adt7476a Analog Devices, Inc., adt7476a Datasheet - Page 40

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

ADT7476A
STEP 2—CONFIGURING THE MUX
After the system hardware configuration is determined, the fans
can be assigned to particular temperature channels. Not only
can fans be assigned to individual channels, but the behavior
of the fans is also configurable. For example, fans can be run under
automatic fan control, manually (under software control), or at
the fastest speed calculated by multiple temperature channels. The
mux is the bridge between temperature measurement channels
and the three PWM outputs.
Bits [7:5] (BHVR) of Register 0x5C, Register 0x5D, and
Register 0x5E (PWM configuration registers) control the behavior
of the fans connected to the PWM1, PWM2, and PWM3 outputs.
The values selected for these bits determine how the mux connects
a temperature measurement channel to a PWM output.
Automatic Fan Control Mux Options
[7:5] (BHVR), Register 0x5C, Register 0x5D, Register 0x5E.
000 = Remote 1 temperature controls PWMx
001 = Local temperature controls PWMx
010 = Remote 2 temperature controls PWMx
AMBIENT TEMP
REMOTE 1 =
REMOTE 2 =
VRM TEMP
CPU TEMP
LOCAL =
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
T
T
T
MIN
MIN
MIN
T
T
T
Figure 51. Assigning Temperature Channels to Fan Channels
RANGE
RANGE
RANGE
100%
100%
100%
0%
0%
0%
MUX
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MUX
PWM
PWM
PWM
MIN
MIN
MIN
CONFIG
CONFIG
CONFIG
The fastest speed calculated options pertain to controlling
one PWM output based on multiple temperature channels.
The thermal characteristics of the three temperature zones
can be set to drive a single fan. An example would be the fan
turning on when Remote 1 temperature exceeds 60°C or if
the local temperature exceeds 45°C.
Other Mux Options
[7:5] (BHVR), Register 0x5C, Register 0x5D, Register 0x5E.
TACHOMETER 1
MEASUREMENT
TACHOMETER 2
MEASUREMENT
TACHOMETER 3
MEASUREMENT
PWM
PWM
PWM
GENERATOR
GENERATOR
GENERATOR
101 = Fastest speed calculated by local and Remote 2
temperature controls PWMx
110 = Fastest speed calculated by all three temperature
channels controls PWMx
011 = PWMx runs full speed
100 = PWMx disabled (default)
111 = Manual mode. PWMx is running under software
control. In this mode, PWM current duty cycle registers
(0x30 to 0x32) are writable and control the PWM outputs.
AND 4
PWM
PWM
PWM
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