* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download DC to DC Converter (Switched Mode Power Supply) Design
Ground (electricity) wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Spark-gap transmitter wikipedia , lookup
Mercury-arc valve wikipedia , lookup
Stepper motor wikipedia , lookup
Power engineering wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Power inverter wikipedia , lookup
Three-phase electric power wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Electrical substation wikipedia , lookup
Distribution management system wikipedia , lookup
History of electric power transmission wikipedia , lookup
Electrical ballast wikipedia , lookup
Current source wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Power MOSFET wikipedia , lookup
Amtrak's 25 Hz traction power system wikipedia , lookup
Integrating ADC wikipedia , lookup
Schmitt trigger wikipedia , lookup
Surge protector wikipedia , lookup
Opto-isolator wikipedia , lookup
Voltage regulator wikipedia , lookup
Stray voltage wikipedia , lookup
HVDC converter wikipedia , lookup
Alternating current wikipedia , lookup
Voltage optimisation wikipedia , lookup
Mains electricity wikipedia , lookup
DC to DC Converter (Switched Mode Power Supply) Design Why use dc/dc converters? In many designs there arises the need to convert one voltage to another. Linear regulators offer a simple low cost solution, but the heat they generate is often inefficient and bulky heat sinking is needed to dissipate the heat. A more elegant solution is a dc/dc converter (switched mode power supply). Many application notes and datasheets assume that the reader has a basic understanding of switched mode power supplies which can leave the circuit designer with a circuit that works, but he is unsure of exactly how. This article takes the reader from the very basics to the complex equations involved in dc/dc converter design and shows that switched mode power supply design can be designed with the most basic of mathematical skills. All examples are backed up with LTspice® simulations. All of the architectures below rely on a controller IC to switch a voltage across an inductor to generate the appropriate output voltage. To understand how they work, we must first understand how an inductor works. Inductors When a voltage is switched across an inductor, the current through the inductor behaves according to the equation: where V is the voltage across the inductor (in Volts), L is the inductance value (in Henries), di is the change in current (in Amps) and dt is the change in time (in seconds). Thus if a fixed voltage is applied to an inductor (of fixed value) this generates a current through the inductor that ramps up linearly with time – a constant change in current with time. When the voltage is removed from the inductor, the inductor generates its own voltage to try to maintain the current flow. Harnessing this voltage is what enables dc/dc converters to generate higher and lower voltages from the input supply. Any of the following design guides will explain the operation of the inductor in more detail. There are 4 basic types of non isolated dc/dc converter: Buck Converter Design These convert a high voltage to a lower voltage, mostly converting a positive high voltage to a positive lower voltage. Boost Converter Design These convert a low voltage to a higher voltage, mostly converting a positive low voltage to a positive higher voltage. Buck Boost Converter Design: These produce a fixed output voltage when the input voltage is either higher or lower than the output voltage. Inverting Converter Design These produce a negative voltage from a positive voltage. Many text books call this type of converter a buck boost converter, however this nomenclature is normally exclusively reserved for text books. Most practicing engineers refer to a buck boost converter as defined above. There are also several different types of isolated converter, but the one we will be discussing is the flyback converter: Flyback Converter Design These use a transformer, but driven in such a way that the primary and secondary windings appear as 2 separate inductors to the surrounding electronics. Therefore, in architecture flyback converters are very similar to boost converters. Feedback Resistor Calculator The feedback resistor values can be calculated using this spreadsheet: Feedback Resistor Calculator LTspice is a registered trademark of Linear Technology Corporation Sitemap Send Mail to: [email protected] with questions about this site sitemap: www.simonbramble.co.uk/sitemap.xml © Copyright Simon Bramble <div class="statcounter"><a title="vBulletin counter" class="statcounter" href="http://statcounter.com/vbulletin/"><img class="statcounter" src="http://c.statcounter.com/6544928/0/1298f4b5/1/" alt="vBulletin counter" /></a></div>