Replacing a switch with a mosfet

Discussion in 'Homework Help' started by jonnylazer, Apr 3, 2011.

  1. jonnylazer

    Thread Starter New Member

    Jan 12, 2010
    Hi all,

    im working on a circuit at the moment that requires some peak inrush current analysis.

    If you refer to the uploaded schematic you will see that the circuit has a 24 Vdc voltage connected across its output via a switch.

    What I want to do is replace the switch with a mosfet... how can I do this ?

    hope someone can help
  2. alexan_e

    New Member

    Aug 8, 2010
    You can use a Pmosfet, source to positive battery, drain as output and drive the gate with a voltage of about 12-14v to turn on (which would give a Vgs of 10-12v) or 24v to turn off (Vgs=0)
    Assuming that you are not goind to do switching in fast rate you can use a 10k resistor from source to the gate (pull up) to keep the mosfet off when no gate signal is present, and a gate resistor of about 1K to limit the gate charge current to about 10mA, you can use lower resistor if you can provide more current.