ADT7420 Analog Devices, ADT7420 Datasheet - Page 13

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

Preliminary Technical Data
REGISTERS
The ADT7420 contains 14 registers:
•
•
•
•
•
•
All registers are eight bits wide. The temperature value registers,
the status register, and the ID register are read-only. The software
reset is a write-only register. On power-up, the address pointer
register is loaded with 0x00 and points to the temperature value
register MSB.
Table 6. ADT7420 Registers
Register
Address
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x2F
Table 8. Temperature Value MSB Register (Register Address 0x00)
Bit
[8:14]
15
Table 9. Temperature Value LSB Register (Register Address 0x01)
Bit
0
1
2
[3:7]
Nine temperature registers
A status register
An ID register
A configuration register
An address pointer register
A software reset
Default
Value
0
0
0
00000
Description
Temperature value most significant byte
Temperature value least significant byte
Status
Configuration
T
T
T
T
T
T
T
ID
Software reset
HIGH
HIGH
LOW
LOW
CRIT
CRIT
HYST
Default Value
0000000
0
setpoint most significant byte
setpoint least significant byte
setpoint most significant byte
setpoint least significant byte
setpoint most significant byte
setpoint least significant byte
setpoint
Type
R
R
R
R
Name
T
T
T
Temp
LOW
HIGH
CRIT
flag/LSB2
flag/LSB0
flag/LSB1
Type
R
R
Description
Flags a T
resolution). When the temperature value is below T
Contains the Least Significant Bit 0 of the 15-bit temperature value if the configuration
register, Register Address 0x03[7] = 1 (16-bit resolution).
Flags a T
resolution). When the temperature value is above T
Contains the Least Significant Bit 1 of the 15-bit temperature value if the configuration
register, Register Address 0x03[7] = 1 (16-bit resolution).
Flags a T
resolution). When the temperature value exceeds T
Contains the Least Significant Bit 2 of the 15-bit temperature value if the configuration
register, Register Address 0x03[7] = 1 (16-bit resolution).
Temperature value in twos complement format.
Name
Temp
Sign
Power-On
Default
0x00
0x00
0x00
0x00
0x20 (64°C)
0x00 (64°C)
0x05 (10°C)
0x00 (10°C)
0x49 (147°C)
0x80 (147°C)
0x05 (5°C)
0xCX
0xXX
LOW
HIGH
CRIT
event if the configuration register, Register Address 0x03[7] = 0 (13-bit
event if the configuration register, Register Address 0x03[7] = 0 (13-bit
event if the configuration register, Register Address 0x03[7] = 0 (13-bit
Description
Temperature value in twos complement format
Sign bit, indicates if the temperature value is negative or positive
Rev. PrA | Page 13 of
ADDRESS POINTER REGISTER
This register is always the first register written to during a write
to the ADT7420. It should be set to the address of the register
to which the write or read transaction is intended. Table 7
shows the register address of each register on the ADT7420.
The default value of the address pointer register is 0x00.
Table 7. Address Pointer Register
P7
ADD7
TEMPERATURE VALUE REGISTERS
The temperature value most significant byte (MSB) and tem-
perature value least significant byte (LSB) registers store the
temperature measured by the internal temperature sensor.
The temperature is stored in twos complement format with
the MSB being the temperature sign bit. When reading from
these registers, the eight MSBs (Bit 7 to Bit 15) are read first
from Register Address 0x00 and then the eight LSBs (Bit 0 to
Bit 7) are read from Register Address 0x01. Only the tempera-
ture value most significant byte (Register Address 0x00) needs to
be loaded into the address pointer register because the address
pointer autoincrements to the temperature value least signifi-
cant byte address (Register Address 0x01).
Bit 0 to Bit 2 are event alarm flags for T
the ADC is configured to convert the temperature to a 16-bit
digital value, then Bit 0 to Bit 2 are no longer used as flag bits
and are instead used as the LSB bits for the extended digital value.
P6
ADD6
P5
ADD5
CRIT
LOW
HIGH
P4
ADD4
, this bit it set to 1.
, this bit it set to 1.
, this bit it set to 1.
P3
ADD3
CRIT
www.DataSheet4U.com
, T
P2
ADD2
HIGH
, and T
ADT7420
P1
ADD1
LOW
. When
P0
ADD0