Datasheet

1 mF
1 mF
33 Hm
33 mH
OUTP
OUTN
L1
L2
C2
C3
2.2 mF
2.2 mF
15 Hm
15 mH
OUTP
OUTN
L1
L2
C2
C3
1nF
Ferrite
ChipBead
OUTP
OUTN
Ferrite
ChipBead
1nF
TPA3106D1
www.ti.com SLOS516C –OCTOBER 2007–REVISED AUGUST 2010
When to Use an Output Filter for EMI Suppression
Design the TPA3106D1 without the filter if the traces from amplifier to speaker are short (< 10 cm). Powered
speakers, where the speaker is in the same enclosure as the amplifier, is a typical application for class-D without
a filter.
Most applications require a ferrite bead filter. The ferrite filter reduces EMI around 1 MHz and higher (FCC and
CE only test radiated emissions greater than 30 MHz). When selecting a ferrite bead, choose one with high
impedance at high frequencies, but low impedance at low frequencies.
Use an LC output filter if there are low frequency (<1 MHz) EMI-sensitive circuits and/or there are long wires
from the amplifier to the speaker.
When both an LC filter and a ferrite bead filter are used, the LC filter should be placed as close as possible to
the IC followed by the ferrite bead filter.
Figure 28. Typical LC Output Filter, Cutoff Frequency of 27 kHz, Speaker Impedance = 8 Ω
Figure 29. Typical LC Output Filter, Cutoff Frequency of 27 kHz, Speaker Impedance = 4 Ω
Figure 30. Typical Ferrite Chip Bead Filter (Chip Bead Example: Fair-Rite 2512067007Y3)
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