LAZAR's POWER ELECTRONICS GUIDE

SMPS SWITCHING POWER SUPPLY DESIGN BASICS

The electric energy is not normally used in the form in which it was produced or distributed. Practically all electronic systems require some form of energy conversion. A device that transfers electric energy from a given source to a given load using electronic circuits is referred to as power supply unit (PSU). Of course, it does not really supply power, it just converts it, so "converter" is a more accurate term for such a device. A typical application of a power supply is to convert utility AC voltage into a set of regulated DC voltages required for electronic equipment.
Nowadays most PSUs are of SMPS type, which is the main subject of this site.

WHAT IS IT?

SMPS stands for switched mode power supply. It is an electronic device in which energy conversion and regulation is provided by power semiconductors that are continuously switching with high frequency between "on" and "off" states. An output parameter (usually output voltage) is controlled by varying duty cycle, frequency or a phase shift of these transitions.

HOW DOES IT WORK?

The energy flow in any PSU is controlled by power semiconductors. However, in different systems they can operate in different modes. In legacy systems they worked in linear mode and excessive power dissipated in a series transistor. When a semiconductor operates in switching mode, it can control energy flow with low losses: when a switch is "on", it has low voltage drop and will pass any current imposed on it; when it is "off", it blocks the flow of current. As the result, in such an electronic device the power dissipation which is the product of voltage and current, can be relatively low in both states. That's why switch mode PSUs offer greater efficiency compared with linear ones. Such units are also smaller in size and lighter in weight due to the reduced size of passive components and lower heat generation. The industry trend toward miniaturization, advancements in semiconductor technology, as well as various energy efficiency regulations have made "switcher" the dominant type of PSU across practically the full spectrum of applications. Most PSU manufactured today for AC input applications also include another conversion stage- a PFC front end.

In general, SMPS converters can be classified into four types according to the form of input and output voltages: AC to DC (also called off-line DC power supply), DC to DC (voltage or current converter), AC to AC (frequency changer or cycloconverter), and DC to AC (inverter).

The field of engineering that deals with the design and analysis of power conversion circuits and devices is called power electronics, although power supply design is a true cross-disciplinary task. It involves the circuit, magnetics, thermal management, control and compliance issues. This site is SMPS/power electronics information guide. Here you will find a tutorial, tools, reviews, schematics, and other free online resources on all aspects of switching power supply design and selection, information on other energy conversion devices, as well as basic electrical engineering reference and electronic formulas.




POWER ELECTRONICS / SMPS DESIGN- THEORY & TUTORIALS
TI (Unitrode) seminar books online
Power supply design tutorial - basic concepts and operation
Glossary of energy conversion and power electronics technology terms

FREE SIMULATION SOFTWARE AND CALCULATORS Find open source circuit simulation programs, working demos of analog and mixed-signal simulators, and other engineering software & calculators
Quick online quiz- how well do you know power supply safety

PSU TOPOLOGIES: APPLICATION NOTES, GUIDES, SCHEMATICS
Switching mode converter topology selection
A review of standard computer PSU connectors and pinouts
The basics of switched mode regulators, design guides, SMPS circuit diagrams, and other design resources

PCB DESIGN OF ELECTRONIC CIRCUITS
Layout guidelines for printed circuit board;
Trace spacing for voltages;
Trace width calculator per IPC-2152;
Guidelines, calculators, and other PCB design resources.

TRANSFORMER AND INDUCTOR- THEORY & CALCULATIONS
Magnetic unit conversion: table, formulas and calculator;
Power transformer and inductor design: formulas, software, and other tools and guides.

BACKUP POWER DEVICES
Standby generators - reviews and comparison;
Solar power fundamentals;
UPS guide and review.

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