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IRF3000 Minimum and Maximum Voltage

  1. Sep 10, 2011 #1
    Greetings!

    I am actually confused on what is the maximum and minimum voltage at the drain pin of IRF3000 MOSFET. Here is the datasheet: http://www.datasheetcatalog.org/datasheet/irf/irf3000.pdf

    Here is what the datasheet says: VDSS = 300V

    I wonder if this is the maximum or minimum voltage. I guess this is the maximum voltage because the characteristic curve shows Vds from 0 to 100 but I am not sure if it is correct.

    Specifically, I wanted to connect a 220VDC in series with the drain terminal of IRF3000; and a 50KHz PWM signal on the gate. I wonder if this is possible with this device.

    Please help. Thanks.
     
  2. jcsd
  3. Sep 10, 2011 #2

    vk6kro

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    Yes, further down the page it shows 300 V as the maximum breakdown voltage.

    The meaning is that all devices will have a breakdown voltage of at least this, although you might be lucky and get a device that is better than this.
    So, you have to design with this in mind.

    You will notice that these devices have a large input capacitance of 730 pF. This will have a reactance of 4.3 K ohms at 50 KHz, but to maintain a PWM square wave into this capacitance, you would have to consider the effect of this 730 pF at around 1 MHz where it would have a reactance of 218 ohms.

    I guess this would be possible, but it would be easier if you could reduce the frequency of the PWM input.
     
  4. Sep 10, 2011 #3

    vk6kro

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    You might like to have a look at this document:

    http://www.irf.com/technical-info/appnotes/an-990.pdf

    which discusses the operation of IG FETs and how to drive them. There are dedicated chips that can do it, but losses become greater at higher frequencies.
     
  5. Sep 10, 2011 #4
    On the second page, it give you the spec. That is the condition where the gate is at 0V. In another word, both gate and source are shorted at 0V. At that voltage, there will be 250uA current from drain to source.

    It is the maximum stand off voltage in the given condition.
     
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