PRELIMINARY DATA SHEET
UAC 3552A
2.2.2.5. Bass Boost Control
2.2.2.7. Volume and Balance Control
The bass boost algorithm provides an additional 12-dB
gain for the low-frequency components. The character-
istic is shown in Fig. 2–6.
The volume and balance control operate separately on
the left and right channel.
Table 2–7: Volume and Balance Control
dB
Min
Max
Step
14
12
−75 dB
0 dB
0.5 dB
10
8
The volume control is realized in the analog back-end.
This preserves high audio quality (SNR) at low volume
settings because signal and noise are attenuated in
the same way, which is not the case for pure digital vol-
ume control. The UAC 3552A uses digital volume con-
trol only for the fine tuning of the 0.5 dB step size. The
volume setting is smoothed by an internal ramping
algorithm in order to avoid audible clicks during volume
change.
6
4
2
0
10.
20.
50.
100.
200.
500.
1000.
Hz
Fig. 2–6: Bass boost
The splitting between analog and digital volume is han-
dled by the UAC 3552A automatically.
The bass boost works on both channels and can be
switched on and off under USB control.
2.2.3. Mute Control
The mute control is part of the volume system in the
UAC 3552A. It functions simultaneously on both chan-
nels and can be switched on and off under USB con-
trol. As with the volume control, clicks are avoided by a
ramping algorithm.
2.2.2.6. Parametric Equalizer
The parametric equalizer is a non-USB audio feature.
It allows the compensation of unwanted frequency
responses of a speaker. Alternatively, frequency
responses can be set to suit individual tastes. The
equalizer consists of 5 individually adjustable bands.
The control parameters and the parameter range for
each band is shown in Table 2–6.
2.2.3.1. Oversampling
The oversampling filter increases the audio sampling
rate by a factor of 4. The final upsampling to the noise-
shaping rate is handled by a sample and hold circuit.
The pass-band characteristic of the oversampling filter
is shown in Fig. 2–7.
Table 2–6: Equalizer Parameters
Parameter
Min
Max
15 kHz
+6 dB
3
center frequency
gain/attenuation
filter quality (Q)
50 Hz
−6 dB
0.5
dB
0
-0.1
-0.2
-0.3
-0.4
-0.5
The adjustment of the equalizer is supported by an
application program that allows to set up frequency
responses and to download the corresponding filter
coefficients into the UAC 3552A. When the frequency
response fits the target, it can be programmed into the
on-chip EEPROM. The UAC 3552A is shipped with a
flat frequency response.
0
5000
10000
15000
20000
kHz
Fig. 2–7: 1 to 4 Oversampling filter, pass-band
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