mosfet current sensing circuit.

Discussion in 'General Electronics Chat' started by savage67, Jan 19, 2010.

  1. savage67

    Thread Starter Member

    Oct 3, 2006
    27
    0
    Hi Dears.
    i want to measure the current of power mosfet without using an current transformer. Do you know any transistor based circuit which can measure the mosfet current.
    Thanks.
     
  2. JDT

    Well-Known Member

    Feb 12, 2009
    658
    85
    Basically, insert a low value series resistor. Measure the voltage across this resistor. Use ohm's law. Amplify this voltage using a transistor circuit.

    Choose a resistor that gives about 0.5V drop at the maximum expected current. Calculate the power dissipated in the resistor at full current. Use a resistor that can handle this power.

    The problem with this arrangement is that there is no isolation between MOSFET circuit and the measuring circuit.

    Hall-effect current transformers are getting cheaper. Google.
     
  3. savage67

    Thread Starter Member

    Oct 3, 2006
    27
    0
    thanks but i mean to say transistor based circuit. like a current mirror circuit.
     
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