TDA7410ND Datasheet, PDF (11/34 Pages) STMicroelectronics – Signal processor for car radio applications

TDA7410ND
Description of the audioprocessor part
5
Description of the audioprocessor part
5.1
Input matrix
The input matrix of the TDA7410ND offers several possibilities to adapt the audioprocessor
to the desired application (see Figure 1). Into the standard application we have:
● CD quasi differential
● Cassette stereo
● Phone
● AM mono
● Stereodecoder input
Figure 3. Input Stage
CD
100K
-
+
CDGND
100K
CASSETTE
PHONE
AM
MPX
100K
100K
100K
100K
STEREODECODER
IN GAIN
D05AU1613
5.2
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 volume stage during this time. In some cases, for example if the P 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 TDA7410D 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.
11/34