TDA7801PD datasheet(28/48 Pages) STMICROELECTRONICS

28 / 48 page

Functional description

TDA7801

28/48

DocID022674 Rev 4

6.9

Legacy mode

In case of applications without the I2C bus the TDA7801 could be turned on in legacy mode.

In order to put the device in legacy mode it is enough to tie the IC clock pin (PIN 27) at Vcc.

In this mode the device is turned on, as usual, with the ENABLE pin (PIN 2). The I2C Data

pin (PIN26) acts as analog mute. The device is set with all the instruction registers equal to zero.

In legacy mode the I2S interface does not support the TDM format.

6.10

Thermal protection

The TDA7801 has four thermal warnings (Tw1, Tw2, Tw3, Tw4) at different temperatures

which are stored on the I2C bus. Only one of the four thermal warnings could be sent to the

DIAG pin. The selection is done by an I2C bus.

A mute function dependent on temperature is present in order to protect the junction by

over-temperature with limited effects on the sound quality. For junction temperature over the

thermal warning threshold Tpl, the device is gradually carried in mute. The mute level

depends on the temperature: when the junction temperature reaches the Tpl threshold (refer

to Figure 32), the output signal is attenuated of 0.5 dB, while when the junction temperature

reaches Tph the output attenuation is 60 dB. This attenuation is performed without output

signal distortion.

Figure 32. Thermal muting diagram

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