In message <[email protected]>, dated
Mon, 1 Dec 2014, Amund Westin <[email protected]> writes:
Got a DC / DC converter in an ITE.
From a radiated emission plot, I can see lot of spikes with spacing
330kHz in the region 30-80MHz. The DC / DC converter datasheet tells
that the switching frequency is 330kHz. No suppression components
around the converter. I assume a common mode choke could block some on
the noise, so it does not enter the power supply cable, which may act
as an antenna in this case.
Presumably, with a 330 kHz switching frequency, it's a very small box,
so the cable is the antenna. But the emissions may not be all
common-mode. Any differential-mode emissions can and will be converted
to common-mode at any discontinuity, maybe even a sharp bend, in the
cable. So look for differential-mode as well.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
When I turn my back on the sun, it's to look for a rainbow
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
-
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