ADT7463 Analog Devices, ADT7463 Datasheet - Page 12

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

AN-613
STEP 6: DETERMINING T
CHANNEL
T
on a temperature channel. Above this temperature, a
component such as the CPU or VRM may be operating
beyond its safe operating limit. When the temperature
measured exceeds T
duty cycle (full speed) to provide critical system cooling.
The fans remain running 100% until the temperature drops
below T
number programmed into hysteresis registers 0x6D and
0x6E. The default hysteresis value is 4°C.
The T
worst-case operating temperature of the system. Since
exceeding any T
very negative acoustic effects. Ultimately, this limit
should be set up as a failsafe, and one should ensure
that it is not exceeded under normal system operating
conditions.
THERM
THERM
is the absolute maximum temperature allowed
THERM
limit should be considered the maximum
AMBIENT TEMP
– hysteresis. The hysteresis value is the
REMOTE 2 =
REMOTE 1 =
VRM TEMP
CPU TEMP
THERM
100%
LOCAL =
0%
THERM
limit runs all fans at 100%, it has
THERM
, all fans are driven at 100% PWM
Figure 16. Understanding How T
T
MIN
T
T
T
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
MIN
MIN
MIN
FOR EACH TEMPERATURE
T
RANGE
T
T
T
RANGE
RANGE
RANGE
T
THERM
100%
100%
0%
100%
0%
0%
MUX
THERM
PWM
–12–
MIN
PWM
MIN
PWM
MIN
Relates to Automatic Fan Control
RAMP CONTROL
TACHOMETER 1
MEASUREMENT
ENHANCEMENT)
RAMP CONTROL
ENHANCEMENT)
RAMP CONTROL
ENHANCEMENT)
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
Note that the T
the fan speed no matter what automatic fan control set-
tings are configured. This allows some flexibility since a
T
“hard limit,” e.g., 70°C, can be programmed as T
temperature at which the fan reaches full speed) by set-
ting T
THERM REGISTERS
Reg. 0x6A Remote 1 THERM limit = 0x64 (100°C default)
Reg. 0x6B Local Temp THERM limit = 0x64 (100°C
default)
Reg. 0x6C Remote 2 THERM limit = 0x64 (100°C default)
HYSTERESIS REGISTERS
Reg. 0x6D Remote 1, Local Hysteresis Register
<7:4> = Remote 1 Temp Hysteresis (4°C default)
<3:0> = Local Temp Hysteresis (4°C default)
Reg. 0x6E Remote 2 Temp Hysteresis Register
<7:4> = Remote 2 Temp Hysteresis (4°C default)
Since each hysteresis setting is four bits, hysteresis values
are programmable from 1°C to 15°C. It is not recom-
mended that hysteresis values ever be programmed to
0°C, as this actually disables hysteresis. In effect, this
would cause the fans to cycle between normal speed and
100% speed, creating unsettling acoustic noise.
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
RANGE
AND 4
THERM
value can be selected based on its slope, while a
to 70°C.
GENERATOR
GENERATOR
GENERATOR
CONFIG
PWM
CONFIG
THERM
CONFIG
PWM
PWM
PWM
PWM
PWM
limits are nonmaskable and affect
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
CPU
FAN SINK
FRONT
CHASSIS
REAR
CHASSIS
MAX
REV. 0
(the