A switching regulator utilizes a the mechanism of pulsing a switch (turns on and off) to control the output voltage. See below figures regarding switch on and off actions in the step-down (buck) switching regulator configurations:
The magnitude of the output voltage depends on the duty cycle of the switch. Transistors are commonly used as the switch element.
The figure below is an example of using an op-amp as the feedback amplifier in a switching regulator. The control circuit uses the error voltage captured by the op-amp to determine the duty cycle of the switch. If the output voltage falls, the duty cycle increases, bringing the output back to its desired value, and vice versa.
The trade-offs between switching and linear regulators can be summarized in the table below:
MCP16301 30V Buck Switching Regulator
Microchip offers a wide range of switching regulators in many applications. For example, Microchip's MCP16301 is a 30 V input, (step-down) buck switching regulator with 600 mA output capability. The MCP16301 features a wide input voltage range, from 4 V to 30 V, an output voltage range from 2 V to 15 V, and provides up to 95 % efficiency. The MCP16301 is ideal for applications in the industrial, telecommunications, consumer and automotive markets; such as set-top boxes, LED lighting, HVAC systems and power meters.
Below is a sample circuit block diagram using the MCP16301: