TDA7406T datasheet(18/49 Pages) STMICROELECTRONICS

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TDA7406T

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2.9 AC-coupling

In some applications additional signal manipulations are desired. For this purpose an AC-coupling is placed be-

fore the speaker-attenuators, which can be activated or internally shorted by I²C-Bus. In short condition the in-

put-signal of the speaker-attenuator is available at the AC-outputs. The input-impedance of this AC-inputs is

50k

Ω. In addition there are MixIn inputs available. With this inputs it is possible to mix an external signal to every

speaker with a mixing ratio of 50% (see Figure 15).

The source of front and rear speaker can be set independently. As source is possible to choose:

– internal dc coupling (not recommended)

– external ac coupling using ACIn pins

– external ac coupling using MixIn pins

– mixing of ACIn and MixIn pins (mixing ratio: 50%)

If the MixIn pins of the rear speaker are not used this inputs can be used as mixing inputs for the internal sub-

woofer filter.

Figure 15. AC/DC-coupling and MixIn Inputs

2.10 Speaker-Attenuator stage

Each of the four speakers and the subwoofer output has a separate volume control in the range: +15... -79dB

plus mute with a typical value of -90dB.

2.11 Output Mixer

A Mixing-stage is placed after each speaker gain/attenuator stage and can be set independently to mixing-

mode.

Having a full volume control for the Mix-signal in the range:+15... -79dB plus mute with a typical value of -90dB,

the stage offers a wide flexibility to adapt the mixing levels.

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