[AK4425A]
OPERATION OVERVIEW
■ System Clock
The external clocks required to operate the AK4425A are MCLK, LRCK and BICK. The master clock (MCLK) should be
synchronized with LRCK but the phase is not critical. The MCLK is used to operate the digital interpolation filter and the
delta-sigma modulator. The MCLK is used to operate the digital interpolation filter and the delta-sigma modulator. There
are two methods to set MCLK frequency. In Manual Setting Mode (ACKS = “0”: Register 00H), the sampling speed is set
by DFS0/1 (Table 1). The frequency of MCLK at each sampling speed is set automatically. (Table 2) When the power
applied, the AK4425A is in Auto Setting Mode. In Auto Setting Mode (ACKS = “1”: Default), as MCLK frequency is
detected automatically (Table 3), and the internal master clock becomes the appropriate frequency (Table 4), it is not
necessary to set DFS0/1.
The AK4425A is automatically placed in power saving mode when MCLK, LRCK and BICK stop during normal
operation mode, and the analog output is forced to 0V(typ). When MCLK, LRCK and BICK are input again, the
AK4425A is powered up. After power-up, the AK4425A is in the power-down mode until MCLK, LRCK and BICK are
input.
DFS1
DFS0
Sampling Rate (fs)
(default)
0
0
1
0
1
0
Normal Speed Mode
8kHz~48kHz
60kHz~96kHz
120kHz~192kHz
Double Speed Mode
Quad Speed Mode
Table 1. Sampling Speed (Manual Setting Mode)
LRCK
(kHz)
fs
BICK
(MHz)
64fs
Sampling
Speed
MCLK (MHz)
DFS1 DFS0
128fs
192fs
256fs
384fs
512fs
768fs
1152fs
0
0
0
0
0
1
1
0
0
0
1
1
0
0
32.0
44.1
48.0
88.2
96.0
-
-
-
-
-
-
8.1920
12.2880 16.3840 24.5760 36.8640
2.0480
2.8224
3.0720
5.6448
6.1440
11.2896
12.2880
Normal
11.2896 16.9344 22.5792 33.8688
12.2880 18.4320 24.5760 36.8640
-
-
-
-
-
-
11.2896 16.9344 22.5792 33.8688
12.2880 18.4320 24.5760 36.8640
22.5792 33.8688
24.5760 36.8640
-
-
-
-
-
-
-
-
Double
Quad
176.4
192.0
-
-
-
-
Table 2. System Clock Example
MCLK
1152fs
Sampling Speed
Normal (fs=32kHz only)
512fs
256fs
128fs
768fs
384fs
192fs
Normal
Double
Quad
Table 3. Sampling Speed(Auto Setting Mode: Default)
MS1127-E-01
2011/03
- 11 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
