COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,

[Farmhand]

OMG lol, waflobs. 

https://www.youtube.com/watch?v=8WOu9uBmPN8

[TinselKoala]

I have a circuit up on my bench right now that produces a 5 ns falltime at the load , at a frequency around 270 kHz, using an ordinary IRF830n mosfet driven by a TC4420 driver chip.The driver chip is fed by the output of a Schmitt trigger inverter, and I'm using a 4.7 ohm series gate resistor between the 4420 and the mosfet Gate pin. 

[TinselKoala]

OMG lol, waflobs. 

https://www.youtube.com/watch?v=8WOu9uBmPN8

Of course. Consider the source....

[web000x]

I have a circuit up on my bench right now that produces a 5 ns falltime at the load , at a frequency around 270 kHz, using an ordinary IRF830n mosfet driven by a TC4420 driver chip.The driver chip is fed by the output of a Schmitt trigger inverter, and I'm using a 4.7 ohm series gate resistor between the 4420 and the mosfet Gate pin.

Does the fall time go up the lower the frequency you go?  I am trying to get as close to what Paul said as possible when he very seriously stated that the fall times of his switching need to be 5 ns or less.   What kind of fall time would happen if you had these mosfets running steady state DC and then shut them off?


Thanks,


Dave

[MarkE]

Does the fall time go up the lower the frequency you go?  I am trying to get as close to what Paul said as possible when he very seriously stated that the fall times of his switching need to be 5 ns or less.   What kind of fall time would happen if you had these mosfets running steady state DC and then shut them off?


Thanks,


Dave

Fall time does not have a relation to switching frequency.  It is a function of how fast charge can be driven into the MOSFET gate, and the MOSFET's characteristics: particularly drain to gate capacitance.  Pick an appropriate MOSFET, pair it with a good driver, layout the circuit properly and you can get really fast rise and fall times.