TDA7403DTR STMicroelectronics, TDA7403DTR Datasheet - Page 6

• Manufacturer Part Number: TDA7403DTR
• Description: IC PROCESSOR BASIC SIGNAL SO-20
• Manufacturer: STMicroelectronics
• Type: Car Signal Processorr

Specifications of TDA7403DTR

• Applications: Automotive Systems
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TDA7403
DESCRIPTION OF THE AUDIOPROCESSOR
Figure 1. Input stages
Input stages
The input circuits are the same as in preceeding
ST audioprocessors with exception of the CD in-
puts (see figure 1).
The typical input impedance is 100k .
AutoZero
In order to reduce the number of pins there is no
AC coupling between the In-Gain and the follow-
ing stage, so that any offset generated by or be-
fore the In-Gain stage would be transferred or
even amplified to the output.
To avoid that effect a special offset cancellation
stage called AutoZero is implemented.
To avoid audible clicks the audioprocessor is
muted before the loudness stage during this time.
In some cases, for example if the P is executing
a refresh cycle of the I
not useful to start a new AutoZero action because
no new source is selected and an undesired mute
would appear at the outputs. For such applica-
tions the TDA7403 could be switched in the "Auto
Zero Remain" mode (Bit 6 of the subaddress
byte). If this bit is set to high, the DATABYTE 0
could be loaded without invoking the AutoZero
and the old adjustment value remains.
Softmute
The digitally controlled softmute stage allows
muting/demuting the signal with a I
grammable slope. The mute process can either
be activated by the softmute pin or by the I
bus. The slope is realized in a special S shaped
curve to mute slow in the critical regions (see fig-
ure 2).
For timing purposes the Bit 3 of the I
put register is set to 1 from the start of muting un-
til the end of demuting.
6/25
CASSETTE
MPX
AM
2
C bus programming, it is
100K
100K
100K
2
2
C bus pro-
C bus out-
STEREODECODER
2
C
Figure 2. 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.
Figure 3. Soft Step Timing
Note: For steps more than 1dB the softstep mode should be
deactivated because it could generate a 1dB error during the
blend-time
-1dB
-2dB
+SIGNAL
2dB
1dB
-SIGNAL
I
VOUT
2
MUTE
C BUS
EXT.
OUT
REF
1
1
D98AU951
10ms
D97AU634
IN GAIN
D97AU635
Time
Time