wm9081 Wolfson Microelectronics plc, wm9081 Datasheet - Page 106

• Manufacturer Part Number: wm9081
• Description: Mono Dac With 2.6w Class Ab/d Speaker Driver, Dynamic Range Controller And Retune Mobile Parametric Equalizer
• Manufacturer: Wolfson Microelectronics plc

WM9081
PCB LAYOUT CONSIDERATIONS
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Figure 68 Speaker Equivalent Circuit
Notes
1.
The efficiency of the speaker driver is affected by the series resistance between the WM9081 and
the speaker (e.g. inductor ESR) as shown in Figure 69. This resistance should be as low as possible
to maximise efficiency.
Figure 69 Speaker Connection Losses
The distance between the WM9081 and the speaker should be kept to a minimum to reduce series
resistance, and also to reduce EMI. Further reductions in EMI can be achieved by additional passive
filtering and/or shielding as shown in Figure 70. When additional passive filtering is used, low ESR
components should be chosen to minimise series resistance between the WM9081 and the speaker,
maximising efficiency.
For further information on speaker selection, refer to the application note WAN_0200
‘Speaker Selection for Class D output drivers’.
PP, Rev 3.0, April 2009
Pre-Production
106