ADT7476 Analog Devices, Inc., ADT7476 Datasheet - Page 49

• Manufacturer Part Number: ADT7476
• Description: Dbcool Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

The T
operating temperature of the system. Because exceeding any
T
effects. Ultimately, this limit should be set up as a fail-safe and
should not be exceeded under normal system operating conditions.
Note that T
no matter how automatic fan control settings are configured.
This allows some flexibility because a T
ed based on its slope, while a hard limit (such as 70°C) can be
programmed as T
full speed) by setting T
THERM 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
THERM
THERM
limit runs all fans at 100%, it has very negative acoustic
THERM
limit should be considered the maximum worst-case
limits are nonmaskable and affect the fan speed
MAX
AMBIENT TEMP
REMOTE 2 =
REMOTE 1 =
(the temperature at which the fan reaches
VRM TEMP
CPU TEMP
THERM
LOCAL =
100%
0%
to that limit (for example, 70°C).
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
T
MIN
MIN
MIN
MIN
RANGE
T
RANGE
value can be select-
T
T
T
RANGE
RANGE
RANGE
Figure 64. How T
T
100%
100%
100%
THERM
0%
0%
0%
MUX
THERM
Rev. B | Page 49 of 72
Relates to Automatic Fan Control
PWM
PWM
PWM
MIN
MIN
MIN
example, setting hysteresis on the Remote 1 channel also sets
the hysteresis on Remote 1 THERM .
Hysteresis Registers
Register 0x6D, Remote 1 and Local Temperature Hysteresis
Register
Register 0x6E, Remote 2 Temperature Hysteresis Register
Because each hysteresis setting is four bits, hysteresis values are
programmable from 1°C to 15°C. It is not recommended that
hysteresis values ever be programmed 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
acoustic noise.
CONFIG
CONFIG
CONFIG
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
Bits [7:4], Remote 1 Temperature Hysteresis (4°C default).
Bits [3:0], Local Temperature Hysteresis (4°C default).
Bits [7:4], Remote 2 Temperature Hysteresis (4°C default).
PWM
PWM
PWM
GENERATOR
GENERATOR
GENERATOR
AND 4
PWM
PWM
PWM
MIN
, between normal speed and off, creating unsettling
ENHANCEMENT)
ENHANCEMENT)
ENHANCEMENT)
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
RAMP
RAMP
RAMP
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
FRONT CHASSIS
REAR CHASSIS
CPU FAN SINK
ADT7476