ADT7460ARQZ-RL7 ONSEMI [ON Semiconductor], ADT7460ARQZ-RL7 Datasheet - Page 11

• Manufacturer Part Number: ADT7460ARQZ-RL7
• Description: dBCOOL Remote Thermal Monitor and Fan Controller
• Manufacturer: ONSEMI [ON Semiconductor]

possibilities:
without first writing to the address pointer register if the
address pointer register is already at the correct value.
However, it is not possible to write data to a register without
writing to the address pointer register because the first data
byte of a write is always written to the address pointer
register.
as the default value 01011(A1) (A0), where A1 and A0 are
set by the address select mode function previously defined.
protocols, the ADT7460 also supports the Read Byte
Figure 17. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register
When reading data from a register, there are two
It is possible to read a data byte from a data register
In Figure 17 and Figure 19, the serial bus address is shown
In addition to supporting the Send Byte and Receive Byte
♦
♦
unknown or not the desired value, it is first
necessary to set it to the correct value before data
can be read from the desired data register. This is
done by performing a write to the ADT7460 as
before, but only the data byte containing the register
address is sent because data is not to be written to
the register. This is shown in Figure 18.
A read operation is then performed, consisting of the
serial bus address, R/W bit set to 1, followed by the
data byte read from the data register. This is shown
in Figure 19.
at the desired address, data can be read from the
corresponding data register without first writing to
the address pointer register, so Figure 18 can be
omitted.
If the ADT7460’s address pointer register value is
If the address pointer register is known to be already
SDA
SCL
START BY
MASTER
1
0
1
0
SERIAL BUS ADDRESS
1
FRAME 1
BYTE
SDA (CONTINUED)
1
SCL (CONTINUED)
A1
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A0
ADT7460
R/W
ADT7460
ACK. BY
11
D7
9
1
protocol (see System Management Bus specifications
Rev. 2.0 for more information).
in succession, the master can send a repeat start condition
instead of a stop condition to begin a new operation.
Write Operations
different types of read and write operations. The ones used
in the ADT7460 are discussed below. The following
abbreviations are used in the diagrams:
The ADT7460 uses the following SMBus write protocols:
Send Byte
command byte to a slave device as follows:
If it is required to perform several read or write operations
The SMBus specification defines several protocols for
In this operation, the master device sends a single
D7
D6
1
S—start
P—stop
R—read
W—write
A—acknowledge
A—no acknowledge
1. The master device asserts a start condition on SDA.
2. The master sends the 7−bit slave address followed
3. The addressed slave device asserts ACK on SDA.
4. The master sends the register address.
5. The slave asserts ACK on SDA.
6. The master asserts a stop condition on SDA and
by the write bit (low).
the transaction ends.
D6
D5
ADDRESS POINTER REGISTER BYTE
D5
D4
FRAME 3
DATA
BYTE
D4
D3
FRAME 2
D3
D2
D2
D1
D1
D0
ADT7460
ACK. BY
D0
9
ADT7460
ACK. BY
STOP BY
MASTER
9