MSP 34x0G
DATA SHEET
All MSP 34x0G are shipped without Micronas VOICE
except otherwise ordered. When a Micronas VOICE -
version of the MSP 34x0G is ordered, it carries a spe-
cial marking on the chip for identification. The Micro-
nas VOICE functionality must be enabled by writing a
"license key" into the MSP 34x0G. For information on
how to obtain this license key from Micronas, please
contact your Micronas sales representative.
2.5.5. Loudspeaker and Headphone Outputs
The following baseband features are implemented in
the loudspeaker and headphone output channels:
bass/treble, loudness, balance, and volume. A square
wave beeper can be added to the loudspeaker and
headphone channel. The loudspeaker channel addi-
tionally performs: equalizer (not simultaneously with
bass/treble), spatial effects, and a subwoofer cross-
over filter.
2.5.4. Automatic Volume Correction (AVC)
Different sound sources (e.g. terrestrial channels, SAT
channels, or SCART) fairly often do not have the same
volume level. Advertisements during movies usually
have a higher volume level than the movie itself. This
results in annoying volume changes. The Automatic
Volume Correction (AVC) solves this problem by
equalizing the volume level.
2.5.6. Subwoofer Output
The subwoofer signal is created by combining the left
and right channels directly behind the loudness block
using the formula (L+R)/2. Due to the division by 2, the
D/A converter will not be overloaded, even with full
scale input signals. The subwoofer signal is filtered by
a third-order low-pass with programmable corner fre-
quency followed by a level adjustment. At the loud-
speaker channels, a complementary high-pass filter
can be switched on. Subwoofer and loudspeaker out-
put use the same volume (Loudspeaker Volume Reg-
ister).
To prevent clipping, the AVC’s gain decreases quickly
in dynamic boost conditions. To suppress oscillation
effects, the gain increases rather slowly for low level
inputs. The decay time is programmable by means of
the AVC register (see page 33).
For input signals ranging from −24 dBr to 0 dBr, the
AVC maintains a fixed output level of −18 dBr. Fig. 2–4
shows the AVC output level versus its input level. For
prescale and volume registers set to 0 dB, a level of
0 dBr corresponds to full scale input/output. This is
dB
5
Amplitude @dBD
0
1
0
– SCART input/output 0 dBr = 2.0 Vrms
3
−5
−10
−15
−20
−25
– Loudspeaker and Aux output 0 dBr = 1.4 Vrms
2
output level
[dBr]
−18
−24
200
f
2000 Hz
input level
[dBr]
−30
−24
−18
−12
−6
0
Fig. 2–5: Frequency response of subwoofer filter
0: sharp edge
Fig. 2–4: Simplified AVC characteristics
1: medium edge
2: soft edge
3: very soft edge
14
May 27, 2003; 6251-476-1DS
Micronas
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