TDA7417

Description of the audioprocessor

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4

Description of the audioprocessor

4.1

Input stages

In the basic configuration, one stereo quasi-differential, one selectable full-differential and

two single ended stereo inputs are available. As Figure 3 shown.

Quasi-differential stereo Input (QD)

The QD input is implemented as a buffered quasi-differential stereo stage with 100k

Ω input-

impedance at each input. The attenuation is fixed to -3.5dB in order to adapt the incoming

signal level.

Single-ended stereo input (SE1, SE2)

The input-impedance at each input is 100k

Ω and the attenuation is fixed to -3.5dB for

incoming signals.

Full differential stereo Input (FD)

The FD input is implemented as a selectable full-differential stereo stage with 50k input-

impedance at each input or high impedance status. The attenuation is fixed to -3.5dB in

order to adapt the incoming signal level.The high impedance status is 100k

Ω

Figure 3.

Input stage

4.2

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. generated 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. 0.32ms

for the alignment. To avoid audible clicks the Audio processor is muted before the loudness

stage during this time.

Quasi-differential

SEL1/SER1

SEL2/SER2

Full-differential

Mute

InGain