AK4640_05 Datasheet, PDF (43/78 Pages) Asahi Kasei Microsystems – 16-Bit ΔΣ CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4640]
(2) I²C-bus Control Mode (I2C pin = “H”)
The AK4640 supports the standard-mode I²C-bus (max: 100kHz). The AK4640 does not support a fast-mode I²C-bus
system (max: 400kHz).
(2)-1. WRITE Operations
Figure 33 shows the data transfer sequence for the I²C-bus mode. All commands are preceded by a START condition. A
HIGH to LOW transition on the SDA line while SCL is HIGH indicates a START condition (Figure 39). After the
START condition, a slave address is sent. This address is 7 bits long followed by an eighth bit that is a data direction bit
(R/W). The most significant five bits of the slave address are fixed as “00100”. The next two bits are CAD1 and CAD0
(device address bits). These two bits identify the specific device on the bus. The hard-wired input pins (CAD1 and CAD0
pins) set these device address bits (Figure 34). If the slave address matches that of the AK4640, the AK4640 generates an
acknowledge and the operation is executed. The master must generate the acknowledge-related clock pulse and release
the SDA line (HIGH) during the acknowledge clock pulse (Figure 40). A R/W bit value of “1” indicates that the read
operation is to be executed. A “0” indicates that the write operation is to be executed.
The second byte consists of the control register address of the AK4640. The format is MSB first, and those most
significant 3-bits are fixed to zeros (Figure 35). The data after the second byte contains control data. The format is MSB
first, 8bits (Figure 36). The AK4640 generates an acknowledge after each byte has been received. A data transfer is
always terminated by a STOP condition generated by the master. A LOW to HIGH transition on the SDA line while SCL
is HIGH defines a STOP condition (Figure 39).
The AK4640 can perform more than one byte write operation per sequence. After receipt of the third byte the AK4640
generates an acknowledge and awaits the next data. The master can transmit more than one byte instead of terminating the
write cycle after the first data byte is transferred. After receiving each data packet the internal 5-bit address counter is
incremented by one, and the next data is automatically taken into the next address.
The data on the SDA line must remain stable during the HIGH period of the clock. The HIGH or LOW state of the data
line can only change when the clock signal on the SCL line is LOW (Figure 41) except for the START and STOP
conditions.
S
T
S
A
R/W="0"
T
R
O
T
P
SDA
Slave
S _Address
Sub
Address(n)
Data(n)
Data(n+1)
Data(n+x)
P
A
A
A
A
A
A
C
C
C
C
C
C
K
K
K
K
K
K
Figure 33. Data Transfer Sequence at the I²C-Bus Mode
0
0
1
0
0 CAD1 CAD0 R/W
(Those CAD1/0 should match with CAD1/0 pins)
Figure 34. The First Byte
0
0
0
A4
A3
A2
A1
A0
Figure 35. The Second Byte
D7
D6
D5
D4
D3
D2
D1
D0
Figure 36. Byte Structure after the second byte
MS0273-E-02
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2005/04