TDA7415CB Datasheet, PDF (28/50 Pages) STMicroelectronics – Car radio multimedia signal processor

Description of the audio processor
TDA7415CB
Remark: Both filters offer a 'Butterworth' roll-off response
5.3.3
Line driver output stage (presenting the reference concept)
In order to adapt to two different supply-voltages for the dual-supply option, while
maintaining the highest possible output swing when only a single supply is available, the
line-driver output was realized as differential amplifier biased around the two device
references PREF and Vref3V3 (see Figure 19). The output DC-voltage precisely tracks the
DC-voltage present at the PREF-pin that is half the VP-supply. However, forcing the PREF
pin to any desired value could alter this DC-voltage, neglected the remaining output swing.
Figure 19. Line-driver output with reference generation scheme
5.3.4
In a dual-supply application (V_CC = 8.5V, V_P = 12V) the output gain should be set to 9dB to
obtain a 4VRMS output level. For a single-supply application (V_CC =V_P = 8.5V) there is still
an output level of 2.75V_RMS obtainable. Consequently, to avoid clipping in the output stages
the gain needs to be reduced to 5.5dB. For the programming of the output gain, see the
programming chapter.
Proper power sequencing is no critical issue for the TDA7415. However, it is recommended
that both supply-voltages should follow each other within one diode forward-drop (<1V)
before reaching their final value.
Soft mute
As can be seen from the block-diagram in figure 1, there are 6 soft-mute circuits placed
inside the TDA7415CB: Three each, in both the Input-section and the Output-section that
serve the independent signal-paths. A soft-mute can either be achieved by pulling one of the
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