The FET's (and diodes) I'm using, are well within the specs. None of those show any sign of heat at all. Also, I am using FET's with low QG/Rds etc.
My own supply uses a current-sense resistor, which I can be used for measuring purposes. Most of the commonly used supplies runs around 40-60kHz, and uses 100uH inductors (DCM). I am actually looking into using (much) higher inductance and higher frequencies. So far simulations looks OK, and I get "CCM-ish" curves and reasonably good efficiency. Will do some more simulations before I make a test board. What particular things are you thinking about ? On Tuesday, November 6, 2018 at 6:02:48 PM UTC+1, gregebert wrote: > > Also, be sure to use a scope and look carefully through the design. The > switching device (most likely a MOSFET) is susceptible to voltage > overstress, so make sure the drain-source voltage is not exceeded, and > especially not the gate-source voltage because it is a very thin oxide that > can only withstand low voltages, on the order of 10-20 volts. > > If you can place a small resistor, say 0.1 to 1.0 ohms, between the source > lead and GND, you can use a scope to monitor peak transistor current, which > in-turn will be the peak inductor current. It must remain below Isat. > > The transistor is subject to heating as well, depending upon its Rds (on) > spec and the RMS current thru the inductor. Switching losses are probably > small, but the only way to know is to measure the drain-source voltage > simultaneously with the drain current. Some fancy scopes might calculate > this for you, otherwise you can export data-samples to excel and calculate > the switching energy per-cycle. > > Knowing the RMS current thru the inductor, and it's resistance, you can > calculate the resistive power dissipation; this does NOT include any > magnetic losses due to hysteresis or saturation. > > If you are running at high frequencies, such as hundreds of kilohertz, > other things will creep-in and bite you. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/ba87e0c4-3c33-4923-89e8-64814ff7fde7%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
