ADT7476ARQH ONSEMI [ON Semiconductor], ADT7476ARQH Datasheet - Page 11

• Manufacturer Part Number: ADT7476ARQH
• Description: dBCOOL Remote Thermal Controller and Voltage Monitor
• Manufacturer: ONSEMI [ON Semiconductor]

serial bus in one operation. However, it is not possible to mix
read and write in one operation because the type of operation
is determined at the beginning and cannot subsequently be
changed without starting a new operation. In the ADT7476,
write operations contain either one or two bytes, and read
operations contain one byte.
data from it, the address pointer register must be set so the
correct data register is addressed. Then, data can be written
into that register or read from it. The first byte of a write
operation always contains an address stored in the address
pointer register. If data is to be written to the device, then the
write operation contains a second data byte that is written to
the register selected by the address pointer register.
address is sent over the bus, and then R/W is set to 0. This
is followed by two data bytes. The first data byte is the
address of the internal data register to be written to, which
is stored in the address pointer register. The second data byte
is the data to be written to the internal data register.
Figure 18. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register
Any number of bytes of data can be transferred over the
To write data to one of the device data registers or read
This write operation is illustrated in Figure 18. The device
pulse to assert a stop condition. In read mode, the
master device overrides the acknowledge bit by
pulling the data line high during the low period
before the ninth clock pulse. This is known as no
acknowledge. The master then takes the data line
low during the low period before the 10
pulse, and then high during the 10
assert a stop condition.
START BY MASTER
SDA
SCL
SDA
SCL
START BY MASTER
1
0
1
0
1
SERIAL BUS ADDRESS BYTE
1
Figure 19. Writing to the Address Pointer Register Only
0
SERIAL BUS ADDRESS BYTE
0
1
FRAME 1
th
1
FRAME 1
1
clock pulse to
th
SDA (CONTINUED)
1
SCL (CONTINUED)
A1
clock
A1
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A0
A0
R/W
11
ACK. BY ADT7476
R/W
9
ACK. BY ADT7476
When reading data from a register, there are two 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.
protocols, the ADT7476 also supports the read byte protocol.
See Intel’s System Management Bus Specifications
Revision 2 for more information.
succession, the master can send a repeat start condition
instead of a stop condition to begin a new operation.
It is possible to read a data byte from a data register
In addition to supporting the send byte and receive byte
If several read or write operations must be performed in
D7
9
1
D7
1
1. If the ADT7476’s address pointer register value is
2. If the address pointer register is already known to
unknown, or not the desired value, then it must
first be set to the correct value before data can be
read from the desired data register. This is done by
performing a write to the ADT7476 as before, but
only the data byte containing the register address
is sent, because no data is written to the register
(see Figure 19).
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 (see
Figure 20.)
be at the desired address, data can be read from the
corresponding data register without first writing to
the address pointer register (see Figure 20).
D7
D6
1
D6
ADDRESS POINTER REGISTER BYTE
D6
D5
D5
ADDRESS POINTER REGISTER BYTE
D5
D4
D4
DATA BYTE
FRAME 3
FRAME 2
D4
D3
D3
FRAME 2
D3
D2
D2
D2
D1
D1
ACK. BY ADT7476
ACK. BY MASTER MASTER
D1
D0
D0
D0
ACK. BY ADT7476
9
9
9
STOP BY
MASTER
STOP BY