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Why do I need a Schottky diode?
Schottky diodes are used for their low turn-on voltage, fast recovery time and low-loss energy at higher frequencies. These characteristics make Schottky diodes capable of rectifying a current by facilitating a quick transition from conducting to blocking state.
How do I get rid of back EMF?
Since getting rid of all the inductors is not possible, we have to suppress this back EMF. The most common technique with DC switching is to use a diode in parallel with the relay coil (aka freewheeling diode) as shown in Figure 1a. When the load is energized the diode is back biased and has no effect.
What is the difference between emf and back EMF?
If an open coil is subjected to a variable magnetic field, at the ends of the coil a potential difference is induced which is called induced emf. If a coil is connected to an emf source and switched on, the rising current will produced an variable magnetic field which in turn produces an emf. It is called back emf.
Why do I need a Schottky diode as a flyback diode?
Schottkys have effectively instant reverse recovery for your purpose. The lower forward voltage of the Schottky will also cause less backwards EMF on the inductance during the off time, making the overall system more efficient. I see there is some discussion about comparing the PWM period with the reverse recovery time.
Why is a Schottky diode bad for an inductor?
This is not really relevant since with fast enough PWM the diode is forward-conducting during the whole off interval. The recovery time issue occurs at the start of the on time. Until the diode turns off, it looks like a short across the load. This is bad for the switching transistor, bad for the diode, and wastes a lot of power.
Can you use a diode with fast reverse recovery?
Yes, you should really use a diode with fast reverse recovery. A Schottky is a obvious choice at this low voltage. Schottkys have effectively instant reverse recovery for your purpose. The lower forward voltage of the Schottky will also cause less backwards EMF on the inductance during the off time, making the overall system more efficient.
Why does ESC use built in diodes for brake FETs?
A lot of ESC seem to use the built in diode of the brake fets for back EMF protection, & i doubt that those protection diodes are up to handling the high currents / voltages being generated by a high reving car motor.