At 02:44 2018-02-14, Sean Breheny wrote: >I recently was able to make a simple boost converter (no transformer) to >provide 120V DC at 2mA from a USB 5V supply. About 70% efficiency. This is >part of a capacitance meter which can measure the variation in capacitance >vs voltage for characterizing X7R and similar ceramic chip caps, up to 100= V. 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 to 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 + induct= or >> topology, you will need a transformer or autotransformer. You can still = use >> a single power device. >> >> Even if you lowered the switching frequency so the "off" time is still i= n >> a reasonable range for the inductor/diode/switch, most switcher chips wo= n't >> go to the extreme duty cycle you'd need (98%+) to make a simple inductor >> work. I usually figure any voltage ratio higher than 1:5 needs a >> transformer unless the current requirements 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 chea= p >> inductors. You could wind a second layer on top of a typical "spool" >> inductor and you'd have yourself a fine little transformer with your >> 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 >> flashes, but they need to operate at audible frequencies. >> >> Cheerful regards, >> >> Bob >> >> >> >> ________________________________________ >> From: piclist-bounces@mit.edu on behalf of Mar= io >> 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 >> >> -- >> 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 --=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 .