ASAHI KASEI

[AK4340]

MS0501-E-00

2006/04

- 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

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

(kHz)

MCLK(MHz)

BICK

(MHz)

DFS1

DFS0

Sampling

Speed

fs

128fs

192fs

256fs

384fs

512fs

768fs

1152fs

64fs

0

0

32.0

-

-

8.1920

12.2880

16.3840

24.5760

36.8640

2.0480

0

0

44.1

-

-

11.2896

16.9344

22.5792

33.8688

-

2.8224

0

0

Normal

48.0

-

-

12.2880

18.4320

24.5760

36.8640

-

3.0720

0

1

88.2

11.2896

16.9344

22.5792

33.8688

-

-

-

5.6448

0

1

Double

96.0

12.2880

18.4320

24.5760

36.8640

-

-

-

6.1440

1

0

176.4

22.5792

33.8688

-

-

-

-

-

11.2896

1

0

Quad

192.0

24.5760

36.8640

-

-

-

-

-

12.2880

Table 2. System Clock Example (Manual Setting Mode)