Strange MOSFET driver behaviour - Microchip TC4426
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From: John Larkin on 10 May 2010 17:32 On Mon, 10 May 2010 13:32:06 -0700 (PDT), Didi <dp(a)tgi-sci.com> wrote: >On May 10, 11:06�pm, John Larkin ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> On Mon, 10 May 2010 09:53:57 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >> >Not so long ago I put them in a design (the other Microchip part which >> >has >> >made it into my designs is an I2C EEPROM). >> >Worked as expected while driving tiny MOSFETs (two in an SO-8). >> >> We've used MAX4420s to drive NTP15N40s through gate drive transformers >> and they were so fast we had to add gate resistors to slow things >> down. We switched 400 volts in something like 10 ns, as I recall. >> >> John > >Have never tried them, just had a look - look really fast, being >single >driver per SO-8 is apparently for a reason :-). > >But my losses are mostly in the inductors - which I will have to >address >if I am to offer this for battery operation. One flyback transformer >is >on an iron powder core and is absolutely marginal at max power (where >it >won't get, OK), efficiency is 60 to 70% at most. I know you have been >through that, is there a lot to gain by using kool mu or MPP? >Something like 10W max., I am doing it at about 500 kHz. > >Dimiter Powered iron is horrible for switchers; AC losses get huge as flux density increases. MPP is great (more energy storage per volume, much less loss) but expensive. KoolMu is almost as good as MPP and a lot cheaper. Somebody else, maybe Micrometals, has an equivalent to KoolMu. I've burned the paint off powdered iron cores in buck regulators. John
From: Joerg on 10 May 2010 18:42 John Larkin wrote: > On Mon, 10 May 2010 13:32:06 -0700 (PDT), Didi <dp(a)tgi-sci.com> wrote: > >> On May 10, 11:06 pm, John Larkin >> <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>> On Mon, 10 May 2010 09:53:57 -0700 (PDT), Didi <d...(a)tgi-sci.com> wrote: >>>> Not so long ago I put them in a design (the other Microchip part which >>>> has >>>> made it into my designs is an I2C EEPROM). >>>> Worked as expected while driving tiny MOSFETs (two in an SO-8). >>> We've used MAX4420s to drive NTP15N40s through gate drive transformers >>> and they were so fast we had to add gate resistors to slow things >>> down. We switched 400 volts in something like 10 ns, as I recall. >>> >>> John >> Have never tried them, just had a look - look really fast, being >> single >> driver per SO-8 is apparently for a reason :-). >> >> But my losses are mostly in the inductors - which I will have to >> address >> if I am to offer this for battery operation. One flyback transformer >> is >> on an iron powder core and is absolutely marginal at max power (where >> it >> won't get, OK), efficiency is 60 to 70% at most. I know you have been >> through that, is there a lot to gain by using kool mu or MPP? >> Something like 10W max., I am doing it at about 500 kHz. >> >> Dimiter > > Powered iron is horrible for switchers; AC losses get huge as flux ^^^^^^^^^^^^ Some new type of weapon? :-) > density increases. MPP is great (more energy storage per volume, much > less loss) but expensive. KoolMu is almost as good as MPP and a lot > cheaper. Somebody else, maybe Micrometals, has an equivalent to > KoolMu. > I am pretty happy with ferrite. > I've burned the paint off powdered iron cores in buck regulators. > I've exploded an Amidon T200-2. *KABOOM* ... followed by about 120ft worth of wire antenna smacking onto the ground. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Tim Williams on 10 May 2010 18:45 "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:ahugu5pdtr3t8r5uqcecguqhan70khf57a(a)4ax.com... > Powered iron is horrible for switchers; AC losses get huge as flux > density increases. MPP is great (more energy storage per volume, much > less loss) but expensive. KoolMu is almost as good as MPP and a lot > cheaper. Somebody else, maybe Micrometals, has an equivalent to > KoolMu. Avoid yellow/white mix 26 if possible. It's cheap, so you can give up flux density for dollars, if space and weight allows. I see green/blue mix 52's on motherboards a lot, which apparently has about half the losses of 26, for slightly more price. I haven't seen any other grades used in consumer equipment, just those and ferrite. I think Micrometals' products are all numbered. I'd guess 52 is the equivalent you speak of, but I don't have a reference for that. At high frequencies, gapped ferrite looks best. Only 0.4T Bmax, but you can use the whole damn B-H curve, not some teensy fraction of it. At about 100kHz, in regular sizes, ferrite has the same power density as mix 26, which might overheat for 0.2T or less DeltaB. (If you need filtering, 26 is great because B_DC goes up to 1-1.2T.) Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: tm on 10 May 2010 19:35 "Joerg" <invalid(a)invalid.invalid> wrote in message news:84raq0F5kuU1(a)mid.individual.net... >> > > Our Rottweiler is 13 and you can see the he's failing. I dread that day > but we have to be there for them until the end. Contrary to scientific > beliefs animals can do rational thinking and planning. Our Sheperd has > done stuff when she was younger, for example stealing a freshly baked roll > from underneath an aluminum foil wraper, _then_ putting the wrapper back > on. The crumbs in her basket evidenced the mischief though, she didn't > have enough time to clean that up. You could literally see that "Darn!" > expression on her face. > > -- Here are our two Bostons. http://www.youtube.com/watch?v=FpLsc1mOoGk He's pretty smart. Tom
From: Joerg on 10 May 2010 21:13
tm wrote: > "Joerg" <invalid(a)invalid.invalid> wrote in message > news:84raq0F5kuU1(a)mid.individual.net... >> Our Rottweiler is 13 and you can see the he's failing. I dread that day >> but we have to be there for them until the end. Contrary to scientific >> beliefs animals can do rational thinking and planning. Our Sheperd has >> done stuff when she was younger, for example stealing a freshly baked roll >> from underneath an aluminum foil wraper, _then_ putting the wrapper back >> on. The crumbs in her basket evidenced the mischief though, she didn't >> have enough time to clean that up. You could literally see that "Darn!" >> expression on her face. >> >> -- > > Here are our two Bostons. > > http://www.youtube.com/watch?v=FpLsc1mOoGk > > He's pretty smart. > Amazing. If he'd be a human he'd probably be doing hard time already :-)) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |