Author Topic: A quick(ish) MOSFET tutorial  (Read 3341 times)

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Offline Sivand12Topic starter

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A quick(ish) MOSFET tutorial
« on: November 18, 2014, 11:16:56 am »
Here is the Introductory video.


Offline PODF

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Re: A quick(ish) MOSFET tutorial
« Reply #1 on: February 27, 2015, 05:55:17 pm »
thanks, this video helpt me a lot.

but i have a question with the VGS. In the case of the IRFZ44N from this video (http://www.irf.com/product-info/datasheets/data/irfz44n.pdf). Can i run this MOSFET with VGS only +5V and get around 10A switched? Figure 3 tells me that this is working (by the way, how do i read this graph? where is it starting at +5V? 10A? 12A? 20A? 50A??? the squares in this figure are asymmetric). Is this ok to run MOSFETS like this? Or is this bullshitt? Is the resistance much higher when VGS i only +5V? I dont see a RDS graph in relation to VGS??
 

Offline retrolefty

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Re: A quick(ish) MOSFET tutorial
« Reply #2 on: February 27, 2015, 09:57:47 pm »
thanks, this video helpt me a lot.

but i have a question with the VGS. In the case of the IRFZ44N from this video (http://www.irf.com/product-info/datasheets/data/irfz44n.pdf). Can i run this MOSFET with VGS only +5V and get around 10A switched? Figure 3 tells me that this is working (by the way, how do i read this graph? where is it starting at +5V? 10A? 12A? 20A? 50A??? the squares in this figure are asymmetric). Is this ok to run MOSFETS like this? Or is this bullshitt? Is the resistance much higher when VGS i only +5V? I dont see a RDS graph in relation to VGS??

 No, a 'logic level' mosfet is what is required for 5vdc VGS drive. Lots to choose from.

 

Offline suicidaleggroll

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Re: A quick(ish) MOSFET tutorial
« Reply #3 on: February 27, 2015, 10:24:30 pm »
thanks, this video helpt me a lot.

but i have a question with the VGS. In the case of the IRFZ44N from this video (http://www.irf.com/product-info/datasheets/data/irfz44n.pdf). Can i run this MOSFET with VGS only +5V and get around 10A switched? Figure 3 tells me that this is working (by the way, how do i read this graph? where is it starting at +5V? 10A? 12A? 20A? 50A??? the squares in this figure are asymmetric). Is this ok to run MOSFETS like this? Or is this bullshitt? Is the resistance much higher when VGS i only +5V? I dont see a RDS graph in relation to VGS??

It's a logarithmic scale, that's why the lines aren't linear.  The first horizontal line above 10 is 20, then 30, 40, and so on up to 100, then the next line is 200, 300, etc.

Read the caption on Figure 3.  That's the drain to source current with a Vds of 25V.  You can see that at a Vgs of 5V and a Vds of 25V you get ~20A at room temperature, which is an Rds of over an ohm.  If you want to run 10A through it, you'll be dropping around 12V across Vds and burning around 120W in the MOSFET.  At least for a few milliseconds until it dies.
« Last Edit: February 27, 2015, 10:26:25 pm by suicidaleggroll »
 

Offline PODF

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Re: A quick(ish) MOSFET tutorial
« Reply #4 on: March 02, 2015, 11:06:00 am »
Thanks suicidaleggroll, for the scale and for the Vds of 25V-hint.
I thought this Figure shows that at Vgs 5V there could only be 20A transferred.
But thats wrong, it more shows the resistance of the MOSFET.
so, i have to go the top of Figure 3 to get the least resistance.
Minimum Vgs 10V in this case.
 


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