ASAHI KASEI

[AK4385]

MS0246-E-01

2006/01

- 9 -

OPERATION OVERVIEW

System Clock

The external clocks, which are required to operate the AK4385, 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. 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 2~4).After exiting reset (PDN = “

↑”), the AK4385 is in Auto Setting Mode. In Auto Setting Mode

(ACKS = “1”: Default), as MCLK frequency is detected automatically (Table 5), and the internal master clock becomes

the appropriate frequency (Table 6), it is not necessary to set DFS0/1.

All external clocks (MCLK,BICK and LRCK) should always be present whenever the AK4385 is in the normal operation

mode (PDN= ”H”). If these clocks are not provided, the AK4385 may draw excess current and may fall into unpredictable

operation. This is because the device utilizes dynamic refreshed logic internally. The AK4385 should be reset by PDN=

“L” after threse clocks are provided. If the external clocks are not present, the AK4385 should be in the power-down

mode (PDN= “L”). After exiting reset at power-up etc., the AK4385 is in the power-down mode until MCLK and LRCK

are input.

DFS1

DFS0

Sampling Rate (fs)

0

0

Normal Speed Mode

8kHz~48kHz

Default

0

1

Double Speed Mode

60kHz~96kHz

1

0

Quad Speed Mode

120kHz~192kHz

Table 1. Sampling Speed (Manual Setting Mode)

LRCK

MCLK

BICK

fs

256fs

384fs

512fs

768fs

1152fs

64fs

32.0kHz

8.1920MHz

12.2880MHz

16.3840MHz

24.5760MHz

36.8640MHz

2.0480MHz

44.1kHz

11.2896MHz

16.9344MHz

22.5792MHz

33.8688MHz

N/A

2.8224MHz

48.0kHz

12.2880MHz

18.4320MHz

24.5760MHz

36.8640MHz

N/A

3.0720MHz

Table 2. System Clock Example (Normal Speed Mode @Manual Setting Mode)

LRCK

MCLK

BICK

fs

128fs

192fs

256fs

384fs

64fs

88.2kHz

11.2896MHz

16.9344MHz

22.5792MHz

33.8688MHz

5.6448MHz

96.0kHz

12.2880MHz

18.4320MHz

24.5760MHz

36.8640MHz

6.1440MHz

Table 3. System Clock Example (Double Speed Mode @Manual Setting Mode)

LRCK

MCLK

BICK

fs

128fs

192fs

64fs

176.4kHz

22.5792MHz

33.8688MHz

11.2896MHz

192.0kHz

24.5760MHz

36.8640MHz

12.2880MHz

Table 4. System Clock Example (Quad Speed Mode @Manual Setting Mode)