Switch Mode Power Supplies

A Switch Mode Power Supply (SMPS) is a type of power supply unit that utilises switching regulator technology.
They are used to convert electrical power efficiently, resonating with high frequency.
SMPS replaces heavy, bulky power supply components with small, lightweight ones, such as transistors.
SMPS designs can be broken down into several topologies: buck, boost, buck-boost, and flyback are common examples.

SMPS use high frequency pulse width modulation (PWM) to adjust the output voltage.
They work by switching a power transistor between saturation (full-on) and cut off (completely off) with varying duty cycle.
This fast switching minimises the energy wasted as heat.
The duty cycle of the PWM adjusts the output voltage of the SMPS.

SMPS are highly efficient due to their high frequency operation and use of the power transistor as a switch.
They can provide multiple output voltages simultaneously in the same device.
They are exceptionally light because they replace heavy line-frequency transformers with lighter high-frequency versions.
SMPS can work over a wide range of input voltages without adjustment, making them practical for international equipment.

Designing SMPS circuits requires careful consideration of switching times to prevent energy being wasted as heat, reducing efficiency.
Pulse Width Modulation (PWM) circuitry forms a core part of the design, controlling the duty cycle of the switching transistor.
An SMPS design may include an electrical component called a rectifier, which converts AC to DC, and a filter to smooth the rectified signal.
To avoid noise issues, careful consideration of the placement and shielding of high-frequency components is critical.

SMPS are widely used in household applications such as televisions, computers and battery chargers.
Due to their high-efficiency and lightweight design, they are popular for use in aeronautical and automotive electronics where weight is a critical consideration.
SMPS provide stable operation over a range of input voltages, making them suitable for use in electrical devices deployed throughout the globe.