TDA7415CB datasheet(26/50 Pages) STMICROELECTRONICS

26 / 50 page

Description of the audio processor

TDA7415CB

26/50

5.3

Output path

As the Input-Section, the Output-Section of the TDA7415CB incorporates also three

independent stereo signal paths, where each can connect to two out of four AC-coupled,

single-ended inputs and to some dedicated signals originating from the input-section and/or

main-signal-path. For simplicity only one channel is shown in Figure 16. Interruption

switches follow the input selectors that can quickly toggle to the phone-, navigation-, or

phone/navigation-mix signal independently for each signal path and single L/R-channel. The

pre-selection of the interrupt source is common for all signal paths.

Figure 16.

Signal flow output section

Signal path 0 and 1 (front and rear) may optionally enter high-pass filters whereas signal

path 2 (other) can be low-pass filtered for subwoofer applications. Anti-radiation filters are

integrated for all signal paths but there are no anti-alias filters present at the inputs, since for

most signal sources it is unlikely to introduce significant high frequency energy. However, if

present, the system designer must take care to filter out high frequency components by

means of an external RC-low-pass filter located at the AC-input pins. Soft-mute stages and

a soft-step volume, that offer fast and click-less muting and/or volume changing follow all

three filters. The soft mute circuit will be described later.

Five stereo pairs of output buffers finally complete the Output-section: Signal-path 2

exclusively feeds a line driver output that is capable of 4VRMS output level as required by

external (remote) power amplifiers. The other signal-paths 1 & 2 feature both, a line driver

output and a dedicated internal (on board) power amplifier output with 3dB fixed gain. To

maximize the line-driver output swing, when the dual-supply option (VCC = 9V, VP = 12V) is

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