PPS: found this very interesting / enlightning page: http://www.simonbramble.co.uk/dc_dc_converter_design/flyback_converter/flyb= ack_converter_design.htm I searched in Mouser for some suitable transformer but I don't find any. Anyhow, will keep on exploring this (new for me) field. Cheers. --- PS: sorry I forgot to say that 30-50W would suffice for my application. Hi, I have made some simulations and I came to the conclusion that I can't do it via a classic inductor boost SMPS solution, exactly as you foresaw. But I have zero experience in transformer based step up circuits. Anyhow, I don't want to wound my own transformer, as this circuit may (with some hope) later become part of a production device. It needs to have an enable pin and it will be used to charge capacitors (probably around 15uF @ 400V). Any hint or guide? I wouldn't mind if as a controller I'd have to use a PIC, as I already need one in my circuit anyway and it has plenty of CPU time available also for this task, and anyway I'd like to learn something about transformer step up (or should I call it inverter?) technology anyway= , algorithms, control strategies, etc.. so an independent IC is not really necessary. Where do I start? Should I drive a couple of MOSFETs to feed the primary side of the transformer with a low voltage high current square wave? Does it have to be AC? Can't I use a pulse transformer and feed DC pulses? Things like this, to get a basic idea of what needs to be done. Thanks a lot if you / anyone else finds the time to help me, and also if you can't. Cheers, Mario At 18:23 2018-02-13, Bob Blick wrote: >Hi Mario, > >Geiger counter? Nixie clock? Photomultiplier tube? > >With that high a voltage ratio, you can't use a typical flyback +=20 >inductor topology, you will need a transformer or autotransformer. You=20 >can still use a single power device. > >Even if you lowered the switching frequency so the "off" time is still=20 >in a reasonable range for the inductor/diode/switch, most switcher=20 >chips won't go to the extreme duty cycle you'd need (98%+) to make a=20 >simple inductor work. I usually figure any voltage ratio higher than=20 >1:5 needs a transformer unless the current requirements are very very=20 >small you can push it to 1:7. Definitely not 1:50. > >On the other hand, I have made plenty of little transformers out of=20 >cheap inductors. You could wind a second layer on top of a typical=20 >"spool" inductor and you'd have yourself a fine little transformer=20 >with your hand-wound primary. Start with something like this: > >https://www.digikey.com/product-detail/en/bourns-inc/RLB9012-471KL/RLB >9012-471KL-ND/1969612 > >Peel the heatshrink off it first, and use thicker wire for your=20 >primary. And keep fingers crossed about high voltage breakdown. > >I've also salvaged transformers from electric bug swatters and photo=20 >flashes, but they need to operate at audible frequencies. > >Cheerful regards, > >Bob > > > >________________________________________ >From: piclist-bounces@mit.edu on behalf of Mario >Sent: Tuesday, February 13, 2018 2:33 AM >To: Microcontroller discussion list - Public. >Subject: [EE] 7-16V to 350-400V SMPS boost IC? > > >Hello, >could you advice me some SMPS IC (possibly with integrated MOSFET) to >boost from around 7-16V to around 350-400V with at least 1A average >input current please? > >Thank you. > >Kind regards, >Mario > >--=20 >http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .