ISL22326 Datasheet, PDF (11/13 Pages) Intersil Corporation – Dual Digitally Controlled Potentiometers

ISL22326
An ACK, Acknowledge, is a software convention used to
indicate a successful data transfer. The transmitting device,
either master or slave, releases the SDA bus after
transmitting eight bits. During the ninth clock cycle, the
receiver pulls the SDA line LOW to acknowledge the
reception of the eight bits of data (See Figure 17).
The ISL22326 responds with an ACK after recognition of a
START condition followed by a valid Identification Byte, and
once again after successful receipt of an Address Byte. The
ISL22326 also responds with an ACK after receiving a Data
Byte of a write operation. The master must respond with an
ACK after receiving a Data Byte of a read operation.
A valid Identification Byte contains 1010 as the four MSBs,
and the following three bits matching the logic values
present at pins A2, A1, and A0. The LSB is the Read/Write
bit. Its value is “1” for a Read operation, and “0” for a Write
operation (See Table 3).
TABLE 3. IDENTIFICATION BYTE FORMAT
Logic values at pins A2, A1, and A0 respectively
1
0
1
0
A2 A1 A0 R/W
(MSB)
(LSB)
SCL
SDA
START
DATA
DATA
DATA
STABLE CHANGE STABLE
STOP
FIGURE 16. VALID DATA CHANGES, START AND STOP CONDITIONS
SCL FROM
MASTER
1
SDA OUTPUT FROM
TRANSMITTER
8
9
HIGH IMPEDANCE
SDA OUTPUT FROM
RECEIVER
HIGH IMPEDANCE
START
ACK
FIGURE 17. ACKNOWLEDGE RESPONSE FROM RECEIVER
SIGNALS FROM
THE MASTER
WRITE
S
T
A _{IDENTIFICATION}
R
BYTE
T
ADDRESS
BYTE
S
DATA
T
BYTE
O
P
SIGNAL AT SDA
1 0 1 0 A2 A1 A0 0 0 0 0 0
SIGNALS FROM
THE SLAVE
A
A
A
C
C
C
K
K
K
FIGURE 18. BYTE WRITE SEQUENCE
11
FN6176.0
July 17, 2006