wm8903 Wolfson Microelectronics plc, wm8903 Datasheet - Page 66

• Manufacturer Part Number: wm8903
• Description: Ultra Low Power Codec For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

WM8903
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EXTERNAL COMPONENTS FOR GROUND-REFERENCED OUTPUTS
In the case of the ground referenced outputs HPOUTL, HPOUTR, LINEOUTL and LINEOUTR, it is
recommended to connect a zobel network to the audio output pins for best audio performance in all
applications. The components of the zobel network have the effect of dampening high frequency
oscillations or instabilities that can arise outside the audio band under certain conditions. Possible
sources of these instabilities include the inductive load of a headphone coil or an active load in the
form of an external line amplifier. The capacitance of lengthy cables or PCB tracks can also lead to
amplifier instability. The zobel network should comprise a 20Ω resistor and 0.1μF capacitor in series
with each other, as illustrated in Figure 34.
Figure 34 Zobel Network Components for HPOUTL, HPOUTR, LINEOUTL and LINEOUTR
It is recommended to include these components for best audio quality and amplifier stability in all
cases.
The differential line outputs LOP/LON and ROP/RON would, typically, be connected to differential
line drivers such as the WM9001 speaker driver. In such applications, a zobel network is not required
on these differential line outputs.
Output
20
0.1uF
PP, Rev 3.1, August 2009
Load
Pre-Production
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