Dear Mike Reagan,
"Mike Reagan" <[EMAIL PROTECTED]> on 2001-06-13 10:54:57 AM wrote:
> While a Spiraled trace to simulate an inductor might be a desirable
> accomplishment, I try to convince engineers to stay away from this type of
> design.
Yes, I agree that trying to build inductors, capacitors and resistors out of
traces on a circuit board is usually more trouble than it's worth. In my case, I
finally got enough documentation to prove that PWB traces varied in resistance
far more than the 1% we wanted in our current-sense resistor. (Mostly due to
variations in the tin plating over copper, I hear).
Talking about transformers, I've been hearing a lot about ``piezoelectric
transformers''. I have a couple of catalogs sitting on my desk that I can buy an
entire module that contains a piezoelectric transformers, but I've searched and
searched and have failed to find anyone willing to sell me *just* the
transformers and quote a price on it.
Putting spiral traces to simulate inductors and transformers seems to be getting
more popular, *if* you put the appropriate core around it. (But I can just hear
management now, asking if we can leave out that ``added cost''). Here's some
related links:
``Designing with Planar Ferrite Cores'' by Mark A. Swihart,
http://www.mag-inc.com/Designing%20with%20Planar%20Ferrite%20Cores%20.pdf
Using Planar Transformers in Low-Profile Switch-Mode Power Supplies
http://www.signaltransformer.com/signal/planar/planar.cfm
http://www.neosid.de/planartr1.htm
has photographs of planar transformers/inductors
Planar transformers contribute to miniaturization
http://www.electroniccomponents.globalsources.com/MAGAZINE/EC/0106/PLANTRA.HTM
Planar Magnetics
http://www.nmrc.ie/projects/pei/ipm-publications.html
``The benefits of planar magnetics'' by Professor Sam Ben-Yaakov
http://www.paytongroup.com/paytonamerica/bp1_planar_magnetics.html
--
David Cary
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