ADT7467 Analog Devices, Inc., ADT7467 Datasheet - Page 71

• Manufacturer Part Number: ADT7467
• Description: Dbcool Remote Thermal Monitor And Fan Controller
• Manufacturer: Analog Devices, Inc.

Table 39. THERM Limit Registers
Register Address
0x6A
0x6B
0x6C
1
2
Table 40. Temperature/T
Register Address
0x6D
<3:0>
<7:4>
0x6E
<7:4>
1
2
Table 41. XNOR Tree Test Enable
Register Address
0x6F
<0>
<7:1>
1
Table 42. Remote 1 Temperature Offset
Register Address
0x70
<7:0>
1
If any temperature measured exceeds its THERM limit, all PWM outputs drive their fans at 100% duty cycle. This is a fail-safe mechanism incorporated to cool the
system in the event of a critical overtemperature. It also ensures some level of cooling in the event that software or hardware locks up. If set to 0x80, this feature is
disabled. The PWM output remains at 100% until the temperature drops below THERM Limit – Hysteresis. If the THERM pin is programmed as an output, then
exceeding these limits by 0.25°C can cause the THERM pin to assert low as an output.
These registers become read-only registers when the Configuration Register 1 lock bit is set to 1. Any subsequent attempts to write to these registers fail.
Each 4-bit value controls the amount of temperature hysteresis applied to a particular temperature channel. Once the temperature for that channel falls below its T
value, the fan remains running at PWM
The hysteresis value chosen also applies to that temperature channel if its THERM limit is exceeded. If the THERM limit is exceeded, the PWM output being controlled
goes to 100% and remains at 100% until the temperature drops below THERM – hysteresis. For acoustic reasons, it is recommended that the hysteresis value not be
programmed to less than 4°C. Setting the hysteresis value lower than 4°C causes the fan to switch on and off regularly when the temperature is close to T
These registers become read-only registers when the Configuration Register 1 lock bit is set to 1. Any subsequent attempts to write to these registers fail.
This register becomes a read-only register when the Configuration Register 1 lock bit is set to 1. Any subsequent attempts to write to this register fail.
This register becomes a read-only register when the Configuration Register 1 lock bit is set to 1. Any subsequent attempts to write to this register fail.
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Hysteresis Registers
R/W
Read/write
HYSL
HYSR1
Read/write
HYSR2
R/W
Read/write
Read/write
Read/write
R/W
Read/write
XEN
Reserved
R/W
Read/write
Read/write
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duty cycle until the temperature = T
1
2
2
1
1
1
Description
Remote 1 THERM limit.
Local THERM limit.
Remote 2 THERM limit.
Description
Remote 1 and local temperature hysteresis.
Local temperature hysteresis. 0°C to 15°C of
hysteresis can be applied to the local temperature
AFC and dynamic T
Remote 1 temperature hysteresis. 0°C to 15°C of
hysteresis can be applied to the Remote 1
temperature AFC and dynamic T
Remote 2 temperature hysteresis.
Local temperature hysteresis. 0°C to 15°C of
hysteresis can be applied to the local temperature
AFC and dynamic T
Description
XNOR tree test enable register.
If the XEN bit is set to 1, the device enters the XNOR
tree test mode. Clearing the bit removes the device
from the XNOR tree test mode.
Unused. Do not write to these bits.
Description
Remote 1 temperature offset.
Allows a twos complement offset value to be
automatically added to or subtracted from the
Remote 1 temperature reading. This is to
compensate for any inherent system offsets such as
PCB trace resistance. LSB value = 0.5°C.
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– hysteresis. Up to 15°C of hysteresis can be assigned to any temperature channel.
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control loops.
control loops.
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control loops.
Power-On Default
0x64 (100°C)
0x64 (100°C)
0x64 (100°C)
Power-On Default
0x44
0x40
Power-On Default
0x00
Power-On Default
0x00
ADT7467
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