2
\$\begingroup\$

I'm not really sure why an inverting buck-boost might be disadvantageous compared to a non-inverting converter. If the load has a particular polarity, then can't you just connect it backwards to achieve the same effect?

\$\endgroup\$
  • \$\begingroup\$ I'm guessing that there are practical drawbacks with level-shifting the signals signals between the non-inverted part of the circuit (things like battery management would probably live there), and the inverted part of the circuit. (+1 for the question, by the way.) \$\endgroup\$ – Nick Alexeev Apr 26 '15 at 22:28
3
\$\begingroup\$

A inverting switch-mode converter actually is the most simple topology if the magnitude of the output voltage might be lower or higher than manigtude of the input voltage (typical example: making 3.3V from the 3.0-4.2V of a Li-Ion battery).

There are two disadvantages of this topology you call "inverting buck-boost", though. The first is that electric engineers are used to reference everything to a fixed "ground" potential. In case of an isolated battery, that's not a problem, but often this "ground" potential is actually mains earth. You can't generate a positive voltage referenced to mains earth form another positive voltage referenced to mains earth, using the inverting topology, hence the name. The other disadvanted is that the inverting topology is more demanding on the inductor if input and output voltage are similar (this typically is the case on buck/boost regulators). In both buck and boost mode, some energy is transferred from the input directly into the output, and only a part of the energy on the output was temporarily stored as magnetic field. In the inverting topology, the whole energy at the output was intermediately stored in the core.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.