Rainbow Electronics MAX98089 - Manual (Page 93)

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MAX98089
Low-Power, Stereo Audio Codec
with FlexSound Technology
Parametric Equalizer
The parametric EQ contains five independent biquad
filters with programmable gain, center frequency, and
bandwidth. Each biquad filter has a gain range of Q12dB
and a center frequency range from 20Hz to 20kHz. Use a
filter Q less than that shown in Figure 22 to achieve ideal
frequency responses. Setting a higher Q results in non-
ideal frequency response. The biquad filters are series
connected, allowing a total gain of Q60dB.
Table 16. Automatic Level Control Registers
Figure 22. Maximum Recommended Filter Q vs. Frequency
CENTER FREQUENCY (Hz)
MAXIMUM RECOMMENDED FILTER Q
10,000 1000
1
10
100
1000
0.1
100 100,000
f s = 8kHz
f s = 48kHz
f s = 96kHz
REGISTER BIT NAME DESCRIPTION
0x43
7 ALCEN
ALC Enable
Enables ALC on both the DAI1 and DAI2 playback paths.
0 = Disabled
1 = Enabled
6
ALCRLS
ALC and Excursion Limiter Release Time
Sets the release time for both the ALC and Excursion Limiter. See the Excursion Limiter
section for Excursion Limiter release times. ALC release time is defined as the time
required to adjust the gain from 12dB to 0dB.
VALUE ALC RELEASE TIME (s)
5
000 8
001 4
010 2
011 1
4
100 0.5
101 0.25
110 Reserved
111 Reserved
3 ALCMB
Multiband Enable
Enables dual-band processing with a 5kHz center frequency. SR1 and SR2 must be
configured properly to achieve the correct center frequency for each playback path.
0 = Single-band ALC
1 = Dual-band ALC
2
ALCTH
Low Signal Threshold
Selects the minimum signal level to be boosted by the ALC.
000 = -JdB (low-signal threshold disabled)
001 = -12dB
010 = -18dB
011 = -24dB
100 = -30dB
101 = -36dB
110 = -42dB
111 = -48dB
1
0