WM8955BL
Production Data
LINE INPUTS AND OUTPUT MIXERS
The WM8955BL provides the option to mix the DAC output signal with analogue line-in signals from
the LINEINL, LINEINR and MONOIN+ and MONOIN- pins. The level of the mixed-in signals can be
controlled with PGAs (Programmable Gain Amplifiers).
LINEINL, LINEINR, MONOIN+ and MONOIN- are high impedance, low capacitance AC coupled
analogue inputs. They are biased internally to the reference voltage VREF. Whenever these inputs
are muted or the device placed into standby mode, the inputs remain biased to VREF using special
anti-thump circuitry. This reduces any audible clicks that may otherwise be heard when re-activating
the inputs.
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
LD2LO
DEFAULT
DESCRIPTION
Left DAC to Left Mixer
R34 (22h)
8
0
0
Left Mixer (1)
0 = Disable (Mute)
1 = Enable Path
7
LI2LO
LINEINL Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
LI2LOVOL
101
LINEINL Signal to Left Mixer Volume
000 = +6dB
(-9dB)
… (3dB steps)
111 = -15dB
R35 (23h)
8
RD2LO
0
0
Right DAC to Left Mixer
0 = Disable (Mute)
1 = Enable Path
Left Mixer (2)
7
MI2LO
MONOIN Signal to Left Mixer
0 = Disable (Mute)
1 = Enable Path
6:4
MI2LOVOL
101
MONOIN Signal to Left Mixer Volume
000 = +6dB
(-9dB)
… (3dB steps)
111 = -15dB
Table 7 Left Output Mixer Control
PD Rev 4.1 February 2007
20
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
