WM8750L
Production Data
OUTPUT MIXERS
The WM8750L provides the option to mix the DAC output signal with analogue line-in signals from the
LINPUT1/2/3, RINPUT1/2/3 pins or a mono differential input (LINPUT1 – RINPUT1) or (LINPUT2 –
RINPUT2), selected by DS (see Table 5) . 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].
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R34 (22h)
LMIXSEL
Left Input Selection for Output Mix
000 = LINPUT1
2:0
000
Left Mixer (1)
001 = LINPUT2
010 = LINPUT3
011 = Left ADC Input (after PGA /
MICBOOST)
100 = Differential input
Right Input Selection for Output Mix
000 = RINPUT1
R36 (24h)
RMIXSEL
2:0
000
Right Mixer
(1)
001 = RINPUT2
010 = RINPUT3
011 = Right ADC Input (after PGA /
MICBOOST)
100 = Differential input
Table 21 Output Mixer Signal Selection
REGISTER
ADDRESS
BIT
LABEL
LD2LO
DEFAULT
DESCRIPTION
R34 (22h)
Left DAC to Left Mixer
0 = Disable (Mute)
1 = Enable Path
8
0
Left Mixer
Control (1)
LI2LO
LMIXSEL Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
7
0
LI2LOVOL
[2:0]
LMIXSEL Signal to Left Mixer Volume
000 = +6dB
6:4
101
(-9dB)
… (3dB steps)
111 = -15dB
R35 (23h)
RD2LO
RI2LO
Right DAC to Left Mixer
0 = Disable (Mute)
1 = Enable Path
8
7
0
0
Left Mixer
Control (2)
RMIXSEL Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
RI2LOVOL
[2:0]
RMIXSEL Signal to Left Mixer Volume
000 = +6dB
6:4
101
(-9dB)
… (3dB steps)
111 = -15dB
Table 22 Left Output Mixer Control
PD, Rev 4.4, August 2012
32
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
