ADT7468 Analog Devices, Inc., ADT7468 Datasheet - Page 51

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

STEP 8: T
T
temperature measured has dropped back below T
fan turns off. The premise for temperature hysteresis (T
that, without it, the fan would merely chatter or cycle on and off
regularly whenever temperature is hovering at about the T
setting.
The T
for the system to cool down or heat up as the fan is turning on
and off. Values of hysteresis are programmable in the range 1°C
to 15°C. Larger values of T
on and off. The T
The T
for fan on/off, but the same setting is used for the T
hysteresis value, described in Step 6. Therefore, programming
Registers 0x6D and 0x6E sets the hysteresis for both fan on/off
and the THERM function.
HYST
is the amount of extra cooling a fan provides after the
HYST
HYST
value chosen determines the amount of time needed
setting applies not only to the temperature hysteresis
HYST
FOR TEMPERATURE CHANNELS
HYST
default value is set at 4°C.
AMBIENT TEMP
HYST
REMOTE 2 =
REMOTE 1 =
CPU TEMP
VRM TEMP
LOCAL =
100%
prevent the fans from chattering
0%
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
T
MIN
MIN
MIN
MIN
Figure 68. How T
T
RANGE
T
T
T
RANGE
RANGE
RANGE
MIN
THERM
T
100%
100%
100%
THERM
before the
0%
0%
0%
HYST
MIN
MUX
) is
THERM
Rev. A | Page 51 of 84
Relates to Automatic Fan Control
PWM
PWM
PWM
MIN
MIN
MIN
Hysteresis Registers
Reg. 0x6D, Remote 1, local hysteresis register
<7:4>, Remote 1 temperature hysteresis (4°C default).
<3:0>, local temperature hysteresis (4°C default).
Reg. 0x6E, Remote 2 temperature hysteresis register
<7:4>, Remote 2 temperature hysteresis (4°C default).
In some applications, it is required that fans not turn off below
T
Acoustics Register 1 (Reg. 0x62) allow the fans to be turned off
or to be kept spinning below T
T
below T
MIN
HYST
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
, but remain running at PWM
RAMP
RAMP
RAMP
AND 4
value has no effect on the fan when the temperature drops
MIN
.
GENERATOR
GENERATOR
GENERATOR
CONFIG
CONFIG
CONFIG
PWM
PWM
PWM
PWM
PWM
PWM
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
MIN
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
. If the fans are always on, the
MIN
. Bits <7:5> of Enhanced
ADT7468