sta381bw STMicroelectronics, sta381bw Datasheet - Page 150

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

Register description: Sound Terminal compatibility
7.22
7.22.1
7.22.2
150/168
Biquads from 1 to 7 have in the STA381BW the possibility to extend the coefficient range
from [-1,1) to [-4..4) which allows the implementation of high shelf filters that may require a
coefficient dynamic greater in absolute value than 1.
Three ranges are available, [-1;1) [-2;2) [-4;4). By default, the extended range is activated
Each biquad has its independent setting according to the following table.
Table 169. Coefficients extended range configuration
In this case the user can decide, for each filter stage, the right coefficients range. Note that
for a given biquad, the same range will be applied to left and right (channel 1 and
channel 2).
Crossover biquad does not have the availability of this feature, maintaining the [-1;1) range
unchanged.
Miscellaneous registers (address 0x4B, 0x4C)
Rate power-down enable (RPDNEN) bit (address 0x4B, bit D7)
In the STA381BW, by default, the power-down pin and I
commands to perform the fadeout. This default can be changed so that the fadeout can be
started using master volume. The RPDNEN bit, when set, activates this feature.
Bridge immediate off (BRIDGOFF) bit (address 0x4B, bit D5)
A fadeout procedure is started in the STA381BW once the PWDN function is enabled, and
after 13 million clock cycles (PLL internal frequency) the bridge is put in power-down
(tristate mode). There is also the possibility to change this behavior so that the power bridge
will be switched off immediately after the PWDN pin is tied to ground, without waiting for the
13 million clock cycles. The BRIDGOFF bit, when set, activates this function. Obviously the
immediate power-down will generate a pop noise at the output, therefore this procedure
must be used only in case pop noise is not relevant in the application. Note that this feature
RPDNEN
LPDP
D7
D7
0
0
CEXT_Bx[1]
0
0
1
1
LPD
D6
D6
1
1
BRIDGOFF
LPDE
D5
D5
1
0
Doc ID 018835 Rev 2
PNDLSL[2]
D4
D4
0
0
CEXT_Bx[0]
0
1
0
1
PNDLSL[1]
D3
D3
0
1
PNDLSL[0]
CPWMEN
2
D2
D2
C power-down act on mute
1
1
reserved
reserved
Reserved
D1
D1
0
0
Range
[-1;1)
[-2;2)
[-4;4)
STA381BW
SHEN
D0
D0
0
0