WM9082 WOLFSON [Wolfson Microelectronics plc], WM9082 Datasheet - Page 18

• Manufacturer Part Number: WM9082
• Description: PDM Input Mono 3W Class D Speaker Driver
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

WM9082
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Figure 4 Speaker Connection Losses
The Class D output requires external filtering in order to recreate the audio signal. This may be
implemented using a 2
internal inductance provides the required filter response. An LC filter should be used if the
loudspeaker characteristics are unknown or unsuitable, or if the length of the loudspeaker connection
is likely to lead to EMI problems.
A suitable LC filter implementation is illustrated in Figure 5.
Figure 5 Class D Output Filter Components
A simple equivalent circuit of a loudspeaker consists of a serially connected resistor and inductor, as
shown in Figure 6. This circuit provides a low pass filter for the speaker output. If the loudspeaker
characteristics are suitable, then the loudspeaker itself can be used in place of the filter components
described earlier. This is known as ‘filterless’ operation.
Figure 6 Speaker Equivalent Circuit for Filterless Operation
nd
order LC filter, or else may be achieved by using a loudspeaker whose
PD, August 2012, Rev 4.1
Production Data
18