WM8731 / WM8731L
Production Data
The recommended external components required to complete the application are shown in Figure 22.
HPOUT
C1
AGND
R1
AGND
Figure 22 Headphone Output Application Drawing
Recommended values are C1 = 220uF (10V electrolytic), R1 = 47k
C1 forms a DC blocking capacitor to isolate the dc of the HPOUT from the headphones. R1 form a
pull down resistor to discharge C1 to prevent the voltage at the connection to the headphones from
rising to a level that may damage the headphones.
BYPASS MODE
The WM8731/L includes a bypass mode whereby analogue line inputs are routed directly to the
analogue line outputs and headphone outputs. The scheme for this is in Figure 23.
LINEIN
12.5K
SIDETONE (OFF)
BYPASS (ON)
VMID
FROM
LINE
INPUTS
DACSEL (OFF)
FROM
DAC
LINEOUT
VMID
HPOUT
VMID
Figure 23 Signal Routing in Bypass Mode
PD, Rev 4.8, April 2009
32
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
