Buckboost

Buck-boost refers to a class of DC-DC converter topologies that can regulate an output voltage to be higher or lower than the input. The most common form, the buck-boost converter, is an inverting topology that produces a negative output voltage relative to ground. There are also non-inverting buck-boost variants that provide a positive output without polarity inversion, using different network arrangements such as SEPIC, Cuk, or multi-switch configurations.

Most buck-boost converters share a basic operating principle. A switch, inductor, diode, and capacitor are arranged so that when the switch is on, energy is stored in the inductor from the input; when the switch turns off, the inductor releases energy to the output through the diode or a synchronous switch. The output voltage is set by the duty cycle of the control signal and the topology, allowing the converter to step the voltage up or down as needed.

Topologies range from a simple single-inductor, single-switch inverting buck-boost to non-inverting variants that use additional switches or coupled inductors. Non-inverting buck-boost implementations, such as SEPIC or Cuk-based designs, preserve the output polarity while still providing wide input-to-output regulation. Modern implementations often integrate control circuitry and protection features on the same chip.

Applications include battery-powered devices, automotive systems, solar or wind energy harvesters, and portable power supplies, where input voltages can lie below or above the desired output. Key considerations in design are control loop stability, efficiency, thermal management, EMI, and protection against short circuits or reverse polarity.