WM8904
Pre-Production
3. Zobel Networks
The Zobel network shown in Figure 71 is required on HPOUTL, HPOUTR, LINEOUTL and LINEOUTR whenever that output is
enabled. Stability of these ground-referenced outputs across all process corners cannot be guaranteed without the Zobel
network components. (Note that, if any ground-referenced output pin is not required, the zobel network components can be
omitted from the output pin, and the pin can be left floating.) The Zobel network requirement is detailed further in the
applications note WAN_0212 “Class W Headphone Impedance Compensation”.
Zobel networks (C6, C7, C8, C9, R1, R2, R3, R4) should be positioned reasonably close to the WM8904.
4. Microphone Grounding
R7 and R8 can be populated with other values to remove common mode noise on the microphone if required.
PP, Rev 3.3, September 2012
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
