AK4137EQ Datasheet, PDF (42/65 Pages) Asahi Kasei Microsystems – 32bit SRC with PCM/DSD conversion

[AK4137]
■ Soft Mute Function
Manual Mode
The soft mute operation is performed in the digital domain of the SRC output. SRC soft mute is
controlled by the SMUTE pin in parallel control mode (PSN pin = “H”) or SMUTE bit in serial control
mode (PSN pin = “L”). The SRC output data is attenuated to  in 1024 OLRCK cycles (@ SMT1 pin
= “L” and SMT0 pin = “L”) by setting SMUTE pin to “H” (or SMUTE bit = “1”). When setting the
SMUTE pin to “L” (or SMUTE bit to “0”) the mute is cancelled and the output attenuation level
gradually changes to 0dB in 1024 OLRCK cycles (@ SMT1 pin = “L” and SMT0 pin = “L”). If the soft
mute is cancelled before attenuating to , the attenuation is discontinued and the attenuation level
returns to 0dB by the same cycles. The soft mute is effective for changing the signal source without
stopping the signal transmission. Soft mute cycle is set by SMT1-0 pins. The setting of SMT1-0 pins
(or SMT2-0 bits) must not be changed during soft mute transition.
SMT1pin
L
L
H
H
SMT0 pin
L
H
L
H
Period
1024/fso
2048/fso
4096/fso
8192/fso
fso=48kHz
21.3ms
42.7ms
85.3ms
170.7ms
fso=96kHz
10.7ms
21.3ms
42.7ms
85.3ms
fso=192kHz
5.3ms
10.7ms
21.3ms
42.7ms
fso=384kHz
2.7ms
5.3ms
10.7ms
21.3ms
fso=768kHz
1.3ms
2.7ms
5.3ms
10.7ms
SMT2
bit
0
0
0
0
1
1
1
1
SMT1
bit
0
0
1
1
0
0
1
1
SMT0
bit
0
1
0
1
0
1
0
1
Period fso=48kHz fso=96kHz fso=192kHz fso=384kHz fso=768kHz
1024/fso 21.3ms 10.7ms
5.3ms
2048/fso 42.7ms 21.3ms
10.7ms
4096/fso 85.3ms 42.7ms
21.3ms
8192/fso 170.7ms 85.3ms
42.7ms
16384/fso 341.3ms 170.7ms 85.3ms
32768/fso 682.7ms 341.1ms 170.7ms
(1024/fso)
-
-
-
(1024/fso)
-
-
-
Table 6. Soft Mute Cycle Setting
2.7ms
5.3ms
10.7ms
21.3ms
42.7ms
85.3ms
-
-
1.3ms
2.7ms
5.3ms
10.7ms
21.3ms
42.7ms
-
-
SMUTE
0dB
(1)
Attenuation Level
-
(1)
(3)
SDTO
Figure 36. Soft Mute Manual Mode
Rev. 0.2
- 42 -
2014/06