I bought couple of motor driver(DRV8835 - pololu.com/product/2135 ) and I have been working on the motor driver circuit (DRV8835), I just want to know what is the exact operation of MOSFET here, because I would like to give direct voltage , lets say 5v to “VM” directly to IC, without any MOSFET or any peripheral components. Will it be any problem if “Vin” does not passes through MOSFET? I am really confused with these things , please give me a proper explanation to clear my doubt.
Wire the circuit as described on the product page for the DRV8835, and you should have no problems.
The purpose of the motor driver is to pass the motor power supply current to the motors, under control by the microprocessor.
The MOSFET is used for reverse voltage protection. If you connect your motor power to VIN, the full voltage of the supply will be applied to VMM as long as the power leads are not reversed. It is possible to bypass the MOSFET, but we do not generally recommend doing that.