Re: high voltage boost DC/DC converters (5V->250V)


"Michael" <nleahcim@xxxxxxxxx> wrote in message
news:9961350e-5009-4c7a-97c7-3d2f8cbc5ad5@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi there - at work I'm probably going to have to design a high voltage
DC/DC converter sometime in the near future. It looks like it'll be
something along the lines of 5V input and 250V output. Current will be
under 10ma. Probably more like 1-2ma. The more regulated the better,
but I will probably just regulate it down a bit with a FET to clean it
up.

My understanding is that once you start to get to something like an
output voltage 10x or more of the input voltage the standard boost
circuit (cap + diode + inductor) no longer really cuts it. Instead,
I've read that step-up transformers are a better way to go. However,
when I look through Digi-Key, all I see are step down transformers for
stepping down wall power, as well as various specialty transformers.

Any suggestions? Thanks!

-Michael
If you really want to do it on the cheap, get a 60 Hz 120:6VCT transformer.
Apply push pull drive to the 6V windings at about 100 Hz, and take the HV
off the 120 winding with a full wave doubler circuit. You will want to take
the drive off a Dff to insure 50% duty cycle, otherwise there will be a DC
component in the transformer. There should be a reasonable looking square
wave on the 120 winding.

Tam


.

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