wm8903 Wolfson Microelectronics plc, wm8903 Datasheet - Page 54

• Manufacturer Part Number: wm8903
• Description: Ultra Low Power Codec For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

WM8903
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DAC MONO MIX
A DAC digital mono-mix mode can be enabled using the DAC_MONO register bit. This mono mix will
be output on whichever DAC is enabled. To prevent clipping, a -6dB attenuation is automatically
applied to the mono mix. Only one DAC must be enabled in order to use this function.
Table 30 DAC Mono Mix
DAC DE-EMPHASIS
Digital de-emphasis can be applied to the DAC playback data (e.g. when the data comes from a CD
with pre-emphasis used in the recording). De-emphasis filtering is available for sample rates of
48kHz, 44.1kHz and 32kHz. See “Digital Filter Characteristics” for details of de-emphasis filter
characteristics.
Table 31 DAC De-Emphasis Control
DAC SLOPING STOPBAND FILTER
Two DAC filter types are available, selected by the register bit DAC_SB_FILT. When operating at
sample rates ≤ 2 4kHz (e.g. during voice communication) it is recommended that the sloping stopband
filter type is selected (DAC_SB_FILT=1) to reduce out-of-band noise which can be audible at low
DAC sample rates. See “Digital Filter Characteristics” for details of DAC filter characteristics.
Table 32 DAC Sloping Stopband Filter
R33 (21h)
DAC Digital 1
R33 (21h)
DAC Digital 1
R33 (21h)
DAC Digital 1
REGISTER
REGISTER
REGISTER
ADDRESS
ADDRESS
ADDRESS
2:1
BIT
BIT
BIT
12
11
DAC_MONO
DAC_SB_FILT
DEEMPH [1:0]
LABEL
LABEL
LABEL
DEFAULT
DEFAULT
DEFAULT
00
0
0
DAC Mono Mix
0 = Stereo
1 = Mono (Mono mix output on
enabled DAC)
Selects DAC filter characteristics
0 = Normal mode
1 = Sloping stopband mode
(recommended when fs ≤ 24kHz)
DAC De-Emphasis Control
00 = No de-emphasis
01 = 32kHz sample rate
10 = 44.1kHz sample rate
11 = 48kHz sample rate
PP, Rev 3.1, August 2009
DESCRIPTION
DESCRIPTION
DESCRIPTION
Pre-Production
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