Step 2: Configuring The Mux - Analog Devices dBCool ADT7473 Manual

ADT7473
STEP 2: CONFIGURING TH
After the system hardware configuration is determined, the f
can be assigned to particular temperature channels. Not only
can fans be assigned to individual channels, but the behavio
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
tem erature channels. The mux is the bridge between p
temp erature measurement channels and the three PWM
outp uts.
Bits [7:5] (BHVR) of Register 0x5C, Register 0x5D, and
Re ster 0x5E (PWM configuration registers) control the gi
beha vior of the fans connecte
PWM3 outputs. The values selected for these bits determine
ho the mux connects a temperature measurement channel w
PWM output.
REMOTE 1 =
AMBIENT TEMP
LOCAL =
VRM TEMP
REMOTE 2 =
CPU TEMP
E MUX
d to the PWM1, PWM2, and
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 47. Assigning Temperature Channels to Fan Channels
Automatic Fan Control
Bits [7:5] (BHVR), Register 0x5C, Register 0x5D, Register 0
ans
000 = Remote 1 temperature controls PWMx
r of
001 = Local temperature contr
010 = Remote 2 temperature controls PWMx
101 = Fastest speed calculated by local and Rem
temperature controls PWMx
110 = Fastest speed calculated by all three temperature
channel controls PWMx
The fastest speed calculated options pertain to controlling one
PWM output based on multiple temperature channels. Th
thermal characteristics of the three temperature zones can be
set to drive a single fan. An example is the fan turning on when
to a
Remote 1 temperature exceeds 60°C, or if the local temperature
exceeds 45°C.
Other Mux Options
Bits [7:5] (BHVR), Register 0x5C, Register 0x5D, Register 0x5E.
011 = PWMx runs full speed
100 = PWMx disabled (default)
111 = manual mode
In normal mode, PWMx runs under software control. In
this mode, PWM duty cycle registers (Register 0x30 to
Register 0x32) are writable and control the PWM outputs.
MUX
PWM
MIN
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 1
MEASUREMENT
PWM
MIN
RAMP
CONTROL
MUX
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 2
MEASUREMENT
PWM
MIN
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 3
AND 4
MEASUREMENT
Rev. A | Page 36 of 76
Mux Options
ols PWMx
PWM
CONFIG
PWM
PWM1
GENERATOR
TACH1
PWM
CPU FAN SINK
CONFIG
PWM
PWM2
GENERATOR
TACH2
PWM
CONFIG
FRONT CHASSIS
PWM
PWM3
GENERATOR
TACH3
REAR CHASSIS
x5E.
ote 2
e