adt7476a Analog Devices, Inc., adt7476a Datasheet - Page 48

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

ADT7476A
STEP 8—T
T
temperature measured has dropped back below T
the fan turns off. The premise for temperature hysteresis (T
is that without it, the fan would merely chatter, or cycle on
and off regularly, whenever the temperature hovers around
the T
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
HYST
MIN
is the amount of extra cooling a fan provides after the
HYST
setting.
value chosen determines the amount of time needed
HYST
AMBIENT TEMP
REMOTE 2 =
REMOTE 1 =
HYST
FOR TEMPERATURE CHANNELS
VRM TEMP
CPU TEMP
LOCAL =
100%
default value is set at 4°C.
0%
HYST
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
prevent the fans from chattering
T
T
T
T
MIN
MIN
MIN
MIN
Figure 65. The T
T
RANGE
T
T
T
RANGE
RANGE
RANGE
T
100%
100%
100%
THERM
HYST
0%
0%
0%
MIN
Value Applies to Fan On/Off Hysteresis and THERM Hysteresis
before
MUX
HYST
Rev. 0 | Page 48 of 72
)
PWM
PWM
PWM
MIN
MIN
MIN
CONFIG
CONFIG
CONFIG
The T
for fan on/off, but the same setting is used for the T
value, described in Step 6—T
Therefore, programming Register 0x6D and Register 0x6E sets
the hysteresis for both fan on/off and the THERM function.
In some applications, it is required that fans not turn off below T
but remain running at PWM
Register 1 (0x62) allow the fans to be turned off or to be kept
spinning below T
has no effect on the fan when the temperature drops below T
THERM Hysteresis
Any hysteresis programmed via Register 0x6D and Register 0x6E
also applies hysteresis on the appropriate THERM channel.
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
GENERATOR
GENERATOR
GENERATOR
AND 4
PWM
PWM
PWM
HYST
setting applies not only to the temperature hysteresis
MIN
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
. If the fans are always on, the T
RAMP
RAMP
RAMP
MIN
RANGE
. Bits [7:5] of Enhance Acoustics
for Temperature Channels.
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
THERM
HYST
hysteresis
value
MIN
MIN
.