TDA7419 Datasheet, PDF (9/30 Pages) STMicroelectronics – 3 BAND CAR AUDIO PROCESSOR

TDA7419
5.2 AutoZero
The AutoZero allows a reduction of the number of pins as well as external components by canceling any
offset generated by or before the In-Gain-stage (Please notice that externally generated offsets, e.g. gen-
erated through the leakage current of the coupling capacitors, are not canceled).
The auto-zeroing is started every time the input source is changed and needs max. 0.3ms for the align-
ment. To avoid audible clicks the Audio processor is muted before the loudness stage during this time.
The AutoZero feature is only present in the main signal-path.
5.2.1 AutoZero-Remain
In some cases, for example if the P is executing a refresh cycle of the IIC-Bus-programming, it is not use-
ful to start a new AutoZero-action because no new source is selected and an undesired mute would ap-
pear at the outputs. For such applications, it can be switched in the AutoZero-Remain-Mode (Bit 6 of the
subaddress-byte). If this bit is set to high, the AutoZero will not be invoked and the old adjustment-value
remains.
5.3 Loudness
There are four parameters programmable in the loudness stage:
5.3.1 Attenuation
Figure 5 shows the attenuation as a function of frequency at f_P = 400Hz
Figure 5. Loudness Attenuation @ f_P = 400Hz.
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