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Mux Configuration Example
This is an example of how to configure the mux in a
system using the ADT7476A to control three fans. The CPU
fan sink is controlled by PWM1, the front chassis fan is
controlled by PWM2, and the rear chassis fan is controlled
by PWM3. The mux is configured for the following fan
control behavior:
•
PWM1 (CPU fan sink) is controlled by the fastest speed
calculated by the local (VRM temperature) and
Remote 2 (processor) temperature. In this case, the
CPU fan sink is also being used to cool the VRM.
•
PWM2 (front chassis fan) is controlled by the Remote 1
temperature (ambient).
•
PWM3 (rear chassis fan) is controlled by the Remote 1
temperature (ambient).
REMOTE2 =
CPU TEMP
LOCAL =
VRM TEMP
REMOTE1 =
AMBIENT TEMP
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THERMAL CALIBRATION
100%
0%
T
T
MIN
RANGE
MUX
THERMAL CALIBRATION
100%
0%
T
T
MIN
RANGE
THERMAL CALIBRATION
100%
0%
T
T
MIN
RANGE
Figure 52. Mux Configuration Example
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ADT7476A
Example Mux Settings
[7:5] (BHVR), PWM1 Configuration Register (0x5C).
101 = Fastest speed calculated by local and Remote 2
temperature controls PWM1
[7:5] (BHVR), PWM2 Configuration Register (0x5D).
000 = Remote 1 temperature controls PWM2
[7:5] (BHVR), PWM3 Configuration Register (0x5E).
000 = Remote 1 temperature controls PWM3
These settings configure the mux, as shown in Figure 52.
PWM
MIN
PWM
CONFIG
PWM
S
GENERATOR
ENHANCEMENT)
TACHOMETER1
MEASUREMENT
PWM
MIN
PWM
CONFIG
PWM
S
GENERATOR
ENHANCEMENT)
TACHOMETER2
MEASUREMENT
PWM
MIN
PWM
CONFIG
PWM
S
GENERATOR
ENHANCEMENT)
TACHOMETER3
AND 4
MEASUREMENT
39
RAMP
CONTROL
PWM1
(ACOUSTIC
TACH1 CPU FAN SINK
RAMP
CONTROL
PWM2
(ACOUSTIC
TACH2
FRONT CHASSIS
RAMP
CONTROL
PWM3
(ACOUSTIC
TACH3
REAR CHASSIS
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