A switched-mode power supply (SMPS) is an electronics power supply which uses energy storage components (such as inductors and capacitors) and semiconductor-based switches (e.g., MOSFET, SCR, diode), which are switched on and off at a specific exchanging recurrence (usually at high frequencies) in order to achieve stable output voltage and current with minimal distortion. Due to its many advantages such as high efficiency, small size and light weight, SMPS has replaced traditional linear regulators in most of the power supply applications.

There are different classifications of SMPS, for example:
a.Based on Input & Output voltage: AC-to-DC (Rectifier), DC-to-DC (Chopper), DC-to-AC (Inverter) or AC-to-AC (Cycloconverter)
b.Based on Output Characteristics: Constant Voltage (CV) or Constant Current (CC)
c.Based on Existence of Electrical Barrier between Input and Output Ports: Isolated or Non-isolated

A typical SMPS for AC to DC conversion is composed of EMI (electromagnetic interference) filtering circuit, bridge rectifier, PFC (power factor correction) circuit, DC/DC converter (usually comprised of transformer, high voltage switches at primary side, low voltage switches at secondary side for synchronous rectification, feedback circuit and controller IC), as well as protection circuits such as anti-surge circuit at primary side and OVP at secondary side.

Figure 1. Circuit Diagram of a typical AC/DC SMPS

JJM offers wide portfolio of MOSFETs, power diodes, opto-couplers, as well as surge protection devices such as MOV, TVS, and ESD diodes for implementing an efficient, robust and reliable switched-mode power supply.