Motor control

Discussion in 'The Projects Forum' started by psy1794, Oct 7, 2011.

  1. psy1794

    Thread Starter New Member

    Sep 26, 2011
    hi im using microcontroller to input the pwm waveform to the gate of the mosfet but the problem is that in the datasheet the mosfet needs to be supplied 10v to be fully on. we are only getting 5v from the micro output.
    can some one give me a circuit or a idea or any components to achieve 10v or to release the heat building up on the mosfet.
    we are using a IRF1405 mosfet
  2. crutschow


    Mar 14, 2008
    That's a very large MOSFET. Do you really need that much current capacity?

    The problem with such a large MOSFET is that it has a large gate capacitance and requires the rapid addition and removal of a large amount of charge (260nC max. for this device) to switch the MOSFET. Thus, for example, to switch the transistor in 100ns requires a current drive of 260nC/100ns = 2.6A.

    A driver such as the IR2121 may work for you.
  3. #12


    Nov 30, 2010
    There are "logic level" mosfets. I haven't used any, but it's a look-up search away at a vendor site like mouser, jameco, digikey, etc.
  4. crutschow


    Mar 14, 2008
    That's true. But in the large size that they are using, the microcontroller would not have near enough current drive capability to rapidly switch the large value of gate capacitance on and off.