Simple MOSFET driver

246

06:12:48

Switching time is around 40ns which is totally enough for most applications.

published 7 years ago

gasboss775

7 years ago

If it was being used in a very fast application like a switching regulator, the discharge could be accelerated by lowering the value of the 10K resistor.

gasboss775

7 years ago

I was meaning the 10K on the left hand side BTW.

LeButch

7 years ago

@Kiani please express yourself correctly, I did not understand you. @gasboss yes. I changed it.

2ctiby

7 years ago

@LeButch ... Your lamp uses about 6mA but the whole circuit uses over 16mA ... ie: a lot of wasted current as seen by the 10mA through the 1k resistor. Also, your Mosfet settings are not set for full switching (which then does not simulate a real one in this setup). Your Mosfet has about 5v (of the 10v supply) volt drop across it which depicts a considerable heat power wastage there.

LeButch

7 years ago

Whoops, lamp and FET were connected the wrong way around...

2ctiby

7 years ago

It is looking better with the N-Mosfet connected to earth on the low side of the lamp, but really to make a lamp work with a Mosfet you don't need any bjt transistors extra. The 1k resistor there is still using 10mA and the mosfet settings need adjusting.

eekee

7 years ago

@kiani: 40ns is not very slow in relation to most tasks. :) For instance, with this example load, I don't think a bulb could react that fast and I'm certain the human eye couldn't. It's a matter of proportion. Also, fast switching can be a problem, requiring more careful PCB layout etc. 40ns is already fast enough to require it.

LeButch

7 years ago

Well, then you can still use a really really really really really small resistor for the job.

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