ADT7470 Analog Devices, Inc., ADT7470 Datasheet - Page 14

• Manufacturer Part Number: ADT7470
• Description: Temperature Sensor Hub And Fan Controller
• Manufacturer: Analog Devices, Inc.

ADT7470
INTERRUPT FUNCTIONALITY AND STATUS REGISTERS
LIMIT VALUES
Associated with each measurement channel on the ADT7470
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 be detected by polling the device. Alternatively,
SMBALERT interrupts can be generated to automatically flag
a service processor or microcontroller for out-of-limit
conditions as they occur.
8-BIT LIMITS
Table 7 lists the 8-bit limits on the ADT7470.
Table 7. Temperature Limit Registers (8-Bit Limits)
Register Address
0x44
0x45
0x46
0x47
0x48
0x49
0x4A
0x4B
0x4C
0x4D
0x4E
0x4F
0x50
0x51
0x52
0x53
0x54
0x55
0x56
0x57
Description
Temperature 1 Low Limit
Temperature 1 High Limit
Temperature 2 Low Limit
Temperature 2 High Limit
Temperature 3 Low Limit
Temperature 3 High Limit
Temperature 4 Low Limit
Temperature 4 High Limit
Temperature 5 Low Limit
Temperature 5 High Limit
Temperature 6 Low Limit
Temperature 6 High Limit
Temperature 7 Low Limit
Temperature 7 High Limit
Temperature 8 Low Limit
Temperature 8 High Limit
Temperature 9 Low Limit
Temperature 9 High Limit
Temperature 10 Low Limit
Temperature 10 High Limit
Default
0x81
0x7F
0x81
0x7F
0x81
0x7F
0x81
0x7F
0x81
0x7F
0x81
0x7F
0x81
0x7F
0x81
0x7F
0x81
0x7F
0x81
0x7F
Rev. B | Page 14 of 40
16-BIT LIMITS
The fan tach measurements are 16-bit results. The fan tach
limits are also 16 bits, consisting of two bytes: a high byte and
low byte. On the ADT7470 it is possible to set both high and
low speed fan limits for overspeed and underspeed or stall con-
ditions. Be aware that, because the fan tach period is actually
being measured, exceeding the limit by 1 indicates a slow or
stalled fan. Likewise, exceeding the high speed limit by 1
generates an overspeed condition.
Table 8. Fan Underspeed Limit Registers
Register Address
0x58
0x59
0x5A
0x5B
0x5C
0x5D
0x5E
0x5F
Table 9. Fan Overspeed Limit Registers
Register Address
0x60
0x61
0x62
0x63
0x64
0x65
0x66
0x67
Description
Tach 1 Max Low Byte
Tach 1 Max High Byte
Tach 2 Max Low Byte
Tach 2 Max High Byte
Tach 3 Max Low Byte
Tach 3 Max High Byte
Tach 4 Max Low Byte
Tach 4 Max High Byte
Description
Tach 1 Min Low Byte
Tach 1 Min High Byte
Tach 2 Min Low Byte
Tach 2 Min High Byte
Tach 3 Min Low Byte
Tach 3 Min High Byte
Tach 4 Min Low Byte
Tach 4 Min High Byte
Default
0xFF
0xFF
0xFF
0xFF
0xFF
0xFF
0xFF
0xFF
Default
0x00
0x00
0x00
0x00
0x00
0x00
0x00
0x00