E-TDA7461ND View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'E-TDA7461ND' PDF : 48 Pages View PDF
TDA7461
Description of the audio processor part
The TDA7461 can be configured with an additional input; if the AC coupling before the
speaker stage is not used (bit 7 in subaddress 5 set to "1") ACINL and ACINR pins can be
used as an additional stereo input.
Figure 4. Input stages
CD
100K
CDGND
PHONE
PH_GND
CASSETTE
100K
15K
15K
15K
15K
15K
-
+
15K
15K
-
+
15K
IN GAIN
AM
MPX
100K
100K
STEREODECODER
D97AU633A
3.1.3
AutoZero
In order to reduce the number of pins there is no AC coupling between the In-Gain and the
following stage, so that any offset generated by or before 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 μP is executing a refresh cycle of the I2C bus
programming, it is 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 applications the
TDA7461 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.
3.2
Mux output
The MUX_L and MUX_R outputs can provide selectively the output of the input multiplexer
(Speaker RF register, Byte 8, bit 6=1) or the output of the stereo decoder (Speaker RF
register Byte 8 bit 6=0).
If bit D3 byte 10 (Stdec Register) is set to 1, then the stdec signal is automatically muted,
when another source is selected at the input multiplexer.
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