
ASAHI KASEI 
AKM CONFIDENTIAL
[AK4340] 
Rev.0.6 
2005/11 
- 10 - 
OPERATION OVERVIEW
 System Clock 
The AK4340 requires MCLK, BICK and LRCK external clocks. 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. 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) After exiting reset (PDN pin = “
↑
”), the AK4340 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.  
In parallel control mode, the sampling speed can be set by only ACKS pin. The internal DFS0 and DFS1 bits are fixed to 
“0”. Therefore, when ACKS pin is “L”, the AK4340 operates in Normal Speed Mode. The AK4340 operates in Auto 
Setting Mode at ACKS pin = “H”. In parallel control mode, the AK4340 does not support 128fs and 192fs of Double 
Speed Mode. 
All external clocks (MCLK, BICK and LRCK) should always be present whenever the AK4340 is in the normal operation 
mode (PDN pin = “H”). If these clocks are not provided, the AK4340 may draw excess current and may fall into 
unpredictable operation. This is because the device utilizes dynamic refreshed logic internally. The AK4340 should be 
reset by PDN pin = “L” after threse clocks are provided. If the external clocks are not present, the AK4340 should be in 
the power-down mode (PDN pin = “L”). After exiting reset at power-up etc., the AK4340 is in the power-down mode 
until MCLK and LRCK are input. 
DFS1 
DFS0 
0 
0 
Normal Speed Mode 
0 
1 
Double Speed Mode 
1 
0 
Quad Speed Mode 
Table 1. Sampling Speed (Manual Setting Mode) 
LRCK 
(kHz) 
DFS1 
DFS0 
Speed 
fs 
128fs 
192fs 
0 
0 
32.0 
- 
- 
0 
0 
44.1 
- 
- 
0 
0 
48.0 
- 
- 
0 
1 
88.2 
11.2896
16.9344
22.5792
0 
1 
96.0 
12.2880
18.4320
24.5760
1 
0 
176.4 
22.5792
33.8688
1 
0 
192.0 
24.5760
36.8640
Table 2. System Clock Example (Manual Setting Mode) 
Sampling Rate (fs) 
8kHz~48kHz 
60kHz~96kHz 
120kHz~192kHz 
Default 
MCLK(MHz) 
BICK 
(MHz)
64fs 
2.0480
2.8224
3.0720
5.6448
6.1440
11.2896
12.2880
Sampling 
256fs 
8.1920
11.2896
12.2880
384fs 
12.2880
16.9344
18.4320
33.8688
36.8640
- 
- 
512fs 
16.3840
22.5792
24.5760
- 
- 
- 
- 
768fs 
24.5760 
33.8688 
36.8640 
- 
- 
- 
- 
1152fs
36.8640
- 
- 
- 
- 
- 
- 
Normal 
Double 
- 
- 
Quad