The buck-boost is a popular non-isolated, inverting power stage topology, sometimes called a step-up/down power stage.
Power supply designers choose the buck-boost power stage because the output voltage is inverted from the input voltage, and the output voltage can be either higher or lower than the input voltage.
The converter gets its name from producing an output voltage that can be higher (like a boost power stage) or lower (like a buck power stage) in magnitude than the input voltage.
However, the output voltage is opposite in polarity from the input voltage.
The input current for a buck-boost power stage is discontinuous or pulsating due to the power switch current that pulses from zero to IL every switching cycle.
The output current for a buck-boost power stage is also discontinuous or pulsating.
This is because the output diode only conducts during a portion of the switching cycle.
The output capacitor supplies the entire load current for the rest of the switching cycle.