- Synchronous rectification
The synchronous rectification is a technique for improving efficiency of
power converters in power electronics. It consists of connecting a diodeand a transistor(usually a power MOSFET) in parallel. When the diode is forward-biased, the transistor is turned on, to reduce the voltage drop. When the diode is reverse-biased, the transistor is turned off, so no charge can flow through the circuit. This way, a rectifying characteristic is obtained, without the forward voltage drop associated with diodes in the on-state.
In low voltage converters (around 10
voltsand less), the voltage drop of a diode (typically around 1 volt for a silicon diode at its rated current) has a very negative effect on efficiency. One classic solution consists of using Schottky diodes, which exhibit very low voltage drops (as low as 0.3 volts). However, when addressing very low-voltage converters, such as the buck converters that deliver power to the CPUof a computer (voltage is around 1 volt), this is no longer an adequate solution for good efficiency.
On the other hand, the transistors used in these very low-voltage converters are usually MOSFETs. These transistors behave like a resistor, so providing their resistance is low enough (for example by paralleling several devices), their voltage drop can be very low. Furthermore, MOSFETs have an intrinsic diode between their source and drain terminals. This makes these transistors useful for synchronous rectification: They can directly replace the freewheeling diode in converters. They behave inherently like a diode, and when they are turned on (via a control circuit), they behave as a low value resistance, yielding lower losses.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Buck converter — A buck converter is a step down DC to DC converter. Its design is similar to the step up boost converter, and like the boost converter it is a switched mode power supply that uses two switches (a transistor and a diode) and an inductor and a… … Wikipedia
DC-to-DC converter — An assortment of 78xx series ICs, linear DC DC converters A DC to DC converter is an electronic circuit which converts a source of direct current (DC) from one voltage level to another. It is a class of power converter. Contents … Wikipedia
Schottky diode — The Schottky diode (named after German physicist Walter H. Schottky; also known as hot carrier diode) is a semiconductor diode with a low forward voltage drop and a very fast switching action.In the early days of wireless, cat s whisker detectors … Wikipedia
Импульсный стабилизатор напряжения — Импульсный стабилизатор напряжения это стабилизатор напряжения, в котором регулирующий элемент работает в ключевом режиме, то есть большую часть времени он находится либо в режиме отсечки, когда его сопротивление максимально, либо в… … Википедия
Rectifier — A rectifier is an electrical device that converts alternating current (AC) to direct current (DC), a process known as rectification. Rectifiers have many uses including as components of power supplies and as detectors of radio signals. Rectifiers … Wikipedia
Vacuum tube — This article is about the electronic device. For experiments in an evacuated pipe, see free fall. For the transport system, see pneumatic tube. Modern vacuum tubes, mostly miniature style In electronics, a vacuum tube, electron tube (in North… … Wikipedia
generator — An apparatus for conversion of chemical, mechanical, atomic, or other forms of energy into electricity. [g., a begetter, producer] aerosol g. a device for producing airborne suspensions of small particles for inhalation therapy or experimental … Medical dictionary
Rotary converter — A rotary converter is a type of electrical machine used to convert one form of electrical power into another form. There are several types:* Rotary Phase Converter (RPC) for converting single phase power to three phase power. See Rotary phase… … Wikipedia
Weapons of Star Trek — The Star Trek fictional universe contains a very large number of weapons.Energy weaponsDisruptorsDisruptors are employed by the Romulan Star Empire, Klingon Empire, Breen, Cardassian Union, and Orions in their personal and military small arms as… … Wikipedia
Switched-mode power supply — switched mode power supply. A bridge rectifier B Input filter capacitors C Transformer D output filter coil E output filter capacitors ] A switched mode power supply, switching mode power supply or SMPS, is an electronic power supply unit (PSU)… … Wikipedia