Editing DC-to-DC converter (section)

=== Magnetic===

In these DC-to-DC converters, energy is periodically stored within and released from a [[magnetic field]] in an [[inductor]] or a [[transformer]], typically within a frequency range of 300&nbsp;kHz to 10&nbsp;MHz. By adjusting the [[duty cycle]] of the charging voltage (that is, the ratio of the on/off times), the amount of power transferred to a load can be more easily controlled, though this control can also be applied to the input current, the output current, or to maintain constant power. Transformer-based converters may provide isolation between input and output.  In general, the term ''DC-to-DC converter'' refers to one of these switching converters. These circuits are the heart of a [[switched-mode power supply]]. Many topologies exist. This table shows the most common ones.

{| class="wikitable"
|-
! width="10%" |
! width="45%" | Forward (energy transfers through the magnetic field)
! width="45%" | Flyback (energy is stored in the magnetic field)
|-
! rowspan=3 | No transformer (non-isolated)
| {{unbulleted list
 | [[buck converter|Step-down (buck)]] - The output voltage is lower than the input voltage, and of the same polarity.
 }}
| {{unbulleted list
 | Non-inverting: The output voltage is the same [[electric polarity]] as the input.{{unbulleted list
  | style=margin-left:1.6em;
  | [[boost converter|Step-up (boost)]] - The output voltage is higher than the input voltage.
  | [[SEPIC converter|SEPIC]] - The output voltage can be lower or higher than the input.
  }}
 | Inverting: the output voltage is of the opposite polarity as the input.{{unbulleted list
  | style=margin-left:1.6em;
  | [[buck-boost converter|Inverting (buck-boost)]].
  | [[Ćuk converter|Ćuk]] - Output current is continuous.
  }}
 }}
|-
| colspan=2 align="center" | {{unbulleted list
 | [[buck-boost converter|True buck-boost]] - The output voltage is the same polarity as the input and can be lower or higher.
 }}
|-
| colspan=2 align="center" | {{unbulleted list
 | [[Split-pi|Split-pi (boost-buck)]] - Allows bidirectional voltage conversion with the output voltage the same polarity as the input and can be lower or higher.
 }}
|-
! With transformer (isolatable)
| {{unbulleted list
 | [[Forward converter|Forward]] - 1 or 2 transistor drive.
 | [[Push–pull converter|Push-pull (half bridge)]] - 2 transistors drive.
 | [[H-bridge|Full bridge]] - 4 transistor drive.<ref>{{cite journal|url=https://ieeexplore.ieee.org/document/9265771|title=11kW, 70kHz LLC Converter Design for 98% Efficiency|date=November 2020 |pages=1–8 |doi=10.1109/COMPEL49091.2020.9265771 |s2cid=227278364 |url-access=subscription }}</ref>
 }}
| {{unbulleted list
 | [[Flyback converter|Flyback]] - 1 transistor drive.
 }}
|}

In addition, each topology may be:
; Hard switched: Transistors switch quickly while exposed to both full voltage and full current
; Resonant: An [[LC circuit]] shapes the voltage across the transistor and current through it so that the transistor switches when either the voltage or the current is zero

Magnetic DC-to-DC converters may be operated in two modes, according to the current in its main magnetic component (inductor or transformer):
; Continuous: The current fluctuates but never goes down to zero
; Discontinuous: The current fluctuates during the cycle, going down to zero at or before the end of each cycle
A converter may be designed to operate in continuous mode at high power, and in discontinuous mode at low power.

The [[H-Bridge|half bridge]] and [[flyback converter|flyback]] topologies are similar in that energy stored in the magnetic core needs to be dissipated so that the core does not saturate. Power transmission in a flyback circuit is limited by the amount of energy that can be stored in the core, while forward circuits are usually limited by the I/V characteristics of the switches.

Although [[MOSFET]] switches can tolerate simultaneous full current and voltage (although thermal stress and [[electromigration]] can shorten the [[MTBF]]), bipolar switches generally can't so require the use of a [[snubber]] (or two).

High-current systems often use multiphase converters, also called interleaved converters.<ref>
Damian Giaouris et al.
[http://onlinelibrary.wiley.com/doi/10.1002/cta.1906/abstract "Foldings and grazings of tori in current controlled interleaved boost converters"].
{{doi | 10.1002/cta.1906}}.
</ref><ref>
Ron Crews and Kim Nielson.
[http://powerelectronics.com/power-management/interleaving-good-boost-converters-too "Interleaving is Good for Boost Converters, Too"].
2008.
</ref><ref>
Keith Billings.
[http://powerelectronics.com/content/advantages-interleaving-converters "Advantages of Interleaving Converters"].
2003.
</ref>
Multiphase regulators can have better ripple and better response times than single-phase regulators.<ref>
John Gallagher
[http://powerelectronics.com/passive-components/coupled-inductors-improve-multiphase-buck-efficiency "Coupled Inductors Improve Multiphase Buck Efficiency"].
2006.
</ref>

Many laptop and desktop [[motherboard]]s include interleaved buck regulators, sometimes as a [[voltage regulator module]].<ref>
Juliana Gjanci.
[http://www.ece.uic.edu/~masud/Juliana_MS_THESIS_final.pdf "On-Chip Voltage Regulation for Power Management inSystem-on-Chip"] {{webarchive|url=https://web.archive.org/web/20121119013307/http://www.ece.uic.edu/~masud/Juliana_MS_THESIS_final.pdf |date=2012-11-19 }}.
2006.
p. 22-23.
</ref>