WM8750BL Datasheet, PDF (28/59 Pages) Wolfson Microelectronics plc – Stereo CODEC for Portable Audio Applications

WM8750BL
Pre-Production
GRAPHIC EQUALISER
The WM8750BL has a digital graphic equaliser and adaptive bass boost function. This function
operates on digital audio data before it is passed to the audio DACs. Bass enhancement can take
two different forms:
• Linear bass control: bass signals are amplified or attenuated by a user programmable
gain. This is independent of signal volume, and very high bass gains on loud signals
may lead to signal clipping.
• Adaptive bass boost: The bass volume is amplified by a variable gain. When the bass
volume is low, it is boosted more than when the bass volume is high. This method is
recommended because it prevents clipping, and usually sounds more pleasant to the
human ear.
Treble control applies a user programmable gain, without any adaptive boost function. Bass and
treble control are completely independent with separately programmable gains and filter
characteristics.
REGISTER
ADDRESS
R12 (0Ch)
Bass Control
BIT LABEL
7
BB
6
BC
3:0 BASS
[3:0]
R13 (0Dh)
6
TC
Treble Control
3:0 TRBL
[3:0]
Table 18 Graphic Equaliser
DEFAULT
0
0
1111
(Disabled)
0
1111
(Disabled)
DESCRIPTION
Bass Boost
0 = Linear bass control
1 = Adaptive bass boost
Bass Filter Characteristic
0 = Low Cutoff (130Hz at 48kHz sampling)
1 = High Cutoff (200Hz at 48kHz sampling)
Bass Intensity
Code
BB=0
BB=1
0000
+9dB
15 (max)
0001
+9dB
14
0010
+7.5dB
13
0011
+6dB
12
0100
+4.5dB
11
0101
+3dB
10
0110
+1.5dB
9
0111
0dB
8
1000
-1.5dB
7
1001
-3dB
6
1010
-4.5dB
5
1011
-6dB
4
1100
-6dB
3
1101
-6dB
2
1110
-6dB
1
1111
Bypass (OFF)
Treble Filter Characteristic
0 = High Cutoff (8kHz at 48kHz sampling)
1 = Low Cutoff (4kHz at 48kHz sampling)
Treble Intensity
0000 or 0001 = +9dB
0010 = +7.5dB
… (1.5dB steps)
1011 to 1110 = -6dB
1111 = Disable
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Pre-Production Rev 3.3 January 2007
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