Using an AUTOMOTIVE MOSFET IRF1405 to Control Large Current Inductive

Discussion in 'General Electronics Chat' started by SpiroTech, Jul 5, 2009.

  1. SpiroTech

    Thread Starter New Member

    Jul 5, 2009
    Hi, I am after a circuit that will control 12v to 24v inductive loads which draw large currents between 50amps to 150amps.

    I am interested in microcontrollers using PWM (Pulse Width Modulation) to drive a mosfet such as IRF1405 that will in turn control the delivery of current to the inductive load.

    Also using a potentiometer as an input to the microcontroller to control the circuit.

    Any assistants would be most welcomed.

    Cheers for now.
  2. millwood


    you will need to think about a few things:

    1) is the mosfet good enough? you will likely have Vds of about 1v with the mosfet fully on. that means a power dissipation of 150w at 150amp. assuming PERFECT heatsink, the temperature rise is 150w*0.5c/w=75c. and you derate the rated power dissipation of 330w for temperature at 2.2w/c, you get a maximum power dissipation at 74c delta of 330-2.2*75=160w. leaving no room for error.

    I would go with a beefier to3p or to247 / to264 device.

    2) gate capacitance: Cigs=5480pf. that is one monster to drive for a mcu, even at low speed. I would be very careful on that.

    3) mcu: with such large current inductor near-by, you better make sure that the mcu can operate reliably in this environment. PICs in generally have good resistance to interference.
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    I have used the LT1158 half-bridge mosfet driver for motor controllers carrying such currents . It is a bit old now and becoming expensive ($6 to 8 at Digikey). It has feedback control to take care of shoot-through etc. and needs only one pwm input. That is, your mcu will not have to generate pwm for both the top and bottom mosfets.

    Here is its datasheet:,C1,C1003,C1142,C1114,P1464,D2064

    Second, if all you want is potentiometer control, consider a dedicated motor controller to generate the pwm, unless of course, you want the mcu for other reasons.