ADT7463 Analog Devices, ADT7463 Datasheet - Page 15

• Manufacturer Part Number: ADT7463
• Description: Dbcool Thermal Management Controller And Voltage Monitor
• Manufacturer: Analog Devices

The design usually accounts for worst-case conditions
in all of these cases.
Note, however, that the actual system is almost never
operated at worst-case conditions.
The alternative to designing for the worst case is to use
the dynamic T
DYNAMIC T
Dynamic T
matic
value based on system performance and measured tem-
perature. Why is this important?
Instead of designing for the worst case, the system
thermals can be defined as “operating zones.” The
ADT7460/ADT7463 will self-adjust its fan control loop to
maintain an operating zone temperature or system tar-
get temperature. For example, you can specify that the
ambient temperature in a system should be maintained
at 50°C. If the temperature is below 50°C, the fans may not
need to run or may run very slowly. If the temperature is
higher than 50°C, the fans need to throttle up. How is this
different from the automatic fan control mode?
The challenge presented by any thermal design is find-
ing the right settings to suit the system’s fan control
solution. This can involve designing for the worst case
(as previously outlined), followed by weeks of system
thermal characterization, and finally fan acoustic optimi-
zation (for psycho-acoustic reasons). Getting the most
benefit from the automatic fan control mode involves
characterizing the system to find the best T
T
PWM
the ADT7460/ADT7463’s dynamic T
shortens the characterization time and alleviates tweak-
ing the control loop settings because the device can
self-adjust during system operation.
DYNAMIC T
The dynamic T
ing the “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, e.g., CPU oper-
ating temperature = 70°C, VRM operating temperature =
80°C, ambient operating temperature = 50°C. The
ADT7460/ADT7463 will dynamically alter the control
REV. 0
RANGE
MIN
settings for the control loop, and the best
fan
value for the quietest fan speed setting. Using
MIN
MIN
MIN
control
Control mode builds upon the basic auto-
MIN
CONTROL—OVERVIEW
CONTROL—THE SPECIFICS
MIN
control function.
control mode is operated by specify-
loop
by
adjusting
MIN
control mode
the
MIN
T
and
MIN
–15–
solution to maintain each zone temperature as closely
as possible to their target operating points.
OPERATING POINT REGISTERS
Reg. 0x33 Remote 1 Operating Point = 0x64 (100°C)
Reg. 0x34 Local Temp Operating Point = 0x64 (100°C)
Reg. 0x35 Remote 2 Operating Point = 0x64 (100°C)
Figure 20 shows an overview of the parameters that
affect the operation of the dynamic T
brief description of each parameter follows:
1. T
2. T
3. T
4. Operating Point. This temperature defines the target
5. T
6. T
DYNAMIC T
Since the dynamic T
of the automatic fan control mode, the automatic fan con-
trol mode parameters should be programmed first. Follow
the seven steps in the Automatic Fan Control section of the
ADT7460/ADT7463 data sheet before proceeding with
dynamic T
error flag is set in a status register and an SMBALERT
interrupt can be generated.
flag gets set in a status register and an SMBALERT
interrupt can be generated.
under automatic fan speed control.
temperature or optimal operating point for a
particular temperature zone. The ADT7460/ADT7463
attempt to maintain system temperature at about the
operating point by adjusting the T
the control loop.
fans can be run at 100% for maximum cooling.
temperature control slope.
LOW
HIGH
MIN
THERM
RANGE
T
. This is the temperature at which the fan turns on
LOW
. If temperature drops below the T
. If temperature exceeds the T
Figure 20. Dynamic T
. If temperature exceeds this critical limit, the
. This programs the PWM duty cycle versus
MIN
MIN
T
MIN
control mode programming.
CONTROL PROGRAMMING
OPERATING
POINT
MIN
control mode is a basic extension
T
HIGH
T
THERM
MIN
Control Loop
T
RANGE
MIN
HIGH
MIN
control loop. A
TEMPERATURE
limit, an error
parameter of
LOW
AN-613
limit, an