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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Alex1M6 wrote ...
Sorry, what does linear resistance portion mean? is it something to do with the MOSFET not being driven correctly and that causes heating?
I have not got and TVS yet as I want to be sure that I am buying components that are going to do the job in protecting the MOSFET.
The TVS's youll buy depend on the Mosfet youll use, also yes if you dont drive the MOSFet you can cause it to over heat, TVS's only prevent overvoltage, your heat problem can also be an current problem. I use the FAN738N in my circuits.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Alex1M6 wrote ...
Ok so it just goes in parallel with the MOSFET? and why didn't the MOSFET's built in protection diode alone protect it?
Remember a diode conducts in one direction and not in the other. the TVS functions the same way, until the clamping voltage is reached, then it will clamp to the speced voltage, direction of the apllied voltage matters.
...remember that the inductor EMF is in the opposite direction of the intial voltage put into it.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Alex1M6 wrote ...
Ok so is this what happens?
Yes, my brain is hurting though, dam it.
EDit: you can increase the turns on your primary if you want lower curretn than 10 amps, mine uses 30T, and draws 4 amps @ 85 volts (with 65 volts across the 30T primary. 4 amps through it) And my freq is about 15kHz at a 30% Duty Cycle.
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555 flyback transformer MOSFET gets hot.
