adt7476a Analog Devices, Inc., adt7476a Datasheet - Page 47

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

Note: T
matter how automatic fan control settings are configured. This
allows some flexibility, because a T
based on its slope, while a hard limit (such as 70°C), can be
programmed as T
full speed) by setting T
THERM Limit Registers
Register 0x6A, Remote 1 THERM Limit = 0x64 (100°C default)
Register 0x6B, Local THERM Limit = 0x64 (100°C default)
Register 0x6C, Remote 2 THERM Limit = 0x64 (100°C default)
THERM Hysteresis
THERM hysteresis on a particular channel is configured via the
hysteresis settings (Register 0x6D and Register 0x6E). For
example, setting hysteresis on the Remote 1 channel also sets
the hysteresis on Remote 1 THERM .
THERM
limits are nonmaskable and affect the fan speed no
AMBIENT TEMP
MAX
REMOTE 2 =
REMOTE 1 =
VRM TEMP
CPU TEMP
(the temperature at which the fan reaches
LOCAL =
100%
THERM
0%
to that limit (for example, 70°C).
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
T
MIN
MIN
MIN
MIN
RANGE
value can be selected
T
RANGE
T
T
T
RANGE
RANGE
RANGE
Figure 64. How T
T
100%
100%
100%
THERM
0%
0%
0%
MUX
THERM
Rev. 0 | Page 47 of 72
Relates to Automatic Fan Control
PWM
PWM
PWM
MIN
MIN
MIN
Hysteresis Registers
Register 0x6D, Remote 1, Local Temperature Hysteresis
[7:4], Remote 1 temperature hysteresis (4°C default).
[3:0], Local temperature hysteresis (4°C default).
Register 0x6E, Remote 2 Temperature Hysteresis
[7:4], Remote 2 temperature hysteresis (4°C default).
Because each hysteresis setting is four bits, hysteresis values
are programmable from 1°C to 15°C. It is not recommended to
program hysteresis values to 0°C, because this disables
hysteresis. In effect, this causes the fans to cycle (during a
THERM event) between normal speed and 100% speed, or,
while operating close to T
creating unsettling acoustic noise.
CONFIG
CONFIG
CONFIG
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
GENERATOR
GENERATOR
GENERATOR
AND 4
PWM
PWM
PWM
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
RAMP
RAMP
RAMP
MIN
, between normal speed and off,
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
ADT7476A