ADT7467 Analog Devices, Inc., ADT7467 Datasheet - Page 37

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

Dynamic T
Dynamic T
control loop by adjusting the T
performance and measured temperature. Therefore, instead of
designing for the worst case, the system thermals can be defined
as operating zones. ADT7467 can self-adjust its fan control loop
to maintain either an operating zone temperature or a system
target temperature. For example, users can specify that the
ambient temperature in a system be maintained at 50°C. If the
temperature is below 50°C, the fans might not run or might run
very slowly. If the temperature is higher than 50°C, the fans
might throttle up.
The challenge presented by any thermal design is finding the
right settings to suit the system’s fan control solution. This can
involve designing for the worst case, followed by weeks of
system thermal characterization, and finally fan acoustic
optimization (for psychoacoustic reasons). Optimizing the
automatic fan control mode involves characterizing the system
to determine the best T
loop and the PWM
speed setting. Using the ADT7467’s dynamic T
mode, however, shortens the characterization time and
alleviates tweaking the control loop settings because the device
can self-adjust during system operation.
Dynamic T
operating zone temperatures required for the system.
Associated with this control mode are three operating point
registers, one for each temperature channel. This allows the
system thermal solution to be broken down into distinct
thermal zones. For example, CPU operating temperature is
70°C, VRM operating temperature is 80°C, and ambient
operating temperature is 50°C. The ADT7467 dynamically
alters the control solution to maintain each zone temperature as
closely as possible to its target operating point.
Operating Point Registers
Reg. 0x33, Remote 1 operating point = 0xA4 (100°C default)
Reg. 0x34, local operating point = 0xA4 (100°C default)
Reg. 0x35, Remote 2 operating point = 0xA4 (100°C default)
MIN
MIN
MIN
control mode builds on the basic automatic fan
control mode is operated by specifying the
Control Overview
MIN
value that produces the quietest fan
MIN
and T
MIN
RANGE
value based on system
settings for the control
MIN
control
Rev. A| Page 37 of 80
Figure 52 shows an overview of the parameters that affect the
operation of the dynamic T
Table 14 provides a brief description of each parameter.
Table 14. T
Parameter
T
T
T
Operating
T
T
Dynamic T
Because the dynamic T
the automatic fan control mode, program the automatic fan
control mode parameters as described in Step 1 to Step 8, and
then proceed with dynamic T
LOW
HIGH
MIN
THERM
RANGE
Point
T
LOW
MIN
MIN
T
MIN
Control Loop Parameters
Control Programming
Description
If the temperature drops below the T
error flag is set in a status register and an
SMBALERT interrupt can be generated.
If the temperature exceeds the T
error flag is set in a status register and an
SMBALERT interrupt can be generated.
The temperature at which the fan turns on in
automatic fan speed control mode.
The target temperature for a particular
temperature zone. The ADT7467 attempts to
maintain system temperature at approximately
the operating point by adjusting the T
parameter of the control loop.
If the temperature exceeds this critical limit, the
fans can run at 100% for maximum cooling.
Programs the PWM duty cycle vs. temperature
control slope.
Figure 52. Dynamic T
OPERATING
POINT
MIN
control mode is a basic extension of
MIN
T
HIGH
MIN
control loop.
T
control mode programming.
THERM
MIN
Control Loop
T
RANGE
TEMPERATURE
HIGH
ADT7467
limit, an
LOW
MIN
limit, an