Specifications

Chapter 5 – Power Supplies for PL Smart Transceivers
178 PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Boo
k
Figure 5.16 Optional Switching Power Supply Filter
The C-band version of this filter has the attenuation characteristics shown in Figure 5.17, when connected to a 50
Ω
mains network. The characteristics of the A-band version of the filter into a 50
Ω network are shown in Figure 5.18.
If the power supply noise drops by less than the values indicated in the graph when the filter is added, it is likely due
to parasitic coupling between the two inductors. If this occurs, filtering of the level shown in Figures 5.17 or 5.18 can
usually be accomplished by adjusting the relative location and orientation of the inductors (orthogonal orientation
typically reduces inductor coupling). Alternately, shielded or toroidal inductors can be used to reduce coupling.