Speaking of nuggets, here's a real gem of information for you ... Did you know that sometimes I make stuff up in these columns. Not the technical stuff, but some of the silly stuff. Over the years I have created a bunch of fictitious relatives, and lots of strange adventures. I hope my readers will accept this confession in the spirit in which it is offered. Maybe my personal life isn't all that interesting. Maybe I am a nerdish little fellow living a dark room full of empty delivery cartons of Chinese food. Maybe my white things do come out of the laundry a little dingy. --- What was I writing about? Please forgive this ridiculous stream of consciousness. I must have missed my 4pm medication.
If you were driving the gate of a large N-channel MOSFET transistor, with a microcontroller output that has an internal resistance of 200 ohms, how long will it take to get the gate voltage up to the full Vgson of 4 volts? The CPU is running on a 5 volt supply, the FET source is at the CPU ground potential, and the gate-source capacitance of the FET is 15 pF. Let's ignore the effects of the drain circuit for this exercise. This is an important consideration, since this period is the time of greatest power dissipation in switching transistors.
Please don't think less of me because my clothes may not be perfectly laundered. I had a difficult childhood.
Reply to Butch Shadwell by August 20 at (email), 904-223-4510 (fax), 904-223-4465 (v), 3308 Queen Palm Dr., Jacksonville, FL 32250-2328. (http://www.shadtechserv.com) The names of correct respondents may be mentioned in the solution column.