Advanced Information
WM8753L
REGISTER
ADDRESS
BIT
LABEL
LD2MO
DEFAULT
DESCRIPTION
R38 (26h)
Mono Mixer
Control (1)
8
7
0
0
Left DAC to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
MM2MO
MM Signal to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
[6:4]
MM2MOVOL
[2:0]
101
(-9dB)
MM Signal to Mono Mixer Volume
000 = +6dB
… (3dB steps)
111 = -15dB
R39 (27h)
Mono Mixer
Control (2)
8
RD2MO
ST2MO
0
0
Right DAC to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
7
Sidetone Signal to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
[6:4]
ST2MOVOL
[2:0]
101
(-9dB)
Sidetone Signal to Mono Mixer
Volume
000 = +6dB
… (3dB steps)
111 = -15dB
3
VXD2MO
0
Voice DAC to Mono Mixer
0 = Disable (Mute)
1 = Enable Path
[2:0]
VXD2MOVOL
[2:0]
101
(-6dB)
Voice Signal to Mono Mixer Volume
000 = +9dB
… (3dB steps)
111 = -12dB
Table 34 Mono Output Mixer Control
ANALOGUE OUTPUTS
LOUT1/ROUT1 OUTPUTS
The LOUT1 and ROUT1 pins can drive a 16Ω or 32Ω headphone or a line output (see Headphone
Output and Line Output sections, respectively). The signal volume on LOUT1 and ROUT1 can be
independently adjusted under software control by writing to LOUT1VOL and ROUT1VOL,
respectively. Note that gains over 0dB may cause clipping if the signal is large. Any gain setting
below 0101111 (-73dB) mutes the output driver. The corresponding output pin remains at the same
DC level (the reference voltage on the VREF pin), so that no click noise is produced when muting or
un-muting.
A zero cross detect on the analogue output may also be enabled when changing the gain setting to
minimize audible clicks and zipper noise as the gain updates. If zero cross is enabled a timeout is
also available to update the gain if a zero cross does not occur. This function may be enabled by
setting TOEN in register R18 (12h).
AI Rev 3.1 June 2004
42
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
