AK7755EN_16 Datasheet, PDF (88/109 Pages) Asahi Kasei Microsystems – DSP with Mono ADC Stereo CODEC + Mic/Lineout Amp

[AK7755]
The period of (1) varies by the setting value of DATT bit. The transition time of attenuation amount
from 0dB to -∞ and vice versa is shown below.
ATSPAD
0
1
LRCK Cycle
828/fs
828/fs x 4
(1)Period (max)
fs=48kHz
17.25ms
69ms
fs=44.1kHz
18.82ms
75.27ms
fs=8kHz
103.5ms
414ms
When changing channels, the input channel should be changed during (2). The period of (2) should be
around 200ms because there is some DC difference between the channels (3).
2-3. ADC Digital Volume
The ADC of the AK7755 has channel-independent digital volume control (256 levels, 0.5dB step).
VOLADL [7:0] bits (CONT15:D7-D0), VOLADR [7:0] bits (CONT16:D7-D0), VOLAD2L [7:0] bits
(CONT17:D7-D0) and VOLAD2R [7:0] bits (CONT1D:D7-D0) control these volume values
independently.
ADC Stereo Lch
VOLADL [7:0]
00h
01h
02h
:
2Fh
30h
31h
:
FDh
FEh
FFh
ADC Stereo Rch ADC2 Lch
ADC2 Rch
VOLADR [7:0] VOLAD2L [7:0] VOLAD2R [7:0]
00h
00h
00h
01h
01h
01h
02h
02h
02h
:
:
:
2Fh
2Fh
2Fh
30h
30h
30h
31h
31h
31h
:
:
:
FDh
FDh
FDh
FEh
FEh
FEh
FFh
FFh
FFh
Table 4. ADC Digital Volume Level Setting
Attenuation Level
+24.0dB
+23.5dB
+23.0dB
:
+0.5dB
0.0dB
-0.5dB
:
-102.5dB
-103.0dB
Mute (-∞)
(default)
Transition time between set values can be selected by ATSPAD bit (CONT0C: D5).
MODE
ATSPAD
ATT speed
0
0
1/fs
1
1
4/fs
Table 5. ADC Volume Transition Time Setting
The transition between set values is soft transition of 1021 levels in Mode 0. It takes 1021/fs
(21.3ms@fs=48kHz) from 00h to FFh(MUTE). If the PDN pin is set to “L”, the VOLADL/R[7:0] bits
are initialized to 30h.
014006643-E-00
- 88 -
2014/10