DC Power and Noise
Many of the Kemo products are available with DC power input
for portable applications. Typically 9 - 30 V DC power input, where 12 V or 24 V DC is
available from batteries or a vehicle supply.
Most DC powered units use DC - DC converters, these are switching devices and
they generate high frequency switching energy. Depending on the devices used and
their type the level of this energy varies, but in low quality units it can be several volts
on a typical unsmoothed 15 volt supply. The energy is typically a high speed
switching pulse of several MHz frequency content which repeats at about 100 kHz.
This energy will get into most
signal circuits as some of the content is radiated.
We use a number of techniques to minimise this noise. Good quality DC-DC
converters from a reputable and stable manufacturer. Then we use the best
practice possible in our circuit board layouts, wiring, and power filtering
around the DC-DC converters. Typically we attenuate any DC-DC power noise by
a factor of over 50. However some of this energy still gets into the signal
paths, and is seen as high frequency 'noise'. So if you require a portable
system, there may be a higher noise level than with a
'mains' powered unit. Our experience is that in low frequency (<20kHz) systems
with signal levels above about 100mV DC-DC related issues are not a problem.
IF in doubt - contact us to discuss your application, we have probably done
it before in our past.
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Unit 1, Dene Yard,
Green Street Green Road
Dartford, Kent,
DA2 8DH.
United Kingdom
Tel: +44 (0)1474 705168
Fax: +44 (0)1474 705366
email: uk@kemo.com |
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5 Northbrook Way
Greenville,
SC 29615.
U.S.A.
Tel: (864) 297 2522
Fax: (864) 675 1530
email: usa@kemo.com |
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