wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 96

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

WM8400
w
Figure 43 Stereo Line Out (C)
DISABLED OUTPUTS
Whenever an analogue output is disabled, it remains connected to VREF through a resistor. This
helps to prevent pop noise when the output is re-enabled. The resistance between VREF and each
output can be controlled using register bit VROI. By default, a high resistance is used - 20kΩ for
Headphone outputs (LOUT, ROUT, OUT3 and OUT4) and 10kΩ for Line outputs (LON, LOP, RON
and ROP). If a low impedance is desired for disabled outputs, VROI can then be set to 1, decreasing
the resistance to about 500Ω in all cases.
Note that a disabled output may be used as a common ground connection for a capless headphone
output as described earlier.
Table 60 Disabled Outputs to VREF Resistance
R55 (37h)
Additional
Control
REGISTER
ADDRESS
BIT
0
VROI
LABEL
DEFAULT
Figure 44 Stereo Differential Line Out
0
VREF to Analogue Output Resistance
(Disabled Outputs)
0 = 20kΩ (Headphone) or 10kΩ (Line
Out) from buffered VMID to output
1 = 500Ω from buffered VMID to output
DESCRIPTION
PP, April 2009, Rev 3.0
Pre-Production
96