Hi,

I don't know how to design a motor driver circuit using MOSFET for driving the motor. what are the parameters to be considered while selecting a mosfet. How do we calculate the resistor values. how do we select the diode. I have attached a reference schematic that I came across ,kindly help me to understand.

Thank You

 

The two most important parameters are the max drain to source voltage and the nax drain current.

Can you tell what the those must be for your circuit? Hint: for both of these parameters it is okay if the they are higher than required.

 

What is the motor rated operating current and voltage?

 

The parameter that is often overlooked is the startup current. When power is first applied, the load is the stalled resistance of the motor, which is usually very low. This can damage the controlling MOS FET if its current or power rating is exceded. When the stall current is high, several MOS FETs can be connected in parallel, using the same heat sink and driven by the common switching source.

 

It is also necessary to positively insure that the Gate-Voltage changes very fast, and decisively,
from zero-Volts, to the Gate-Voltage required for the rated minimum "Rds-On" Resistance.
This is commonly between ~6-Volts and ~10-Volts depending upon the particular FET's Specifications.
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I think we've answered this already
https://forum.allaboutcircuits.com/threads/how-to-design-mosfet-as-a-switch.199561/#post-1894003

 

High start current can be eliminated when using the PWM function to control the motor, just introduce a start ramp up.