It`s solution for supression of RF rigning prodused at Fsw>500-700KHz, in couple with shottkey diodes paralleled to controller or driver output. I saw it in appnotes from TI, example cirquit with SG1825 was working at 1,5MHz.
I can be wrong, but seems to be that both MOSFET`s arrays will be opened at same time with topology above...
Areza, you better look for some integrated drivers.
switching 8 IRF3205 in 100 ns would require 6 amp [146nc x 8 , ~ 3nf each] i guess . BD pare is good up to 3 amp [not sure , resestive/capacitive] . so 2 pare of BD would be fine for all those mosfte. dedicated driver is expencive. my gole is to use cheap and widely available component . let me know what you think about it. thanks for the replys.
well, trying to design/build a 12v push-pull smps with E65 core 3C8 material, i want to pull out few KW !?, i may be to much ambitious , but i want to try, so i m employing 16 IRF3205 total for it , cos i have that much room on the board, just a try, probably lots of smoke and fire would come out instade of KW , but who cares, lol........,
Hi
I think you got wrong approach. I not saying you should do it, but if you need few kw you would be better off with say 4 smaller toroids, each primary driven by its own pair of fets, secondarys would be connected in series, so from each one, it would produce output current but only 1/4 voltage, and because of that 1/4 of power... think about this... I am just now making push-pull too, but with up to 6 pairs of irfz44n's, one trafo, say for 1kw or so, will see how this goes
I think you got wrong approach. I not saying you should do it, but if you need few kw you would be better off with say 4 smaller toroids, each primary driven by its own pair of fets, secondarys would be connected in series, so from each one, it would produce output current but only 1/4 voltage, and because of that 1/4 of power... think about this... I am just now making push-pull too, but with up to 6 pairs of irfz44n's, one trafo, say for 1kw or so, will see how this goes
Look here:
http://cgi.ebay.com/UC3710-6A-MOSFE...Z005QQcategoryZ109455QQtcZphotoQQcmdZViewItem
Drivers up to 12A avaible from this guy, just ask him.
Sometimes he makeing auctions for these parts. Such once I won 4 TC4422 9A drivers for just $2.99 + $5.50 shipping.
@Areza
Maybe i'm kicking in an open door but did you consider modifying a existing schematic.
http://www.ep.com.pl/pobierz.php?id=12163
Sorry that its in Polish .But when i keep in mind that you folks know about electronics that shouldnt pose much problems .
(otherwise Poltran.com might help out)
http://www.ep.com.pl/pobierz.php?id=530
This is the pcb in pdf format .
I have nicer schematics but those are in Russian
At least this one has pcb's in pdf and it is builded for 8 years with succes.
(it's a welding machine for homebuilding)
Depending on choice of transformer & mosfets its capable of producing from 800 to 2500 Watts .
Monday i will get to my other computer and i can upload the Russian schematic .
Goodluck & be carefull .
Maybe i'm kicking in an open door but did you consider modifying a existing schematic.
http://www.ep.com.pl/pobierz.php?id=12163
Sorry that its in Polish .But when i keep in mind that you folks know about electronics that shouldnt pose much problems .
(otherwise Poltran.com might help out)
http://www.ep.com.pl/pobierz.php?id=530
This is the pcb in pdf format .
I have nicer schematics but those are in Russian
At least this one has pcb's in pdf and it is builded for 8 years with succes.
(it's a welding machine for homebuilding)
Depending on choice of transformer & mosfets its capable of producing from 800 to 2500 Watts .
Monday i will get to my other computer and i can upload the Russian schematic .
Goodluck & be carefull .
hi, luka, u r rite i have to redo the layout , the current one is 15cm x 15cm XFO ,CAPS and SNUB one side, MOS another side, i m trying to fit all in 10cm x 10cm, do u think it’s a bad idea to split both output of sg3525 in to 2 and drive 4 pare of bd139/140,
hi, Tolik ,i love to have them in all my smps but the price is very high over here , my target is to construct some thing affordable and easily repairable with widely available parts,
hi, Tolik ,i love to have them in all my smps but the price is very high over here , my target is to construct some thing affordable and easily repairable with widely available parts,
Hi
I drive with eacg SG output one BD139/140, just now, for my smps, I think you can drive 4 pairs(8 transistors) with easy, since only 2 are driven at the same time by each output, just remember to limit current into B of transistors, say to 100-150mA each, so there will be 200-300mA per output, and those transistors have min. hfe of 25 so output current will be high enough to drive all those fets
I drive with eacg SG output one BD139/140, just now, for my smps, I think you can drive 4 pairs(8 transistors) with easy, since only 2 are driven at the same time by each output, just remember to limit current into B of transistors, say to 100-150mA each, so there will be 200-300mA per output, and those transistors have min. hfe of 25 so output current will be high enough to drive all those fets
I have used many ferrite and powdered-iron toroied from Amidon Associates, out of Claifornia. Check out Amidon Associates
Steve
Steve
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.