From: "Harry Dellamano"
References: <email@example.com> <3E06A99F.776F9A81@ieee.org> <3E07486E.424879B1@ieee.org> <951O9.102279$4W1.firstname.lastname@example.org> <3E0A3631.4A5C4AC5@ieee.org>
Subject: Re: 87% ... Design requirements are here
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Date: Thu, 26 Dec 2002 20:46:34 GMT
NNTP-Posting-Date: Thu, 26 Dec 2002 15:46:34 EST
"Chris Carlen" wrote in message
> Harry Dellamano wrote:
> >>My, but you Brits are a cheeky bunch. Ok, then. For starters I would
> >>ascertain some basic design information such as the input voltage range
> >>required, the output voltage and current ranges required including
> >>abnormal loads, and efficiency, noise, ripple and EMI requirements. It
> >>seems keeping the magnetics as simple as possible is very important to
> >>Chris, but if it were my project, I would probably go to a true flyback
> >>or a push-pull dc-to-dc converter, depending on what Chris answered
> >>the project requirements.
> > Hi Analog,
> > Cheeky, yes. Brit, no.
> > I agree, we do not have a complete spec from Chris. With that, I
> > can use any topology to get the job done. Hopefully this challenge it
> > to anyone interested. The designs should be submitted to a.b.s.e. on a
> > schematic with critical parts numbers included.
> Here are the constraints I am working with. If you want to work with
> these parameters, then I would be able to contribute to testing. You
> draw, I build and test. Final design should be "open-source" hardware
> (freely offered and able to be copied and distributed as long as
> original contributors' names are included.) If you don't want to do it
> this way, then I can't participate in testing, and will have to make my
> own device on my own, using only conceptual guidance from this forum.
> 11-25VDC input voltage range. 12W maximum output power. 90-350V
> adjustable output voltage. Circuit should still operate down to 8V
> input, but at reduced output power. If you don't like this, then forget
> this 8V input functioning requirement.
> Prefer a boost or flyback topology, isolation of output voltage from
> input is *not* needed, but if a flyback "transformer" rather than plain
> inductor is better for meeting design requirements or simplifying
> circuitry, then use it.
> Regulation and output ripple specs are not critical, you decide. Must
> tolerate short circuited outputs, and open circuited outputs. A default
> minimum load resistor or current sink is Ok, as long as it works over
> the entire 90-350V output and can be disconnected if desired.
> 85% minimum efficiency (default load power dissipation may be included
> in efficiency calcs.) No EMI requirements, for hobby use. If any extra
> circuitry is needed to reduce EMI, it should be easy to and obvious how
> to strip it from the basic system if it is not desired, without breaking
> the design.
> Preferrably use an E19/8/5 standard core size, gapped to whatever is
> needed, using 3C90 or 3C94 material. Max switching frequency 200kHz. I
> have these cores in these materials on hand, and some small 3F3 and 3E5
> toroids on hand if needed for gate drives, but these shouldn't be needed
> for a flyback anyway.
> I will be leaving for Thailand on Dec 29, and will return the week of
> Jan 18. If you can wait until then, I'll start testing when I return.
> Otherwise, do what you want, I'll be interested to see the results when
> I return.
> Good day!
> Christopher R. Carlen
Sounds ok to me. So this is a non isolated dc/dc converter. You even give
us a schedule when it must be completed to make it seem like a real task.
Hopefully we can review all the designs by Jan 18 and have one consolidated
design for you to start testing.
Have a great trip and if this NG is still talking to each other when you
get back we should have a mature design.