ADT7420 Analog Devices, ADT7420 Datasheet - Page 19

• Manufacturer Part Number: ADT7420
• Description: 16-Bit Digital I2C Temperature Sensor
• Manufacturer: Analog Devices

Preliminary Technical Data
READING DATA
Reading data from the ADT7420 is done in a single data byte
operation for the configuration register, the status register,
the T
operation is needed for the temperature value register, T
setpoint
register. Reading back the contents of an 8-bit register similar
to the configuration register is shown in Figure 16. Reading
back the contents of the temperature value register is shown
in Figure 17.
Reading back from any register first requires a single-byte write
operation to the address pointer register to set up the address of
the register that is going to be read from. In the case of reading
back from the 2-byte registers, the address pointer automatically
increments from the MSB register address to the LSB register
address.
To read from another register, execute another write to the
address pointer register to set up the relevant register address.
Thus, block reads are not possible, that is, there is no I
pointer autoincrement except when reading back from a 16-bit
register. If the address pointer register has previously been set
up with the address of the register that is going to receive a read
command, there is no need to repeat a write operation to set up
the register address again.
HYST
register, T
register, and the ID register. A two data byte read
REPEAT START
SDA
SCL
SDA
SCL
BY MASTER
START BY
MASTER
LOW
setpoint
1
1
1
1
0
0
register, and the T
SERIAL BUS ADDRESS
0
0
SERIAL BUS ADDRESS
1
FRAME 3
1
FRAME 1
BYTE
BYTE
Figure 16. Reading Back Data from the Configuration Register
0
0
CRIT
A1
A1
setpoint
2
C address
A0
A0
HIGH
Rev. PrA | Page 19 of
R/W
R/W
ADT7420
ACK. BY
ADT7420
ACK. BY
9
9
D7
P7
1
1
RESET
To reset the ADT7420 without having to reset the entire I
an explicit reset command is provided. This uses a particular
address pointer word as a command word to reset the part and
upload all default settings. The ADT7420 does not respond to
the I
values upload for approximately 200 µs.
The reset command address word is 0x2F.
GENERAL CALL
When a master issues a slave address consisting of seven 0s with
the eighth bit (R/ W
address. The general call address is for addressing every device
connected to the I
and reads in the following data byte.
If the second byte is 0x06, the ADT7420 is reset, completely
uploading all default values. The ADT7420 does not respond
to the I
default values upload for approximately 200 µs.
The ADT7420 does not acknowledge any other general call
commands.
D6
P6
2
DATA BYTE FROM CONFIGURATION
C bus commands (do not acknowledge) during the default
ADDRESS POINTER REGISTER BYTE
2
C bus commands (do not acknowledge) while the
D5
P5
P4
D4
REGISTER
FRAME 4
FRAME 2
2
C bus. The ADT7420 acknowledges this address
D3
P3
bit) set to 0, this is known as the general call
P2
D2
P1
D1
NO ACK. BY
D0
P0
ADT7420
MASTER
ACK. BY
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9
9
STOP BY
MASTER
ADT7420
2
C bus,