TDA7803A datasheet(35/72 Pages) STMICROELECTRONICS

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DS12195 Rev 7

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TDA7803A

Functional description

6.9.1

Auto-mute threshold

The device in play mode is put in mute when the supply voltage gets below the VlowM

threshold.

The muting strategy for this kind of event is reported in Figure 38. Both analog and digital

mute start when the supply voltage is below VlowM_HIGH. The digital mute transition lasts a

period TMUTE. The analog mute attenuation is proportional to Vs; when Vs is at VlowM_LOW

the mute attenuation is AM.

Note that, once it is engaged, the digital mute procedure will apply the AM attenuation. It is

not possible to stop it and move the device to play mode in advance. The concept of this

procedure is to avoid that fast oscillation on Vs can generate fast oscillation on the output.

Figure 38. Low voltage mute attenuation, supply voltage variation (Vs); result digital

attenuation (At)

When the battery goes below the auto-mute low threshold, it is possible to disable the digital

muting if IB2 D2 = "1". In this case the mute will be only analog.

The digital mute is also disabled during the turn-on diagnostic.

6.9.2

Mute and unmute commutation time

6.10

Class SBI - Improved high efficiency principle

TDA7803A embeds an improved high efficiency feature that minimizes the power dissipated

through the heat sink basing on the musical signal characteristic. All channels are

connected to a common bar by means of four power switches. When an input signal goes

TMUTE

t(sec)

Vs/Attenuation(At)

TMUTE

At=1

VAM-HIGH

VAM-LOW

GAPGPS00812

Table 10. Mute and unmute commutation time

Parameter

Test condition

Typ.

Unit

Mute and unmute commutation time

Programmable by I2C bus register

IB2(7:5) Fs = 44.1 kHz

1.45

180

370

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