CS4525 datasheet(30/98 Pages) CIRRUS

30 / 98 page

DS726PP1

CS4525

6.1.4.1

Pre-Scaler

Applying any gain to a full-scale signal in the digital domain will cause the signal to clip. To prevent this,

a pre-scaler block is included prior to the internal digital signal processing blocks. This allows the input

signal to be attenuated before processing to ensure that any signal boosting, such as gain in a shelving

filter, will not cause a channel to clip.

The pre-scaler block allows up to -14.0 dB of attenuation in 2.0 dB increments and is controlled with the

PreScale[2:0] bits.

6.1.4.2

Digital Signal Processing High-Pass Filter

The CS4525 includes a high-pass filter at the beginning of the digital signal processing chain to remove

any DC content from the input signal prior to the remaining internal digital signal processing blocks. The

high-pass filter operates by continuously subtracting a measure of the DC offset from the input signal and

may be used regardless of the input data source.

The digital signal processing high-pass filter can be disabled by clearing the EnDigHPF bit.

6.1.4.3

Channel Mixer

The CS4525 implements independent channel mixers to provide for both mono mixes and channel swaps

for the left and right channels. The channel mixers are controlled by the LChMix[1:0] and RChMix[1:0] bits

in the Mixer Config register.

To allow stereo operation when a mono mix is configured, when the HP_DETECT/MUTE pin is configured

for headphone detection (the HP/Mute bit is set), the operation of the left channel mixer is affected by the

active state of the headphone detection input signal. In this configuration, when the left channel mixer is

configured for a mono mix (LChMix[1:0] = 01 or 10) and the headphone detection input signal becomes

active, the left channel mixer will be automatically reconfigured to output the left channel, thereby dis-

abling the mono mix. When the headphone detection input signal becomes inactive, the mixer will be au-

tomatically reconfigured to operate as dictated by the LChMix[1:0] bits.

It should be noted that the right channel mixer output is unaffected by the headphone detection input sig-

nal and will always operate as dictated by the RChMix[1:0] bits.

Referenced Control

PreScale[2:0]....................... “Pre-Scale Attenuation (PreScale[2:0])” on page 75

Referenced Control

EnDigHPF ........................... “Digital Signal Processing High-Pass Filter (EnDigHPF)” on page 77

Referenced Control

LChMix[1:0] ......................... “Left Channel Mixer (LChMix[1:0])” on page 76

RChMix[1:0] ........................ “Right Channel Mixer (RChMix[1:0])” on page 76

HP/Mute .............................. “HP_Detect/Mute Pin Mode (HP/Mute)” on page 70

CS4525 Datenblatt(PDF) 30 Page - Cirrus Logic