CS4525 datasheet(34/98 Pages) CIRRUS

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DS726PP1

CS4525

6.1.4.7

Adaptive Loudness Compensation

The CS4525 includes adaptive loudness compensation to enhance the audibility of program material at

low volume levels. The adaptive loudness compensation feature operates by varying the bass and treble

boost of the tone control shelving filters as the volume level changes.

The level of boost added to the shelving filters is determined by the average of the effective volume set-

tings of channels A and B after the master volume control. As this average volume setting decreases from

0 dB, the boost of the bass and treble shelving filters is gradually increased until it reaches the maximum

boost level of 12.0 dB. As the volume is increased, the boost applied due to the adaptive loudness com-

pensation feature will be gradually removed until it reaches the level specified by the Treble[3:0] and

Bass[3:0] bits in the Tone Control register.

The adaptive loudness compensation feature is enabled by setting the Loudness bit in the Tone Config

applies bass and treble boost accordingly. When disabled, any treble or bass boost applied due to the

loudness feature will be removed.

Because the adaptive loudness compensation filter operates by adjusting the boost level of the tone con-

trol shelving filters, it is necessary that they be enabled with the EnToneCtrl bit in the Tone Config register

in order for the loudness feature to be operational. If the tone control filters are disabled, the adaptive loud-

ness compensation feature will not be functional.

Referenced Control

Loudness............................. “Adaptive Loudness Compensation Control (Loudness)” on page 76

EnToneCtrl .......................... “Tone Control Enable (EnToneCtrl)” on page 77

TrebFc[1:0].......................... “Treble Corner Frequency (TrebFc[1:0])” on page 77

BassFc[1:0] ......................... “Bass Corner Frequency (BassFc[1:0])” on page 77

Treble[3:0] ........................... “Treble Gain Level (Treb[3:0])” on page 78

Bass[3:0] ............................. “Bass Gain Level (Bass[3:0])” on page 78

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