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flyback diode

Flyback diodes are overvoltage protection diodes. They are mainly used to avoid voltage peaks when switching off inductive loads such as relays, coils

, electric motors and solenoids. In these components, large voltage spikes occur during switch-off due to the collapse of the magnetic field, which could damage or destroy sensitive semiconductor components.

To avoid the overvoltage spikes, the freewheeling diode is connected in parallel with the inductive load in such a way that they are operated in the reverse direction from the supply voltage. The freewheeling diode limits the voltage peaks to the forward voltage of the diode.

Free-wheeling diode in parallel with the inductive load

Free-wheeling diode in parallel with the inductive load

Due to self-induction, high voltage peaks occur when the supply voltage is switched off by the stored magnetic energy, which are limited by the free-wheeling diode. This must be dimensioned so that it can absorb the load current for a short time.

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Englisch: flyback diode
Updated at: 30.05.2014
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Translations: DE