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Old 11-23-2010, 07:43 PM   #4044 (permalink)
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Originally Posted by DJBecker View Post
I was traveling and missed this post the first time around.

If the Darlington pair couldn't handle the frequency, or were not driven strongly enough to put the output into saturation, they wouldn't be full on or full off. They would be somewhere in the middle. It doesn't take long for them to effectively melt -- enough internal dopant diffusion happens for them to become low value resistors..
Sorry chaps, have not been keeping up to date lately, has anyone pointed out that driving darlingtons (or any BJT) is a different challenge to MOSFETs and IGBTs. Straining the memory a bit here but one is about supplying current and the other is about supplying voltage. Yes I know that the two are inseparable but there is definitely different approach to each. My point being that a circuit that is perfectly suited to driving MOSFETs is very likely not suited to driving Darlingtons.
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