EVL6563H-100W View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'EVL6563H-100W' PDF : 31 Pages View PDF
AN3118
EMI filtering and conducted EMI pre-compliance measurements
7
EMI filtering and conducted EMI pre-compliance
measurements
The following figures show the measurement in average mode of the conducted noise at full
load and nominal mains voltages for both mains lines. The limits shown in the diagrams are
EN55022 class-B which is the most popular regulation for domestic equipment using a two-
wire mains connection.
It is worth remembering that typically a PFC produces a significant differential mode noise
with respect to other topologies. In case an additional margin, with respect to the limits, is
needed, increasing the differential attenuation by increasing the across the line (X)
capacitors or the C4 capacitor after the rectifier bridge is suggested. Sometimes a
differential mode coil connected as a pi-filter placed after, between the bridge rectifier and
the boost stage, is more effective and cheaper than increasing the size of the common
mode filter coil that would only filter the differential mode noise by the leakage inductance
between the two windings.
To recognize if the circuit is affected by common mode or differential mode noise, it is
sufficient to compare the spectrum of phase and neutral line measurements; if the two
measurements are very similar, the noise is almost totally common mode. If there is a
significant difference between the two measurement spectrums, their difference represents
the amount of differential mode noise. Of course to get a reliable comparison the two
measurements must be done in the same conditions.
Because the differential mode produces common mode noise by the magnetic field induced
by the current, decreasing the differential mode consequently limits the second one.
As visible in the diagrams, in all test conditions there is at least a 6dB margin of the
measurements with respect to the limits. The measurements have been done in AVG
detection to evaluate the benefit of the jittering effect of the TM control.
Figure 40. EVL6563H-250W CE AVG
Figure 41. EVL6563H-250W CE AVG
measurement at 115 Vac-60 Hz - full
measurement at 115 Vac-60 Hz - full
load - phase wire
load - neutral wire
Doc ID 16847 Rev 2
27/31
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