Operation of a Switch Mode Power Supply

How a Switch Mode Power Supply Works? What is the operation of a switch mode power supply? A switch mode power supply works by continuously switching on and off a semiconductor switch. This semiconductor switch is can be a MOSFET or a BJT. The former is more popular than the latter. When the switch turns off, there is no current

Important MOSFET Design Parameter

How to Select a MOSFET for Power Electronics

These are the important things to consider on how to select a MOSFET for power electronics. These parameters when considered during the development stage, you can ensure a product with a very high reliability. 17 Key Items to Consider on How to Select a MOSFET for Power Electronics 1. Gate to Source Threshold Voltage (VGSth) Let us start this tutorial


Switching Power Supply Operation Principle and Design

Switching power supply operation is very different to that of linear power supply. Despite of its complexity, higher bill of material cost and higher parts count, switch mode power supply is still the preferred power supply topology in the market nowadays. The main reason is higher efficiency and higher power density. Higher efficiency simply means that only a small portion


How Switch Mode Power Supply Regulates its Output

In linear power supply design output regulation is not a question because it is easily done by the linear regulator inserted before the load. Nowadays linear power supply is not anymore widely used. What is drawing more attention now is the switch mode power supply. How switch mode power supply regulates its output is different from what linear regulator does.


Fuse Operation and Principle

In this article I will discuss Fuse Operation and Principle. A fuse is a simple electrical part which consists of a wire and terminals on each end. It is plainly a passive device which protects the circuit in the event of a large current. When this happens, the fuse element will open and the circuit will become discontinuous. Fuse operation

MOSFET and BJT Comparisson

MOSFET Advantages Over BJT in Switching Converters

Way back several years ago, power supply designers and engineers are continuously searching for innovation. Long time ago what is available is only the linear type power supply. A linear power supply will consume a lot of power in order to provide regulation. This huge power consumption sacrifices the efficiency of the power supply. Try to imagine if you are

MOSFET efficiency factors

MOSFET Efficiency Factors for Switching Converters

We will discuss here the three main contributors of power losses of the MOSFET when used in switching converter or switch mode power supply. The main MOSFET efficiency factors are drain to source on state resistance, gate charge and the equivalent output capacitance.  Drain to source on state resistance or simply RDSon has a positive temperature coefficient (increases with temperature


Transformer Design and Selection QR Flyback

Several factors to consider in order to perfectly arrived a good Quasi Resonant Flyback transformer design. It needs to consider the input voltage and the allowed level of the switch drain to source (or collector to emitter) voltage of the switch to define the level of the reflected voltage (Vref). It is also required to know the level of the


How to Select a Transformer

Before going to the discussion on how to select a transformer, let us cover first some of the transformer basic fundamentals. Transformer is could be a low frequency like those used in 50Hz or 60Hz line. Transformer is could be a high frequency one like those used in switching mode power supplies. Transformer will transfer power from the primary to