8169 Datasheet, PDF (26/30 Pages) STMicroelectronics – DIGITAL AUDIO PROCESSOR WITH MULTICHANNEL DDX™

STA304A
12.11Phantom Center Register (add. 60h)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1
D0
Phantom
Setting bit 0 enables the phantom center channel feature. When this feature is on, the content of the center
channel is split and added to the L and R channels.
12.12DDX Gain Register (add. 62h)
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
bypass GCEN Vol₄ Vol₃ Vol₂ Vol₁ Vol₀ X
X
X
X
X
X
X
X
X
bypass: 0 means that the DDX gain depends from CRA bits 2 and 3
1 the DDX gain depends from D13-D9 bits plus D14 bit (CRA bit 2 and 3 are ignored)
GCEN: if D15 = 1 set (1) or remove (0) the ddx output compressor
Vol₄...Vol₀
Vol
dB
00000
+23.25
00001
00010
+22.5
+21.75
----
01111
+12
10000
+11.25
----
11101
+1.50
11110
+0.75
11111
0
The STA304A provides continuous digital gain and limiting functionality. Digital gain is variable from 0dB to
+23.25dB in 0.75dB steps based in the 62h register when the bit 15 is set. If the bit 15 is not set, th STA304A
defaults to the original Gain/Limiting truth table based on DDX_Gain bits (12.9). The GCEN bit when set enables
limiting to prevent clipping. This limiter uses a peak detect algoritthm for attack and a RMS detect for release.
The attack threshold is set at full DDX output power and will therefore reduce the gain when clipping is occuring.
The release threshold is set slightly below this to allow for a minimum dynamic range.
Figure 16.
GAIN/VOLUME
INPUT
GAIN
26/30
LIMITER
RMS
ATTENUATION
OUTPUT
SATURATION
D01AU1313