ADT7468 Analog Devices, Inc., ADT7468 Datasheet - Page 45

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

STEP 3: T
CALIBRATION CHANNELS
T
automatic fan control. The speed at which the fan runs at T
programmed later. The T
channel specific, for example, 25°C for ambient channel, 30°C
for VRM temperature, and 40°C for processor temperature.
T
can be programmed in 1°C increments. There is a T
associated with each temperature measurement channel:
Remote 1 local, and Remote 2 temperature. Once the T
is exceeded, the fan turns on and runs at the minimum PWM
duty cycle. The fan turns off once the temperature has dropped
below T
To overcome fan inertia, the fan is spun up until two valid
TACH rising edges are counted. See the Fan Start-Up Timeout
section for more details. In some cases, primarily for psycho-
acoustic reasons, it is desirable that the fan never switch off
below T
(Reg. 0x62), when set, keep the fans running at the PWM
minimum duty cycle, if the temperature should fall below T
MIN
MIN
is the temperature at which the fans start to turn on under
is an 8-bit value, either twos complement or Offset 64, that
MIN
MIN
. Bits <7:5> of Enhanced Acoustics Register 1
MIN
– T
HYST
SETTINGS FOR THERMAL
.
AMBIENT TEMP
REMOTE 2 =
REMOTE 1 =
MIN
VRM TEMP
CPU TEMP
LOCAL =
100%
values chosen are temperature
0%
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
T
MIN
MIN
MIN
MIN
T
T
T
RANGE
RANGE
RANGE
Figure 58. Understanding the T
100%
100%
100%
MIN
0%
0%
0%
MIN
register
value
MUX
MIN
MIN
Rev. A | Page 45 of 84
is
.
PWM
PWM
PWM
MIN
MIN
MIN
T
Reg. 0x67, Remote 1 temperature T
Reg. 0x68, Local temperature T
Reg. 0x69, Remote 2 temperature T
Enhance Acoustics Register 1 (Reg. 0x62)
Bit 7 (MIN3) = 0, PWM3 is off (0% PWM duty cycle) when
temperature is below T
Bit 7 (MIN3) = 1, PWM3 runs at PWM3 minimum duty cycle
below T
Bit 6 (MIN2) = 0, PWM2 is off (0% PWM duty cycle) when
temperature is below T
Bit 6 (MIN2) = 1, PWM2 runs at PWM2 minimum duty cycle
below T
Bit 5 (MIN1) = 0, PWM1 is off (0% PWM duty cycle) when
temperature is below T
Bit 5 (MIN1) = 1, PWM1 runs at PWM1 minimum duty cycle
below T
MIN
MIN
ENHANCEMENT)
ENHANCEMENT)
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
ENHANCEMENT)
TACHOMETER 3
MEASUREMENT
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
Parameter
Registers
RAMP
RAMP
RAMP
AND 4
MIN
MIN
MIN
– T
– T
– T
HYST
HYST
HYST
GENERATOR
GENERATOR
GENERATOR
CONFIG
CONFIG
CONFIG
.
.
.
PWM
PWM
PWM
PWM
PWM
PWM
MIN
MIN
MIN
– T
– T
– T
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
HYST
HYST
HYST
MIN
.
.
.
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
= 0x9A (90°C)
MIN
MIN
= 0x9A (90°C)
= 0x9A (90°C)
ADT7468