ADT7460ARQZ-RL7 ONSEMI [ON Semiconductor], ADT7460ARQZ-RL7 Datasheet - Page 17

• Manufacturer Part Number: ADT7460ARQZ-RL7
• Description: dBCOOL Remote Thermal Monitor and Fan Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Overtemperature Events
channels can be detected and dealt with automatically in
automatic fan speed control mode. Registers 0x6A to 0x6C
are the THERM limits. When a temperature exceeds its
THERM limit, all fans run at 100% duty cycle. The fans
continue running at 100% until the temperature drops below
THERM – Hysteresis. (This can be disabled by setting the
BOOST bit in Configuration Register 3, Bit 2, Register
0x78). The hysteresis value for that THERM limit is the
value programmed into Registers 0x6D and 0x6E
(hysteresis registers). The default hysteresis value is 4°C.
Additional ADC Functions for Temperature Measurement
ADT7460 to offer the systems designer increased flexibility.
Turn−Off Averaging
register, 16 readings have actually been made internally and
the results averaged before being placed into the value
register. Sometimes it may be necessary to take a very fast
measurement, for example, of CPU temperature. Setting
Bit 4 of Configuration Register 2 (Reg. 0x73) turns
averaging off. This takes a reading every 15.5 ms. Each
remote temperature measurement takes 4 ms and the local
temperature measurement takes 1.4 ms.
Single−Channel ADC Conversions
places the ADT7460 into single−channel ADC conversion
mode. In this mode, the ADT7460 can be made to read a
single temperature channel only. The appropriate ADC
channel is selected by writing to Bits <7:5> of the TACH1
minimum high byte register (Reg. 0x55).
Table 13. Temperature Measurement Limit Registers
Overtemperature events on any of the temperature
THERM LIMIT
TEMPERATURE
FANS
A number of other functions are available on the
For each temperature measurement read from a value
Setting Bit 6 of Configuration Register 2 (Reg. 0x73)
Register
0x4E
0x4F
0x50
0x51
0x52
0x53
Figure 27. THERM Limit Operation
Remote 1 temperature high limit
Remote 2 temperature high limit
Remote 1 temperature low limit
Remote 2 temperature low limit
Local temperature high limit
Local temperature low limit
Description
100%
HYSTERESIS (5C)
Default
0x81
0x7F
0x81
0x7F
0x81
0x7F
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ADT7460
17
Limits, Status Registers, and Interrupts
Limit Values
ADT7460 are high and low limits. These can form the basis
of system status monitoring: a status bit can be set for any
out−of−limit condition and detected by polling the device.
Alternatively, SMBALERT interrupts can be generated to
flag a processor or micro controller of out−of−limit
conditions.
8−Bit Limits
Table 14. Configuration Register 2 (Reg. 0x73)
Table 15. TACH1 Minimum High Byte (Reg. 0x55)
Table 16. Voltage Limit Registers
Table 17. Temperature Limit Registers
Table 18. THERM Timer Limit Registers
<7:5>
Associated with each measurement channel on the
The following is a list of 8−bit limits on the ADT7460.
<4>
<6>
Register
Register
Register
Bit
Bit
0x4E
0x4F
0x6A
0x6B
0x6C
0x7A
0x44
0x45
0x48
0x49
0x50
0x51
0x52
0x53
1: Averaging Off
1: Single−Channel Convert Mode
Selects ADC channel for single−channel convert
mode
Value
101
110
111
Remote 1 temperature high limit
Remote 2 temperature high limit
Remote 1 temperature low limit
Remote 2 temperature low limit
Local temperature high limit
Local temperature low limit
Remote 1 THERM limit
Remote 2 THERM limit
Local THERM limit
THERM timer limit
2.5 V high limit
2.5 V low limit
V
V
Description
Description
Description
CC
CC
high limit
Description
Description
low limit
Channel Selected
Remote 1 temp
Remote 2 temp
Local temp
Default
Default
Default
0xFF
0xFF
0x00
0x00
0x81
0x7F
0x64
0x81
0x7F
0x64
0x81
0x7F
0x64
0x00