Very good! Something more people should be paying attention to, I think. -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= Mario Sent: Wednesday, February 14, 2018 11:14 AM To: Microcontroller discussion list - Public. ; Microcontr= oller discussion list - Public. Subject: Re: [EE] 7-16V to 350-400V SMPS boost IC? At 02:44 2018-02-14, Sean Breheny wrote: >I recently was able to make a simple boost converter (no transformer)=20 >to provide 120V DC at 2mA from a USB 5V supply. About 70% efficiency.=20 >This is part of a capacitance meter which can measure the variation in=20 >capacitance vs voltage for characterizing X7R and similar ceramic chip cap= s, up to 100V. Coolness. Few know of this characteristic/limit of MLCC's, but much fewer actually do= even design tools to measure it. I would never use a MLCC where this info is not specified in the datasheet. I found that TDK does a very good job on it, but then again having a tool t= o actually measure this is very cool. Congratulations. > >On Feb 13, 2018 12:24 PM, "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.=20 >> You can still use a single power device. >> >> Even if you lowered the switching frequency so the "off" time is=20 >> still in a reasonable range for the inductor/diode/switch, most=20 >> switcher chips won't go to the extreme duty cycle you'd need (98%+)=20 >> to make a simple inductor work. I usually figure any voltage ratio=20 >> higher than 1:5 needs a transformer unless the current requirements=20 >> are very very 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 "spoo= l" >> inductor and you'd have yourself a fine little transformer with your=20 >> hand-wound primary. Start with something like this: >> >> https://www.digikey.com/product-detail/en/bourns-inc/ >> RLB9012-471KL/RLB9012-471KL-ND/1969612 >> >> Peel the heatshrink off it first, and use thicker wire for your 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=20 >> 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=20 >> boost from around 7-16V to around 350-400V with at least 1A average=20 >> input current please? >> >> Thank you. >> >> Kind regards, >> Mario >> >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 >> View/change your membership options at=20 >> http://mailman.mit.edu/mailman/listinfo/piclist >> >-- >http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 >View/change your membership options at=20 >http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=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 .