TPA2035D1 Datasheet, PDF (15/20 Pages) Texas Instruments – 2.75-W FIXED GAIN MONO FILTER-FREE CLASS-D AUDIO POWER AMPLIFIER

TPA2035D1
www.ti.com ................................................................................................................................................................................................ SLOS562 – AUGUST 2008
WHEN TO USE AN OUTPUT FILTER
Design the TPA2035D1 without an output filter if the traces from the amplifier to the speaker are short. Wireless
handsets and PDAs are great applications for this class-D amplifier to be used without an output filter.
The TPA2035D1 passed FCC- and CE-radiated emissions testing with no shielding with speaker trace wires 100
mm long or less. For longer speaker trace wires, a ferrite bead can often be used in the design if failing radiated
emissions testing without an LC filter; and, the frequency-sensitive circuit is greater than 1 MHz. If choosing a
ferrite bead, choose one with high impedance at high frequencies, but very low impedance at low frequencies.
The selection must also take into account the currents flowing through the ferrite bead. Ferrites can begin to
loose effectiveness at much lower than rated current values. See the EVM User's Guide (SLOU237) for
components used successfully by TI.
Figure 34 shows a typical ferrite-bead output filter.
Ferrite
Chip Bead
V_O−
Ferrite
Chip Bead
V_O+
1 nF
1 nF
Figure 34. Typical Ferrite Chip Bead Filter
Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): TPA2035D1
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