sta381bw STMicroelectronics, sta381bw Datasheet - Page 25

• Manufacturer Part Number: sta381bw
• Description: Sound Terminal 2.1-channel High-efficiency Digital Audio System
• Manufacturer: STMicroelectronics

STA381BW
4
4.1
Device overview
The mentioned hyperlink in this section relates to the default New Map
description: New
Processing data path
The whole STA381BW processing chain is composed of two consecutive sections. In the
first one dual-channel processing is implemented
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 a 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 STA381BW 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 cross-over frequencies are not used, XO[3:0]=0,
and the dual-band DRC is not used).
Figure 4.
I2S Input
Interface
Sampling Frequency = 2xFs
Sampling Frequency = 2xFs
Processing path, first part
-sampling
-sampling
X2Over-
X2Over-
FIR
FIR
Sampling Frequency = Fs
Map.
-scale
-scale
Pre-
Pre-
Doc ID 018835 Rev 2
Hi-Pass
Hi-Pass
Filter
Filter
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#1
#1
Userd Defined Filters
Userd Defined Filters
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#2
#2
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#3
#3
(Figure
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#4
#4
4) and then each channel is fed
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De-emph
De-emph
Or
Or
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Biquad #6
Bass
Bass
Section 6: Register
Or
Or
Tone Control
Tone Control
Device overview
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Treble
Treble
Or
Or
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