STA381BWS datasheet(28/174 Pages) STMICROELECTRONICS

28 / 174 page

Device overview

STA381BWS

28/174

DocID018937 Rev 7

Device overview

The mentioned hyperlink in this section relates to the default New Map Section 6: Register

description: New Map.

4.1

Processing data path

The whole STA381BWS processing chain is composed of two consecutive sections. In the

first one dual-channel processing is implemented (Figure 6) and then each channel is fed

into the post-mixing block allowing to generate either a third channel (typically used in 2.1

output configurations together with crossover filters) or to have the channels processed by

the dual-band DRC block (2.0 output configuration with crossover filters used to define the

cutoff frequency of the two bands).

The first section begins with a 2x oversampling FIR filter allowing 2*Fs audio processing.

Then a selectable high-pass filter removes the DC level (enabled if HFB = 0). The channel 1

and 2 processing chain can include up to 8 filters, depending on the selected configuration

(bits BQL, BQ5, BQ6, BQ7 and XO[3:0]). By default, 4 independent filters per channel are

enabled, plus the pre-configured Bass and Treble controls (BQL=0, BQ5=0, BQ6=0,

BQ7=0).

The STA381BWS offers the possibility to share the filter coefficients between the two

processing channels. When this option is set (BQL=1), filters from the 1st to the 4th have

the same coeffcients set. Under these conditions, filters from the 5th to 7th can be used as

custom filters as well (provided the relevant BQx bits are set). Once again filter coefficients

are shared between the two processing channels.

Moreover the common 8th filter, from the subsequent processing section, can be available

on both channels (provided the pre-defined crossover frequencies are not used, XO[3:0]=0,

and the dual-band DRC is not used).

Figure 6. Processing path, first part

I2S Input

Interface

X2Over-

-sampling

FIR

Pre-

-scale

Hi-Pass

Filter

Biquad

Userd Defined Filters

De-emph

Biquad #5

Bass

Biquad #6

Treble

Biquad #7

Tone Control

X2Over-

-sampling

FIR

Pre-

-scale

Hi-Pass

Filter

Biquad

Userd Defined Filters

De-emph

Biquad #5

Bass

Biquad #6

Treble

Biquad #7

Tone Control

Sampling Frequency = Fs

Sampling Frequency = 2xFs

Obsolete

Product(s)

- Obsolete

Product(s)

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