ADT7476 Analog Devices, Inc., ADT7476 Datasheet - Page 43

• Manufacturer Part Number: ADT7476
• 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
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
can be programmed in 1°C increments. A T
iated with each temperature measurement channel: Remote 1
local and Remote 2 temperature. Once the T
the fan turns on and runs at the minimum PWM duty cycle.
The fan turns off once the temperature has dropped below T
− 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
When set, Bits [7:5] of Enhanced Acoustics Register 1 (0x62)
keep the fans running at the PWM minimum duty cycle if the
temperature should fall below T
MIN
MIN
HYST
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
AMBIENT TEMP
SETTINGS FOR THERMAL
REMOTE 2 =
REMOTE 1 =
VRM TEMP
CPU TEMP
LOCAL =
MIN
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
values chosen are temperature
MIN
T
T
T
MIN
MIN
MIN
.
MIN
T
T
T
MIN
RANGE
RANGE
RANGE
value is exceeded,
register is assoc-
100%
100%
100%
0%
0%
0%
Figure 52. MUX Configuration Example
MIN
MUX
MIN
.
MIN
Rev. B | Page 43 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
Enhanced 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
MIN
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
GENERATOR
GENERATOR
GENERATOR
Registers
AND 4
PWM
PWM
PWM
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
.
.
.
MIN
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
= 0x5A (90°C)
MIN
MIN
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
= 0x5A (90°C)
= 0x5A (90°C)
ADT7476