A switched inductor without and with flyback diode for voltage spike suppression

A flyback diode (sometimes called a snubber diode, freewheeling diode, suppressor diode, or catch diode[1]) is a diode used to eliminate flyback, the sudden voltage spike seen across an inductive load when its supply voltage is suddenly reduced or removed. A flyback diode provides a discharge current path for the energy stored in the load, which allows that energy to dissipate slowly, rather than appearing as a voltage spike as it dissipates instantaneously. In mechanically-switched circuits, the near-instantaneous dissipation which occurs without a flyback diode is often observed as an arc across the opening mechanical contacts, resulting in the energy's dissipation as electro-magnetic energy including everything from visible light to a wide spectrum burst of radio-frequency noise, while causing premature erosion of the contacts. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A snubber is a simple electrical circuit used to suppress (snub) electrical transients. ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a component that restricts the directional flow of charge carriers. ... A flyback transformer or line output transformer (LOPT) is a type of transformer used to generate the high voltage needed for driving a cathode ray tube or picture tube. It converts the input voltage, usually mains voltage in the range 120 to 240 volts, to an output voltage in the... An electric current i flowing around a circuit produces a magnetic field and hence a magnetic flux Φ through the circuit. ... If an electric circuit has a well-defined output terminal, the circuit connected to this terminal (or its input impedance) is the load. ...

Applications: Flyback diodes are used whenever inductive loads must be switched off: in relay drivers, H-bridge motor drivers, and inside the switched-mode power supply. Automotive style miniature relay A relay is an electrical switch that opens and closes under the control of another electrical circuit. ... An H-bridge is an electronic circuit which enables DC electric motors to be run forwards or backwards. ... A switching-mode power supply for laboratory use. ...

Design: Schottky diodes are preferred in flyback diode applications, because they have the lowest forward drop and the fastest (but still "soft") reverse voltage recovery. In applications which require higher "reverse blocking voltage" than Schottky diodes offer, the "gold doped diode" is preferred as the next most efficient diode choice[2]. Schottky diode schematic symbol 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. ...

Low-cost applications unconcerned with efficiency often use 1N4004 or 1N4005 or 1N4007 power diodes as flyback diodes (sci.electronics.design : "diode for relay coil spikes and motor shutoff spikes?").