ISL12058IUZ View Datasheet(PDF) - Intersil
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ISL12058IUZ Datasheet PDF : 19 Pages
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ISL12058
Protocol Conventions
Data states on the SDA line can change only during SCL LOW
periods. SDA state changes during SCL HIGH are reserved for
indicating START and STOP conditions (see Figure 7). On
power-up of the ISL12058, the SDA pin is in the input mode.
All I2C interface operations must begin with a START condition,
which is a HIGH to LOW transition of SDA while SCL is HIGH.
The ISL12058 continuously monitors the SDA and SCL lines
for the START condition and does not respond to any
command until this condition is met (see Figure 7). A START
condition is ignored during the power-up sequence.
All I2C interface operations must be terminated by a STOP
condition, which is a LOW to HIGH transition of SDA while SCL
is HIGH (see Figure 7). A STOP condition at the end of a read
operation or at the end of a write operation to memory only
places the device in its standby mode.
An acknowledge (ACK) is a software convention used to
indicate a successful data transfer. The transmitting device,
either master or slave, releases the SDA bus after transmitting
8 bits. During the ninth clock cycle, the receiver pulls the SDA
line LOW to acknowledge the reception of the 8 bits of data
(see Figure 8).
The ISL12058 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
ISL12058 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.
SCL
SDA
START
DATA
DATA
DATA
STABLE CHANGE STABLE
STOP
FIGURE 7. 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
FIGURE 8. ACKNOWLEDGE RESPONSE FROM RECEIVER
ACK
13
FN6756.0
June 15, 2009
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