Hi Brian,
One needs to be a little careful with caps on the output. I have seen
many cases where they form a resonant circuit with the inductance of
wires connected to the supply and make the problem even worse.
How about a puzzle? How do you make a non-resonant capacitor using three
components?
Doug
University of Oxford Tutor
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom
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On 12/1/14 12:30 PM, Brian Oconnell wrote:
Have seen somewhat useable app notes by Vicor, Calex, Interpoint for dealing
with DC/DC switching noise.
For DC stuff, typically recommend caps, as there can be secondary affects (be
careful if you must meet LPS/Class 2). If no spacing or thermal issues, a tight
can or some level of close-in shielding referenced to secondary can be best
solution if input not referenced to output.
Brian
-----Original Message-----
From: Amund Westin [mailto:[email protected]]
Sent: Monday, December 01, 2014 11:48 AM
To: [email protected]
Subject: [PSES] Noisy DC / DC converter
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.
Any other "tricks" for EMI suppression of DC / DC converters?
#Amund
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