TDA7415CB datasheet(28/50 Pages) STMICROELECTRONICS

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Description of the audio processor

TDA7415CB

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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

In a dual-supply application (VCC = 8.5V, VP = 12V) the output gain should be set to 9dB to

obtain a 4VRMS output level. For a single-supply application (VCC =VP = 8.5V) there is still

an output level of 2.75VRMS 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.

5.3.4

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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