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 100V=
..

On Feb 13, 2018 12:24 PM, "Bob Blick" <bobblick@outlook.com> wrote:

> Hi Mario,
>
> Geiger counter? Nixie clock? Photomultiplier tube?
>
> With that high a voltage ratio, you can't use a typical flyback + inducto=
r
> topology, you will need a transformer or autotransformer. You can still u=
se
> a single power device.
>
> Even if you lowered the switching frequency so the "off" time is still in
> a reasonable range for the inductor/diode/switch, most switcher chips won=
'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 cheap
> 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 <piclist-bounces@mit.edu> on behalf of Mari=
o
> 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
>
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