Datasheet

ADT7408
Rev. 0 | Page 10 of 24
REGISTERS
The ADT7408 contains 16 accessible registers, shown in Table 5.
The address pointer register is the only register that is eight bits;
the other registers are 16 bits wide. On power-up, the address
pointer register is loaded with 0x00 and points to the capability
register.
Table 5. Registers
Pointer
Address
Name
Power-On
Default
Read/Write
Not
Applicable
Address Pointer
Register
0x00 Write
0x00 Capability Register 0x001D Read
0x01 Configuration Register 0x0000 Read/Write
0x02
Alarm Temperature
Upper Boundary
Trip Register
0x0000 Read/Write
0x03
Alarm Temperature
Lower Boundary
Trip Register
0x0000 Read/Write
0x04
Critical Temperature
Trip Register
0x0000 Read/Write
0x05
Temperature Value
Register
Undefined Read
0x06
Manufacturer ID
Register
0x11D4 Read
0x07
Device ID/Revision
Register
0x080X Read
0x08 to 0x0F
Vendor-Defined
Registers
0x0000 Reserved
ADDRESS POINTER REGISTER (WRITE ONLY)
This 8-bit write only register selects which of the 16-bit registers
is accessed in subsequent read/write operations. Address space
between 0x08 and 0x0F is reserved for factory usage.
MSB LSB
D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 0
Register
select
Register
select
Register
select
Register
select
Table 6. Address Pointer Selected Registers
D2 D1 D0 Register Selected
0 0 0 Capability Register
0 0 1 Configuration Register
0 1 0
Alarm Temperature Upper Boundary Trip
Register
0 1 1
Alarm Temperature Lower Boundary Trip
Register
1 0 0 Critical Temperature Trip Register
1 0 1 Temperature Value Register
1 1 0 Manufacturer ID Register
1 1 1 Device ID/Revision Register
CAPABILITY REGISTER (READ ONLY)
This 16-bit, read-only register indicates the capabilities of the
thermal sensor, as shown in
Table 7 and the following bit map.
Note that RFU means reserved for future use.
MSB LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
RFU RFU RFU RFU RFU RFU RFU RFU RFU RFU RFU TRES1 TRES0
Wider
range
Higher
precision
Alarm/Critical
trips
Table 7. Capability Mode Description
Bit Function
Basic capability
D0 Trips Capability
D0
Alarm/Critical Trips
1 Alarm and critical trips capability
Accuracy
D1 Accuracy Capability
D1
Higher Precision
0 Default accuracy ±2°C over the active range and ±3°C over the monitor range
Wider range
D2 Temperature Range Capability
D2
Wider Range
1 Can read temperature below 0°C and set sign bit accordingly (default)
Temperature resolution
[D4:D3] Temperature Resolution
01 0.25°C LSB
[D4:D3]
Temperature Resolution
11 0.0625°C LSB (default)
[D15:D5] Reserved for future use; must be 0