Description of the audio processor part
TDA7461
3.1.1
3.1.2
Table 7. Input and source programming
Appl. N#
6
Pin number
8
9
Programming (1)
10
1
CDGND
PhoneGND
Phone
AMMONO
Startup 0/xxx11xxx
Startup 0/xxxx1xxx
FM
0/xxx11100
2
CDGND
PhoneGND AMRIGHT
AMLEFT
AM
0/xxx01011
Phone 0/xxx11010
Startup 0/xxxx1xxx
FM
0/xxx11100
3
CDGND
PhoneGND
Phone
AMSTD
AM
0/xxx01100
Phone 0/xxx11010
4
CDRGND
CDLGND
Phone
AMMONO
Startup 0/xxxx0xxx
Startup 0/xxxx0xxx
5
CDRGND
CDLGND AMRIGHT
AMLEFT
FM
0/xxx10100
AM
0/xxx00011
Startup 0/xxxx0xxx
FM
0/xxx10100
6
CDRGND
CDLGND
Phone
AMSTD
AM
0/xxx00100
Phone 0/xxx10010
1. Syntax 0/xxx11100 means: SUBADDRESS = 0 - DATA BYTE = xxx11100 (x - don’t care).
How to find the right input configuration
The best way to come to the desired configuration may be to go through the application tree
from the top to the bottom while making the specific decisions.
This way will lead to one of the six possible applications. Then take the number of the
application and go into the pinning table. Here you will find the special pinout as well as the
special programming codes for selecting sources.
For example in Appl. 6 the TDA7461 has to be configured while startup with the data byte
0/xxxx0xxx.
To select the FM, AM or phone source the last five significant bits of subaddress 0 have to
be changed, for any other source the last three bits are sufficient (see data byte
specification).
Input stages
Most of the input circuits are the same as in previous ST audio processors with exception of
the CD inputs (see Figure 4). In the meantime there are some CD players in the market
having a significant high source impedance which affects strongly the common mode
rejection of the normal differential input stage. The additional buffer of the CD input avoids
this drawback and offers the full common mode rejection even with those CD players.
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