In this post, I am gonna share a hanging problem of a microcontroller that is related to back emf. I faced this problem when I was using the Arduino microcontroller in a high-speed switching circuit. The microcontroller stops working a few seconds after switching on the circuit. No damage to the microcontroller in my case, after reset microcontroller works in the same way.
When we use devices like relay or motors with microcontrollers and operate them through a driver IC. During switching on and off there is back emf generated. This back emf can cause damage to the microcontroller.
What is back emf? Inductor has a property that current cannot change instantaneously through them. Due to this property when we remove supply from inductor the current flowing through it needs a path. When it finds no low resistance path large voltage spike is produced. Why? It takes the high resistance path which can be insulator or air. This high voltage spike can damage our equipment.
How to solve this problem? To solve the problem we should provide a low resistance path to this current. When this current goes through a low resistance path, the voltage developed becomes negligible. Usually, in circuits high-speed diode is used for this purpose. See the figure below how current passes through the diode when the switch opens at t=0.
When we use devices like relay or motors with microcontrollers and operate them through a driver IC. During switching on and off there is back emf generated. This back emf can cause damage to the microcontroller.
When the switch opens at t=0 the current 'I' sees high resistance. This high resistance path can be any insulator or air itself.
What is back emf? Inductor has a property that current cannot change instantaneously through them. Due to this property when we remove supply from inductor the current flowing through it needs a path. When it finds no low resistance path large voltage spike is produced. Why? It takes the high resistance path which can be insulator or air. This high voltage spike can damage our equipment.
How to solve this problem? To solve the problem we should provide a low resistance path to this current. When this current goes through a low resistance path, the voltage developed becomes negligible. Usually, in circuits high-speed diode is used for this purpose. See the figure below how current passes through the diode when the switch opens at t=0.
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