Datasheet

ADT7408
Rev. 0 | Page 13 of 24
TEMPERATURE TRIP POINT REGISTERS
There are three temperature trip point registers. They are the alarm temperature upper boundary trip register, the alarm temperature
lower boundary trip register, and the critical temperature trip register.
Alarm Temperature Upper Boundary Trip Register (Read/Write)
The value is the upper threshold temperature value for alarm mode. The data format is twos complement with one LSB = 0.25
o
C.
RFU (reserved for future use) bits are not supported and always report 0. Interrupts respond to the programmed boundary values.
If boundary values are being altered in-system, the user should turn off interrupts until a known state can be obtained to avoid
superfluous interrupt activity. The format of this register is shown in the following bit map:
Sign
MSB
LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 Alarm window upper boundary temperature RFU RFU
Alarm Temperature Lower Boundary Trip Register (Read/Write)
The value is the lower threshold temperature value for alarm mode. The data format is twos complement with one LSB = 0.25
o
C.
RFU bits are not supported and always report 0. Interrupts respond to the programmed boundary values. If boundary values are being
altered in-system, the user should turn off interrupts until a known state can be obtained to avoid superfluous interrupt activity. The
format of this register is shown in the following bit map:
Sign
MSB
LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 Alarm window upper boundary temperature RFU RFU
Critical Temperature Trip Register (Read/Write)
The value is the critical temperature. The data format is twos complement with one LSB = 0.25
o
C. RFU bits are not supported and always
report 0. The format of this register is shown in the following bit map:
Sign
MSB
LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 Critical temperature trip point RFU RFU
Temperature Value Register (Read Only)
This 16-bit, read-only register stores the trip status and the temperature measured by the internal temperature sensor, as shown in Table 9.
The temperature is stored in 13-bit, twos complement format with the MSB being the temperature sign bit and the 12 LSBs representing
temperature. One LSB = 0.0625
o
C. The most significant bit has a resolution of 128
o
C.
When reading from this register, the eight MSBs (Bit D15 to Bit D8) are read first, and then the eight LSBs (Bit D7 to Bit D0) are read.
The trip status bits represent the internal temperature trip detection and are not affected by the status of the event or configuration bits,
for example, event output control, clear event. If both above and below are 0, then the current temperature is exactly within the alarm
window boundaries, as defined in the configuration register. The format and descriptions are shown in
Table 9 and the following bit map:
Sign
MSB
LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Above
critical
trip
Above
alarm
window
Below
alarm
window Temperature