wm8988 Wolfson Microelectronics plc, wm8988 Datasheet - Page 29

• Manufacturer Part Number: wm8988
• Description: Stereo Codec For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

Production Data
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OUTPUT MIXERS
The WM8988 provides the option to mix the DAC output signal with analogue line-in signals from the
LINPUT1/2, RINPUT1/2 pins or a mono differential input (LINPUT1 – RINPUT1) or (LINPUT2 –
RINPUT2), selected by DS (see Table 6) . The level of the mixed-in signals can be controlled with
PGAs (Programmable Gain Amplifiers).
The mono mixer is designed to allow a number of signal combinations to be mixed, including the
possibility of mixing both the right and left channels together to produce a mono output. To prevent
overloading of the mixer when full-scale DAC left and right signals are input, the mixer inputs from
the DAC outputs each have a fixed gain of -6dB. The bypass path inputs to the mono mixer have
variable gain as determined by R38/R39 bits [6:4].
Table 21 Output Mixer Signal Selection
Table 22 Left Output Mixer Control
R34 (22h)
Left Mixer (1)
R36 (24h)
Right Mixer
(1)
R34 (22h)
Left Mixer
Control (1)
R35 (23h)
Left Mixer
Control (2)
REGISTER
REGISTER
ADDRESS
ADDRESS
2:0
2:0
8
7
6:4
8
7
6:4
BIT
BIT
LMIXSEL
RMIXSEL
LD2LO
LI2LO
LI2LOVOL
[2:0]
RD2LO
RI2LO
RI2LOVOL
[2:0]
LABEL
LABEL
000
000
0
0
101
(-9dB)
0
0
101
(-9dB)
DEFAULT
DEFAULT
Left DAC to Left Mixer
0 = Disable (Mute)
1 = Enable Path
LMIXSEL Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
LMIXSEL Signal to Left Mixer Volume
000 = +6dB
… (3dB steps)
111 = -15dB
Right DAC to Left Mixer
0 = Disable (Mute)
1 = Enable Path
RMIXSEL Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
RMIXSEL Signal to Left Mixer Volume
000 = +6dB
… (3dB steps)
111 = -15dB
Left Input Selection for Output Mix
000 = LINPUT1
001 = LINPUT2
010 = Reserved
011 = Left ADC Input (after PGA /
100 = Differential input
Right Input Selection for Output Mix
000 = RINPUT1
001 = RINPUT2
010 = Reserved
011 = Right ADC Input (after PGA /
100 = Differential input
MICBOOST)
MICBOOST)
DESCRIPTION
DESCRIPTION
PD, Rev 4.0, October 2008
WM8988
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