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spindle-mosfet-control [2020/10/22 06:18]
mrscott [Spindle control with a Mosfet] Reference Wikipedia Flyback_diode.
spindle-mosfet-control [2020/10/22 06:31] (current)
mrscott [Spindle control with a Mosfet] Add more high-side inductive load switching article references.
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 If you are not using a VFD, and your spindle motor is a DC motor of low enough power (voltage and current, **including** any current extremes when stalled), you can control it directly using the MOSFETs on the Smoothieboard. If you are not using a VFD, and your spindle motor is a DC motor of low enough power (voltage and current, **including** any current extremes when stalled), you can control it directly using the MOSFETs on the Smoothieboard.
  
-MOSFETs are present on-board, but have limited current capacity ( up to 12A ) and need to be protected by a '​flyback'​ diode when controlling a motor, electromechanical relay or other inductive load.  See [[https://​en.wikipedia.org/​wiki/​Flyback_diode|Wikipedia Flyback_diode]].+MOSFETs are present on-board, but have limited current capacity ( up to 12A ) and need to be protected by a '​flyback'​ diode when controlling a motor, electromechanical relay or other inductive load.  See [[https://​en.wikipedia.org/​wiki/​Flyback_diode|Wikipedia Flyback_diode]] and [[https://​electronics.stackexchange.com/​questions/​358210/​driving-inductive-load-from-ic-with-mosfet|Driving inductive load, Electronics StackExchange]].
  
 Motors have the property of inductance, which is the electrical equivalent of inertia. ​ The motor current will continue to flow after the MOSFET is switched off, because the energy stored in the inductor by the current does not instantly disappear. ​ The current will decrease as the stored energy is dissipated. ​ This current flow results in the voltage across the motor reversing and increasing (or "​spiking"​) until the current finds a path to flow.  ​ Motors have the property of inductance, which is the electrical equivalent of inertia. ​ The motor current will continue to flow after the MOSFET is switched off, because the energy stored in the inductor by the current does not instantly disappear. ​ The current will decrease as the stored energy is dissipated. ​ This current flow results in the voltage across the motor reversing and increasing (or "​spiking"​) until the current finds a path to flow.  ​