Datasheet

FCCBLimit
PeakdB
70
60
50
40
30
20
20
0
30M
230M 430M
630M 830M
NationalTechnicalSystems,PlanoTX
RadiatedEmissions30MHz-1000MHz
FCCB
f-Frequency-Hz
LimitLevel-dB( V/m)m
TPA3100D2
SLOS469F –OCTOBER 2005–REVISED AUGUST 2010 www.ti.com
Using the LC filter in Figure 27, the TPA3100D2 EMI EVM passed the FCC Part 15 Class B radiated emissions
with 21-inch speaker wires. Quasi-peak measurements were taken for the 4 standard test configurations, and the
TPA3100D2 EVM passed with at least 17-dB margin. A plot of the peak measurement for the horizontal rear
configuration is shown in Figure 30.
Figure 30. Radiated Emissions Prescan 30 MHz - 1000 MHz
Inductors used in LC filters must be chosen carefully. A significant change in inductance at the peak output
current of the TPA3100D2 will cause increased distortion. The change of inductance at currents up to the peak
output current must be less than 0.1 mH per amp to avoid this distortion. Also note that smaller inductors than 33
mH may cause an increase in distortion above what is shown in the preceding graphs of THD versus frequency
and output power.
Capacitors used in LC filters must also be chosen carefully. A significant change in capacitance at the peak
output voltage of the TPA3100D2 will cause increased distortion. LC filter capacitors should have DC voltage
ratings at least twice the peak application voltage (the power supply voltage) and should be made of X5R or
better material. In all cases avoid using capacitors with loose temperature ratings, like Y5V.
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