BD9406KS2 Datasheet, PDF (17/38 Pages) Rohm – 28bit Audio DSP with Built-in 2ch ADC, 6ch DAC and ASRC

BU9406KS2
Technical Note
4. Digital Sound Processing (DSP)
BU9406KS2’s digital sound processing (DSP) section is constructed with specific hardware optimal for FPD TVs.
BU9406KS2 uses this special DSP to perform the following processes:
Pre-scaler, Channel Mixer, Pseudo-Stereo, Surround, P²Bass, P²Treble, Parametric Equalizer,
EVR & Balance, Compression, Post-scaler, Clipper
4-1. Overview and Signal Flow of DSP Section
Word length:
28 bit (DATA RAM)
Machine Cycle:
Multiplier:
Adder:
40.7ns (512fs, fs=48kHz)
28×24 → 52 bit
28＋28 → 28 bit
Data RAM:
256×28 bit
Coefficient RAM:
128×24 bit
Sampling Frequency:fs=48kHz
Master Clock:
512fs (24.576MHz, fs=48kHz)
16bit and 24bit digital signals are input to the DSP, but there is an
overflow margin of +4bit (+24dB) on the top side.
For processes that exceed this range, there is a clipping process within the DSP.
Data
RAM
Input
0
MUX
MUX
M
U
X
ADD
Acc
Output
Coefficient
RAM
Decoder
Circuit
Input
Pre-
Scaler
Channel
Mixer
Pseudo
Stereo
Surround
P2Bass
P2Treble
Parametric
EQ
EVR
＆
Balance
Compressi
on
Post-
Scaler
Clipper
Output
Digital Audio Processing Signal Flow
4-2. Pre-Scaler
When the digital signals are input to the sound DSP the level may be full-scale input, causing overflow from surround or
equalizer treatment, so the pre-scaler adjusts the input gain.
Analog signals are changed to digital values with the A/D converter, and the gain can be adjusted with the pre-scaler even
when the input level is low.
The adjustment range can be configured in 2dB increments from +16dB to -44dB.
Default = 00
Select Address
&h20 [ 4：0 ]
Command Value
00
01
02
03
04
05
06
07
Gain
0dB
-2dB
-4dB
-6dB
-8dB
-10dB
-12dB
-14dB
Operation Description
Command Value
08
09
0A
0B
0C
0D
0E
0F
Gain
-16dB
-18dB
-20dB
-22dB
-24dB
-26dB
-28dB
-30dB
Command Value
10
11
12
13
14
15
16
17
Gain
-32dB
-34dB
-36dB
-38dB
-40dB
-42dB
-44dB
-∞
Command Value
18
19
1A
1B
1C
1D
1E
1F
Gain
+16dB
+14dB
+12dB
+10dB
+8dB
+6dB
+4dB
+2dB
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2012.03 - Rev.A