wm8941 Wolfson Microelectronics plc, wm8941 Datasheet - Page 48

• Manufacturer Part Number: wm8941
• Description: Mono Codec With Speaker Driver And Video Buffer
• Manufacturer: Wolfson Microelectronics plc

WM8941
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Table 37 Mono Mixer Control
ENABLING THE OUTPUTS
Table 38 Output Stages Power Management Control
UNUSED ANALOGUE INPUTS/OUTPUTS
Each analogue output of the WM8941 can be separately enabled or disabled. The analogue mixer
associated with each output has a separate enable. All outputs are disabled by default. To save
power, unused parts of the WM8941 should remain disabled.
Outputs can be enabled at any time, but it is not recommended to do so when BUFIO is disabled
(BUFIOEN=0), as this may cause pop noise (see “POP Minimisation” section).
Whenever an analogue input/output is disabled, it remains connected to AVDD/2 through a resistor.
This helps to prevent pop noise when the output is re-enabled. The resistance between the voltage
buffer and the output pins can be controlled using the VROI control bit. The default impedance is
low, so that any capacitors on the outputs can charge up quickly at start-up. If a high impedance is
desired for disabled outputs, VROI can then be set to 1, increasing the resistance to about 30kΩ.
R56
Mono mixer
control
R1
Power
management 1
R3
Power
management 3
Note: All “Enable” bits are 1 = ON, 0 = OFF
REGISTER
ADDRESS
REGISTER
ADDRESS
3
2
7
6
5
3
2
BIT
BIT
7
6
2
1
0
MONOEN
BIASEN
BUFIOEN
SPKNEN
SPKPEN
MONOMIXEN 0
SPKMIXEN
MONOATTN
MONOMUTE
AUX2MONO
BYP2MONO
DAC2MONO
LABEL
LABEL
0
0
0
0
0
0
DEFAULT
0
DEFAULT
0
0
0
0
Analogue amplifiers bias enable
VMID buffer enable
MONOOUT enable
SPKOUTN enable
SPKOUTP enable
Mono mixer enable
Speaker Mixer enable
Attenuation control for bypass path
(output of input boost stage) to mono
mixer input
1 0 = 0dB
0 1 = -10dB
0=No mute
1=Output muted. During mute the mono
output will output VMID which can be
used as a DC reference for a
headphone out.
Output of Auxillary amplifier to mono
mixer input:
0 = not selected
1 = selected
Bypass path (output of input boost
stage) to mono mixer input
0 = non selected
1 = selected
Output of DAC to mono mixer input
0 = not selected
1 = selected
DESCRIPTION
DESCRIPTION
PD, Rev 4.0, August 2008
Production Data
48