wm9081 Wolfson Microelectronics plc, wm9081 Datasheet - Page 39

• Manufacturer Part Number: wm9081
• Description: Mono Dac With 2.6w Class Ab/d Speaker Driver, Dynamic Range Controller And Retune Mobile Parametric Equalizer
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
RETUNE MOBILE PARAMETRIC EQUALIZER (EQ)
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The ReTune Mobile Parametric EQ is a circuit which can be enabled in the DAC digital signal path.
The function of the EQ is to adjust the frequency characteristic of the output in order to compensate
for unwanted frequency characteristics in the loudspeaker (or other output transducer). It can also be
used to tailor the response according to user preferences, for example to accentuate or attenuate
specific frequency bands to emulate different sound profiles or environments e.g. concert hall, rock
etc.
The EQ is enabled as shown in Table 18.
Table 18 ReTune Mobile Parametric EQ Enable
The EQ can be configured to operate in two modes - “Default” mode or “ReTune Mobile” mode.
DEFAULT MODE (5-BAND PARAMETRIC EQ)
In default mode, the cut-off / centre frequencies are fixed as per Table 19. The filter bandwidths are
also fixed in default mode. The gain of the individual bands (-12dB to +12dB) can be controlled as
described in Table 20. A full definition of the EQ Gain settings is provided in Table 21.
Note that the cut-off / centre frequencies noted in Table 19 are applicable to a DAC Sample Rate of
48kHz. When using other sample rates, these frequencies will be scaled in proportion to the selected
sample rate.
Table 19 EQ Band Cut-off / Centre Frequencies
R42 (2Ah)
EQ1
R42 (2Ah)
EQ1
REGISTER
REGISTER
ADDRESS
ADDRESS
EQ BAND
1
2
3
4
5
15:11
10:6
BIT
BIT
5:1
0
EQ_ENA
EQ_B1_GAIN
[4:0]
EQ_B2_GAIN
[4:0]
EQ_B3_GAIN
[4:0]
LABEL
LABEL
CUT-OFF/CENTRE
FREQUENCY
2400 Hz
6900 Hz
100 Hz
300 Hz
875 Hz
DEFAULT
0_0000
0_0000
0_0000
DEFAULT
0
EQ Band 1 Gain
00000 = -12dB
00001 = -11dB
….
11000 = +12dB
EQ Band 2 Gain
00000 = -12dB
00001 = -11dB
….
11000 = +12dB
EQ Band 3 Gain
00000 = -12dB
EQ Enable
0 = Disabled
1 = Enabled
DESCRIPTION
DESCRIPTION
PP, Rev 3.0, April 2009
WM9081
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