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MOSFET tutorial

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AGCB

Member
Would someone steer me to a good tutorial on using power MOSFETs. Especially with PICs. I'm trying to make a 3 amp lamp control circuit with PWM. I have a IRF740 MOSFET to experiment with. Thanks
 

MikeMl

Well-Known Member
Most Helpful Member
Start by downloading and reading the Data Sheet
 

crutschow

Well-Known Member
Most Helpful Member
This is a good place to start.
 

Frosty_47

New Member
Keep in mind that power MOSFETS have large Gate to Source Capacitance (around 8nF-12nF). This capacitance can distort your square waveform significantly if you do not provide sufficient current from your driving circuit. Use a high quality pass transistor to drive the POWER MOSFET. This way you can supply more current and charge the Gate faster hence reducing any "edge rounding" of your square wave. Remember not to exceed the Vgs and Vds ratings at any time. 15V is a good Vgs value for most power N-Channel MOSFETS. A Vgs value below 5V will keep the mosfet in cutoff mode. Also the Drain to Source resistance decreases with increase in Vgs, so your MOSFET will stay cooler. I suggest you visit digikey.com and have a look at the various MOSFETS available.

Hope this helps you a bit...
 

AGCB

Member
Thanks for the replies. I found out about the capacitances by experiment, also the logic level devises , which I do not have. Got the circuit working with a discreet darlington araingment with BPTs. Next time I order parts I'll get some more MOSFETs to monkey with.
 

Frosty_47

New Member
Thanks for the replies. I found out about the capacitances by experiment, also the logic level devises , which I do not have. Got the circuit working with a discreet darlington araingment with BPTs. Next time I order parts I'll get some more MOSFETs to monkey with.

Experiment is often the best way to learn, though it can cost 2 much...
 
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