ADT7468 Analog Devices, Inc., ADT7468 Datasheet - Page 50

• Manufacturer Part Number: ADT7468
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

ADT7468
STEP 7: T
T
temperature channel. Above this temperature, a component
such as the CPU or VRM might be operating beyond its safe
operating limit. When the temperature measured exceeds
T
to provide critical system cooling.
THERM
THERM
100
100
Figure 67. T
90
80
70
60
50
40
30
20
10
90
80
70
60
50
40
30
20
10
, all fans are driven at 100% PWM duty cycle (full speed)
0
0
is the absolute maximum temperature allowed on a
0
0
THERM
10
10
RANGE
20
20
FOR TEMPERATURE CHANNELS
and % Fan Speed Slopes for VRM, Ambient, and
CPU Temperature Channels
TEMPERATURE ABOVE T
TEMPERATURE ABOVE T
30
30
40
40
50
50
60
60
MIN
70
70
MIN
80
80
90
90
100
100
Rev. A | Page 50 of 84
The fans remain running at 100% until the temperature drops
below T
programmed into the hysteresis Registers 0x6D and 0x6E. The
default hysteresis value is 4°C.
The T
operating temperature of the system. Because exceeding any
T
effects. Ultimately, this limit should be set up as a fail-safe, and
one should ensure that it is not exceeded under normal system
operating conditions.
Note that the T
speed regardless of how automatic fan control settings are
configured. This allows some flexibility, because a T
can be selected based on its slope, while a hard limit (such as
70°C), can be programmed as T
the fan reaches full speed) by setting T
example, 70°C).
THERM Registers
Reg. 0x6A, Remote 1 THERM limit = 0xA4 (100°C default)
Reg. 0x6B, Local THERM limit = 0xA4 (100°C default)
Reg. 0x6C, Remote 2 THERM limit = 0xA4 (100°C default)
Hysteresis Registers
Reg. 0x6D, Remote 1, local hysteresis register
<7:4>, Remote 1 temperature hysteresis (4°C default)
<3:0>, Local temperature hysteresis (4°C default)
Reg. 0x6E, Remote 2 Temperature Hysteresis Register
<7:4>, Remote 2 temperature hysteresis (4°C default)
Because each hysteresis setting is four bits, hysteresis values are
programmable from 1°C to 15°C. It is recommended that
hysteresis values never be programmed to 0°C, because this
disables hysteresis. In effect, this would cause the fans to cycle
between normal speed and 100% speed, creating unsettling
acoustic noise.
THERM
THERM
limit runs all fans at 100%, it has very negative acoustic
THERM
limit should be considered the maximum worst-case
minus hysteresis, where hysteresis is the number
THERM
limits are nonmaskable and affect the fan
MAX
(the temperature at which
THERM
to that limit (for
RANGE
value