T
treez
Guest
Page 31 of AN5 by power.com states that a good way to reduce conducted emissions in an offline SMPS
that is in a plastic enclosure is to put a metal plate under the enclosure...
this metal plate being the same size as the power supply PCB. It says that this plate should be
connected to the incoming Earth ground.
I would have thought that this procedure would result in worse common mode emissions?
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Page 29 of AN15 states that we can view only the common mode conducted emissions of an offline SMPS by
use of two splitters (an in -phase splitter, and an out-of-phase splitter). Does anyone have such a conducted emissions
scan available to share here? (ie a conducted scan of an offline smps with the splitters attached)
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Page 3 of AN15 shows a conducted EMC emissions setup for an offline SMPS (figure 6). It says that 6 foot cables
should be used between the unit under test and the LISN, and the UUT and the load....but in the picture they
dont look like 6 foot cables, they look much shorter...can this be "six foot" be right?
Also, it seems to be saying that the table is up against a vertical "reference plane" which is 2m by 2m. Presumably this
reference plane is just a floating piece of metal sheet? The LISN must be bonded to this metal plane. I thought that the LISN
should be right up against the reference plane, so that the LISN's connection to the reference plane can be as short as possible?
Also, i thought that the table should have a metal sheet beneath it aswell as the one at the end of it?
Also, where does the spectrum analyser go in this setup?..presumably it connects to the LISN via a coaxial cable..and the specturm analyser is
at least 2 metres away from the unit under test?
Also, since the test setup in figure 6 is not as complete as in an accredited test house, the conducted EMC scans will be discrepant.
What will be the main nature of this discrepancy?
AN15
https://ac-dc.power.com/design-supp...on-notes/an-15-topswitch-power-supply-design/
that is in a plastic enclosure is to put a metal plate under the enclosure...
this metal plate being the same size as the power supply PCB. It says that this plate should be
connected to the incoming Earth ground.
I would have thought that this procedure would result in worse common mode emissions?
----------------------------------------------------------------------------------------------------------
Page 29 of AN15 states that we can view only the common mode conducted emissions of an offline SMPS by
use of two splitters (an in -phase splitter, and an out-of-phase splitter). Does anyone have such a conducted emissions
scan available to share here? (ie a conducted scan of an offline smps with the splitters attached)
----------------------------------------------------------------------------------------------------------
Page 3 of AN15 shows a conducted EMC emissions setup for an offline SMPS (figure 6). It says that 6 foot cables
should be used between the unit under test and the LISN, and the UUT and the load....but in the picture they
dont look like 6 foot cables, they look much shorter...can this be "six foot" be right?
Also, it seems to be saying that the table is up against a vertical "reference plane" which is 2m by 2m. Presumably this
reference plane is just a floating piece of metal sheet? The LISN must be bonded to this metal plane. I thought that the LISN
should be right up against the reference plane, so that the LISN's connection to the reference plane can be as short as possible?
Also, i thought that the table should have a metal sheet beneath it aswell as the one at the end of it?
Also, where does the spectrum analyser go in this setup?..presumably it connects to the LISN via a coaxial cable..and the specturm analyser is
at least 2 metres away from the unit under test?
Also, since the test setup in figure 6 is not as complete as in an accredited test house, the conducted EMC scans will be discrepant.
What will be the main nature of this discrepancy?
AN15
https://ac-dc.power.com/design-supp...on-notes/an-15-topswitch-power-supply-design/