[time-nuts] Need help with transformer core

EWKehren at aol.com EWKehren at aol.com
Sun Aug 31 11:29:08 EDT 2014


Thanks for the reply in all applications the DC DC converter is used for  
isolation and followed by linear regulators. In critical stages like dual 
mixer  two stages.
Bert 
 
 
In a message dated 8/31/2014 11:12:18 A.M. Eastern Daylight Time,  
attila at kinali.ch writes:

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.


--  
I pity people who can't find laughter or at least some bit of amusement  in
the little doings of the day. I believe I could find something  ridiculous
even in the saddest moment, if necessary. It has nothing to do  with being
superficial. It's a matter of joy in life.
-- Sophie  Scholl



More information about the time-nuts mailing list