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Recirculation Diode

Recirculation diodes are used to to return ("recirculate") any voltage that is higher than the supply voltage on the ground side of a inductor back to the supply. This is necessary because the inductor acts like a voltage source when the current is stopped, and its voltage can rises quite high for brief periods. This is called a 'flyback spike'. The flyback spike can damage components if it isn't effectively dealt with. The flyback spikes are particularly a problem with pulse width modulated (PWM) devices, primarily because there is a flyback spike on every cycle.

Frequent flyback spikes can also generate a lot of electrical noise that can interfere with VSS and ISS signals.

To implement a recirculation diode using the common 1N4001 diode, follow these steps:

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© 2011, 2015 Bruce Bowling and Al Grippo. All rights reserved. MegaSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of MegaSquirt® boards from Bowling and Grippo.