Analog Devices dBCool ADT7473 Manual page 37

Mux Configuration Example
This is an example of how to conf
using the ADT7473 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 behaviors:
•
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 sin
also used to cool the VRM.
•
PWM2 (front chassis fan) is controlled by the Remote 1
temperature (ambient).
•
PWM3 (r ear chassis fan) is controlled by the Remote 1
temperature (ambient).
REMOTE 2 =
CPU TEMP
LOCAL =
VRM TEMP
REMOTE 1 =
AMBIENT TEMP
igure the mux in a system
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
Figure 48. Mux Configuration Example
Example Mux Settings
Bits [7:5] (BHVR), PWM1 Configuration Register (0x5C)
101 = Fastest speed calculated by local and Remote
temperature controls PWM1
Bits [7:5] (BHVR), PWM2 Configuration
000 = Remote 1 temperature controls PWM2
Bits [7:5] (BHVR), PWM3 Configura
k is
000 = Remote 1 temperature controls PWM3
These settings configure the mux, as shown in Figure 48.
PW M
MIN
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER
MUX
MEASUREME
PWM
MIN
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 2
MEASUREMENT
PWM
MIN
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 3
AND 4
MEASUREMENT
Rev. A | Page 37 of 76
Register (0x5D)
tion Register (0x5E)
PWM
CONFIG
PWM
PWM1
GENERATOR
1
TACH1
NT
PWM
CPU FAN SINK
CONFIG
PWM
PWM2
GENERATOR
TACH2
PWM
CONFIG
FRONT CHASSIS
PWM
PWM3
GENERATOR
TACH3
REAR CHASSIS
ADT7473
2