WM8731 / WM8731L
Production Data
The software control for the line outputs is shown in Table 8.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
0000100
Bypass Switch
1 = Enable Bypass
3
BYPASS
1
Analogue
Audio Path
Control
0 = Disable Bypass
DAC Select
4
5
DACSEL
0
0
1 = Select DAC
0 = Don’t select DAC
Side Tone Switch
1 = Enable SideTone
0 = Disable Side Tone
SIDETONE
Table 8 Output Software Control
The recommended external components are shown in Figure 20.
R2
LINEOUT
C1
R1
AGND
AGND
Figure 20 Line Outputs Application Drawing
Recommended values are C1 = 10F, R1 = 47k, R2 = 100 Ω.
C1 forms a DC blocking capacitor to the line outputs. R1 prevents the output voltage from drifting so
protecting equipment connected to the line output. R2 forms a de-coupling resistor preventing
abnormal loads from disturbing the device. Note that poor choice of dielectric material for C1 can
have dramatic effects on the measured signal distortion at the output
HEADPHONE AMPLIFIER
The WM8731/L has a stereo headphone output available on LHPOUT and RHPOUT. The output is
designed specifically for driving 16 or 32 Ω headphones with maximum efficiency and low power
consumption. The headphone output includes a high quality volume level adjustment and mute
function.
PD, Rev 4.9, October 2012
29
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
