adt7476a Analog Devices, Inc., adt7476a Datasheet - Page 42

• Manufacturer Part Number: adt7476a
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

ADT7476A
STEP 3—T
CALIBRATION CHANNELS
T
automatic fan control. The speed at which the fan runs at T
is 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
which can be programmed in 1°C increments. A T
is associated with each temperature measurement channel:
Remote 1, local, and Remote 2 temperature. Once the T
value 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 Startup Timeout section
for more details. In some cases, primarily for psycho-acoustic
reasons, it is desirable that the fan never switch off below T
Setting Bits [7:5] of Enhance Acoustics Register 1 (0x62) keeps
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,
MIN
SETTINGS FOR THERMAL
MIN
AMBIENT TEMP
REMOTE 2 =
REMOTE 1 =
− T
VRM TEMP
CPU TEMP
LOCAL =
100%
HYST
0%
MIN
.
values chosen are temperature
MIN
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
.
T
T
T
MIN
MIN
MIN
MIN
T
T
T
RANGE
RANGE
RANGE
100%
100%
100%
Figure 53. Understanding the T
MIN
0%
0%
0%
register
MIN
MIN
MUX
MIN
.
Rev. 0 | Page 42 of 72
PWM
PWM
PWM
MIN
MIN
MIN
CONFIG
CONFIG
CONFIG
T
Register 0x67, Remote 1 Temperature T
Register 0x68, Local Temperature T
Register 0x69, Remote 2 Temperature T
Enhance Acoustics Register 1 (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
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
MIN
GENERATOR
GENERATOR
GENERATOR
MIN
AND 4
Registers
PWM
PWM
PWM
Parameter
MIN
MIN
MIN
– T
– T
– T
HYST
HYST
HYST
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
.
.
.
RAMP
RAMP
RAMP
MIN
MIN
MIN
– T
– T
– T
HYST
HYST
HYST
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
.
.
.
MIN
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
= 0x5A (90°C)
MIN
MIN
= 0x5A (90°C)
= 0x5A (90°C)