vapaakytkentädiode

Vapaakytkentädiode, also known as a flyback diode or freewheeling diode, is a semiconductor device used to protect electronic components from voltage spikes. These spikes can occur when an inductive load, such as a motor or relay coil, is switched off. When the current to the inductor is suddenly interrupted, the inductor's magnetic field collapses, inducing a high voltage in the opposite direction. This induced voltage can be significantly higher than the supply voltage and can damage other components in the circuit.

The vapaakytkentädiode is connected in parallel with the inductive load, but in reverse bias. This means that under normal operation, when the switch is closed and current is flowing through the inductor, the diode is not conducting. However, when the switch opens and the induced voltage tries to push current in the opposite direction, the diode becomes forward-biased and conducts. This provides a path for the inductor's stored energy to dissipate safely, typically as heat within the diode and the inductor's winding, preventing the voltage spike from damaging other parts of the circuit.

In essence, the vapaakytkentädiode "catches" the flyback voltage, allowing it to freewheel harmlessly. This protection is crucial in many electronic circuits, especially those involving switching of inductive loads. The diode's speed of response is important, and fast-switching diodes are often preferred for applications where rapid transients occur. Its placement is critical to ensure it effectively shunts the unwanted voltage.