WM8758B Datasheet, PDF (46/90 Pages) Wolfson Microelectronics plc – Stereo CODEC with Headphone Driver and Line Out

WM8758B
Production Data
VOLUME BOOST
The limiter has programmable upper gain which boosts signals below the threshold to compress the
dynamic range of the signal and increase its perceived loudness. This operates as an ALC function
with limited boost capability. The volume boost is from 0dB to +12dB in 1dB steps, controlled by the
LIMBOOST register bits.
The output limiter volume boost can also be used as a stand alone digital gain boost when the limiter
is disabled.
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REGISTER
ADDRESS
R24
DAC digital
limiter control
1
R25
DAC digital
limiter control
2
BIT
LABEL
3:0 LIMATK
7:4 LIMDCY
8
LIMEN
3:0 LIMBOOST
DEFAULT
0010
0011
0
0000
DESCRIPTION
Limiter Attack time (per 6dB gain
change) for 44.1kHz sampling. Note
that these are proportionally related to
sample rate.
0000 = 94us
0001 = 188s
0010 = 375us
0011 = 750us
0100 = 1.5ms
0101 = 3ms
0110 = 6ms
0111 = 12ms
1000 = 24ms
1001 = 48ms
1010 = 96ms
1011 to 1111 = 192ms
Limiter Decay time (per 6dB gain
change) for 44.1kHz sampling. Note
that these are proportionally related to
sample rate:
0000 = 750us
0001 = 1.5ms
0010 = 3ms
0011 = 6ms
0100 = 12ms
0101 = 24ms
0110 = 48ms
0111 = 96ms
1000 = 192ms
1001 = 384ms
1010 = 768ms
1011 to 1111 = 1.536s
Enable the DAC digital limiter:
0=disabled
1=enabled
Limiter volume boost (can be used as a
stand alone volume boost when
LIMEN=0):
0000 = 0dB
0001 = +1dB
0010 = +2dB
… (1dB steps)
1011 = +11dB
1100 = +12dB
1101 to 1111 = reserved
PD, Rev 4.4, January 2012
46