22
TPA3116D2
,
TPA3118D2
,
TPA3130D2
SLOS708G –APRIL 2012–REVISED DECEMBER 2017
www.ti.com
Product Folder Links: TPA3116D2 TPA3118D2 TPA3130D2
Submit Documentation Feedback Copyright © 2012–2017, Texas Instruments Incorporated
Figure 34. TPA311xD2 Radiated Emissions
7.3.15 When to Use an Output Filter for EMI Suppression
The TPA3116D2 has been tested with a simple ferrite bead filter for a variety of applications including long
speaker wires up to 125 cm and high power. The TPA3116D2 EVM passes FCC class-B specifications under
these conditions using twisted speaker wires. The size and type of ferrite bead can be selected to meet
application requirements. Also, the filter capacitor can be increased if necessary with some impact on efficiency.
There may be a few circuit instances where it is necessary to add a complete LC reconstruction filter. These
circumstances might occur if there are nearby circuits which are sensitive to noise. In these cases a classic
second order Butterworth filter similar to those shown in the figures below can be used.
Some systems have little power supply decoupling from the AC line but are also subject to line conducted
interference (LCI) regulations. These include systems powered by "wall warts" and "power bricks." In these
cases, LC reconstruction filters can be the lowest cost means to pass LCI tests. Common mode chokes using
low frequency ferrite material can also be effective at preventing line conducted interference.
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