STV82X7 datasheet(38/156 Pages) STMICROELECTRONICS

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Dedicated Digital Signal Processor (DSP)

STV82x7

38/156

4.12

Automatic Loudness Control

As the human ear does not hear the audio frequency range the same way depending on the power

of the audio source, the Loudness Control corrects this effect by sensing the volume level and then

boosting bass and treble frequencies proportionally to middle frequencies at lower volume.

While maintaining the amplitude of the 1 kHz components at an approximately constant value, the

gain values of lower and higher frequencies are automatically progressively amplified up to +18 dB

when the audio volume level decreases.The maximum treble amplification can be adjusted from

0 dB (first order loudness) to +18 dB (second order loudness) in steps of 3 dB. As the volume is

proportional to the external audio amplification power, the loudness amplification threshold is

programmable in order to tune the absolute level. The Loudspeakers Loudness function is enabled

by setting the LS_LOUD_ON bit in register LS_LOUDNESS. The Loudspeakers Loudness

Threshold and Maximum Treble Gain values are also programmed in this register. The Headphone

Loudness function is enabled by setting the HP_LOUD_ON bit in register HP_LOUDNESS. The

Headphone Loudness Threshold and Maximum Treble Gain values are also programmed in this

The loudness cut-off frequency is 100 Hz.

4.13

Volume/Balance Control

The STV82x7 provides a Volume/Balance Control for all output channels configuration (except for

S/PDIF) with different volume level per channel (L, R, C, LS, RS, SubW, SCART). Its wide range

(from +11.875 to -116 dB, in a dB linear scale with a 0.125 dB step) largely covers typical home

applications (approx. 60 dB) while maintaining a good S/N ratio.

An extra Master Volume Control can apply an extra gain/attenuation on L, R, C, LS, RS and SubW

channels.

The Volume/Balance Control can operate in one of two different modes:

● In Differential mode (default value), the volume control is a common volume value for both the

Left and Right Loudspeakers or Headphone channels (see Figure 20) and complimentary

balance control is used (see Figure 21).

Figure 20: Volume Control

+11.875 dB

-116 dB

Mute

00h

3FFh

I²C Control

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