TDA7400 ST Microelectronics, TDA7400 Datasheet - Page 13

• Manufacturer Part Number: TDA7400
• Description: ADVANCED CAR SIGNAL PROCESSOR
• Manufacturer: ST Microelectronics

Figure 5. Softmute Timing
Note: Please notice that a started Mute action is always terminated
and could not be interrupted by a change of the mute signal.
til the end of demuting.
Bass
There are four parameters programmable in the
bass stage: (see figs 6, 7, 8, 9):
Attenuation
Figure 6 shows the attenuation as a function of
frequency at a center frequency at a center fre-
quency of 80Hz.
Central Frequency
Figure 7 shows the four possible center frequen-
cies 60,70,80 and 100Hz.
Figure 6. Bass Control @ fc = 80Hz, Q = 1
-10.0
-15.0
15.0
10.0
-5.0
5.0
0.0
10.0
+SIGNAL
-SIGNAL
I
2
MUTE
EXT.
C BUS
OUT
REF
1
1
100.0
D97AU634
1.0K
Time
10.0K
Quality Factors
Figure 8 shows the four possible quality factors 1,
1.25, 1.5 and 2.
DC Mode
In this mode the DC gain is increased by 5.1dB.
In addition the programmed center frequency and
quality factor is decreased by 25% which can be
used to reach alternative center frequencies or
quality factors.
TREBLE
There are two parameters programmable in the
treble stage (see figs 10, 11):
Attenuation
Figure 10 shows the attenuation as a function of
frequency at a center frequency of 17.5KHz.
Center Frequency
Figure 11 shows the four possible Center Fre-
quency (10, 12.5, 15 and 17.5kHz).
Speaker Attenuator
The speaker attenuators have exactely the same
structure and range like the Volume stage.
FUNCTIONAL DESCRIPTION OF STEREODE-
CODER
The stereodecoder part of the TDA7400D (see
Fig. 12) contains all functions necessary to de-
modulate the MPX signal like pilot tone depend-
ent MONO/STEREO switching as well as
”stereoblend” and ”highcut” functions.
Figure 7. Bass Center @ Gain = 14dB, Q = 1
15.0
12.5
10.0
7.5
5.0
2.5
0.0
10.0
100.0
1.0K
TDA7400
10.0K
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