixed ratios. and for ratios other than (approximately) 2:1 or -1:1 they become increasingly complex.

I've got a 2W boost converter (5V to 12V) here that has an inductor about as big as a tic-tac, I've never seen a 2W charge pump.

Jasen Слава Україні
  • 31,874
  • 1
  • 31
  • 65
5

Charge pumps are inherently inefficient when used as voltage converters: charging (or discharging) a capacitor loses some energy. Always. Even with ideal components.

An ideal inductor-based voltage converter can be lossless. An inductor-based current converter has the same problem as a capacitor-based voltage converter.

We mostly work with fixed voltages, so an inductor-based converter is generally preferred.

There are some answers on this site that elaborate more on this, including discussions about the unavoidable loss when charging a capacitor from a fixed voltage.

Wouter van Ooijen
  • 48,407
  • 1
  • 63
  • 136
0

Charge pumps are DC circuits, based on capacitors. As capacitors charge, current flow reduces. Inductors on the other hand, have very low ohmic resistance so high currents can pass through them, hence buck/boost converters for power applications are based on both, capacitors & inductors.

Bigger capacitors in charge pumps can deliver more current, but then so can higher voltage. Smaller inductors can do the same job with less weight & space.

Charge pumps are good for information processing by manipulating voltages and very efficient since they work with low currents eg. arithmetic and clamper circuits. Not good for power applications though, no good for high power DC-DC converters.

Zimba
  • 117
  • 4
  • I don't understand these paragraphs; the subjects aren't connected, or justified. Could you explain better? Also why are several sentences copied from https://electronics.stackexchange.com/a/666310/311631 ? – Tim Williams May 12 '23 at 16:43
  • Boost converters are better than charge pumps, because of inductors making them more efficient and allowing higher power and current. – Zimba May 16 '23 at 15:57