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Topic: Output 5V to mosfet. (Read 872 times) previous topic - next topic


I had for years problem letting digital output 5V make a mosfet work together with logic 5V. There is a big missunderstanding what voltage is required to make a mosfet fully draw with minimum voltage drop RDS and heat. Since a mosfet VGS is the voltage 10V where the data is measured there is a problem when you only have 5 V. The VGS treshold in the voltage where the mosfet start to drop, NOT draw. 
I first solved this with using a NPN transistor with the mosfet. I used that for a while until i found the FDS6680A mosfet with true logic input at the gate. At 4.5V gate voltage you can draw 12.5 A, 30 V. The bad thing is it is SMD mounted but the good thing is it SOP8 pin and 3 pin is connected as DRAIN, 3 pin connected as SOURCE and 2 pin connected as GATE. So its easy to solder. 

They are very cheep, Aliexpress 10pcs for 2usd.



Yes, the logic level mosfets are really handy when your interfacing to microcontrollers/microprocessors.  I have a electronic load I bought from China and they use the mosfet drain to source as a variable resistor by varying the gate to source voltage. It comes with a big fan sitting on top of it to dissipate the heat.

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