[time-nuts] Need help with transformer core

Attila Kinali attila at kinali.ch
Sun Aug 31 11:12:04 EDT 2014


Hoi Bert,

On Sun, 31 Aug 2014 07:15:02 -0400 (EDT)
Bert Kehren via time-nuts <time-nuts at febo.com> wrote:

> Any opinion or observation on Mean Well's SD series, they are a key  
> component on most of our projects.

I never had the pleasure to measure any of the Mean Well DC/DC converters.
Looking at their spec, they seem decent enough. The ripple and load
regulation specs are not exactly time-nut class, but not unheard of
for this kind of brick, isolating DC/DC converters. Also a nice feature
is the CE marking, resp the EMC emission specs, which a lot of cheaper
devices do not have. Unfortunately, they do not mention which class
of the EN55022 they comply to. It's probably Class B, but not necesarily. [1]
What i'm missing is a specification of the switching frequency, that would
help to guide the filter needed at the output. But i'd assume it's
something in the range of 100kHz-500kHz, definitly less than 1MHz at
these power ratings.

Such brick converters are usually used as a first stage converter to
power a complete system from some industrial or telecom power rail.
As such, they are meant to have a second stage regulator infront of
the electronics (or electronics that can cope with the ripples and
flucutation of the power rails, like slow digital logic).
Ie. i recommend to use another, specialized DC/DC converter or LDO
infront of your electronics, to keep the power more stable and have
less ripple.

As for use with an FE-5680A, i guess these DC/DC converters are good
enough, as the FE-5680A has its own internal regulator.

HTH

			Attila Kinali



[1] A little warning here. The normal way how such devices pass the
EMC/EMI tests is by constructing a still realistic circuitry around
it, that modifies the devices behaviour enough that any non-compliance
is mitigated. Unless you measure these devices with a realistic model
of your system, or the system itself, you cannot be sure that the
DC/DC converter still passes the EMC regulations.


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