BD9406KS2 Datasheet, PDF (30/38 Pages) Rohm – 28bit Audio DSP with Built-in 2ch ADC, 6ch DAC and ASRC

BU9406KS2
Technical Note
6. 8x Over-Sampling Digital Filter (DF)
In each BU9406KS2 audio analog signal output DAC, an 8x over-sampling digital filter is inserted into the previous step of
the DAC input.
In addition to filter calculations, this block also performs pre-scaler, volume and Lch/Rch mix functions.
BU9406KS2’s DF+DAC configurations are as follows:
DF1
Pre-Scaler
Volume
Channel Mixer
8x Over-sampling
Filter
DF2
Pre-Scaler
Volume
Channel Mixer
8x Over-sampling
Filter
DF3
Pre-Scaler
Volume
Channel Mixer
8x Over-sampling
Filter
ΔΣDAC
AOUTL3
(37PIN)
AOUTR3
(33PIN)
ΔΣDAC
AOUTL2
(30PIN)
AOUTR2
(26PIN)
16bitDAC
AOUTL1
(23PIN)
AOUTR1
(22PIN)
6-1. Pre-Scaler Function
The signal levels are adjusted in order to bring out the audio DAC performance.
For DF1, refer to &h80[7:0] and &h81[7:0]. The default value is h4000.
For DF2, refer to &h83[7:0] and &h84[7:0]. The default value is h4000.
For DF3, refer to &h86[7:0] and &h87[7:0]. The default value is h4000.
6-2. Volume Function
The volume value can be configured in 0.5dB increments from +6dB to -121dB.
To change the volume value, coefficient soft transition takes place. The transition time from 0dB to mute is approximately
21ms.
Default = 0Ch
Select Address
DF1 &h82 [ 7：0 ]
DF2 &h85 [ 7：0 ]
DF3 &h88 [ 7：0 ]
Operation Description
Calculation format: (12-command value)x0.5dB
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2012.03 - Rev.A