SMPS SWITCHING POWER SUPPLY CIRCUIT DESIGN:

TUTORIALS, SCHEMATICS, THEORY, BASIC VOLTAGE
REGULATOR TOPOLOGIES, AND OTHER ONLINE RESOURCES

The industry drive towards smaller, lighter and more efficient electronics has led to the development of switching-mode power conversion technology. Switching power supplies (SMPS) incorporate power handling electronic components which are continuously switching on and off with high frequency. These electronic switches effectively connect and disconnect energy storage inductor(s) to and from the input source or the output. By varying duty cycle, frequency or phase shift of these commutations, an output parameter (such as output voltage) is controlled. Output filters are "averaging" energy transfer rate and assure continuous power flow into the load.

The typical frequency range of an offline SMPS is from 50 kHz to 500 kHz. DC-DC converters with low voltage input operate up to several MHz. The high operating frequency results in the smaller size of switch-mode power supplies since generally the size of power transformers, inductors and filter capacitors is inversely proportional to the frequency. Switch mode operation also reduces energy losses - when a switch is "off," its current is near zero; when it is "on," the voltage across it is low. On the other hand, this mode of operation introduces the losses that occur during the transitions and which increase with operating frequency. It also introduces additional electrical noise (EMI) whose acceptable limits vary with the frequency. The switcher's frequency is normally selected based on size, efficiency, cost and EMI considerations. Realizing the switcher's advantages requires the selection of components that can operate efficiently at the necessary frequencies.

There are about a dozen basic topologies used in practical power design. The best topology for a given application is selected based on specific requirements for the power supply (including cost and time factors), although this selection is often influenced by the personal experience of the designer.

Here you will find theory, SMPS schematics and design guides, power electronics tutorials and other free online resources for the engineers and hobbyists.

SWITCHING POWER SUPPLY DESIGN: TUTORIALS,
TEXTBOOKS

TOPOLOGIES: APPLICATION NOTES
and DESIGNS

SAMPLES of POWER SUPPLY SCHEMATICS FOR ENGINEERS AND HOBBYISTS

TI (Unitrode) seminar manuals- all topics 1983 to 2007

Linear and switching voltage regulator fundamentals

SWITCHMODE™ Reference Manual

Power Factor Correction PFC online handbook

Glossary and basic concepts

SMPS design books

POWER ELECTRONICS TECHNOLOGY- HANDBOOKS,
LECTURES, GUIDES

Fundamentals of Power Electronics (instructor's slides- see their terms of use)

Interactive online textbook- rectifier circuits, basic converters, PSPICE and mathcad simulation

Power conversion reference textbook online- drivers, applications, and components

Mathematics of electric energy, power factor and THD- definitions and equations

Online learning programs

Selection of converter topology

Switch mode voltage regulator schematics and formulas

One transistor forward converter

Off-line forward converter with active clamp and reset

Flyback - the simplest SMPS

Phase shifted ZVT (soft switched) full bridge

Current-fed push-pull circuit

Current-doubler rectifier

Half bridge converter

Push-pull converter design procedure

SEPIC Converter

Topological issues in power factor correction circuits

High Voltage reference designs

12 Volt AC-DC switching power supply: schematic, PCB, theory of operation

12VDC power supply with flyback

Switchmode PSU for car audio

Schematic of high voltage PSU for Ricoh laser printer

Transformerless power supplies: resistive and capacitive circuits