Step 9: Operating Points For Temperature Channels - Analog Devices dBCool ADT7473 Manual

STEP 9: OPERATING POINTS FOR TEMPERAT
CHANNELS
The operating point for each temperature channel is the optimal
temperature for that thermal zone. The hotter each zone is
allowed to be, the quieter the system, because the fans are not
required to run as fast. The ADT7473 in eases or decreas
speeds as necessary to maintain the operating point temp
tur , allowing for system-to-system variation and removing the e
need for worst-case design. If a sensible operating point value i
chos en, any T value can be selected in the system charac-
MIN
terization. If the T value is too low, the fans run sooner than
MIN
req ired, and the temperature is below the operating poin u
resp onse, the ADT7473 increases T
longer and to allow the temperature zone to get closer to the
operating point. Likewise, too high a T
operating point to be exceeded, and in turn, the ADT7473
reduces T to turn the fans on sooner to cool the system.
MIN
REMOTE 2 =
CPU TEMP
LOCAL =
VRM TEMP
REMOTE 1 =
AMBIENT TEMP
URE
cr es fan
era-
t. In
to keep the fans off
MIN
value causes the
MIN
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
THERMAL CALIBRATION
100%
MUX
0%
T T
MIN RANGE
THERMAL CALIBRATION
100%
0%
T T
MIN RANGE
Figure 64. Operating Point Value Dynamically Ad
Rev. A | Page 49 of 76
Programming Operating Point Registers
There are three operating point registers, one for each
temperature channel. These 8-bit registers allow the operating
point temperatures to be programmed with 1°C resolution.
Operating Point Registers
Register 0x33, Remote 1 Operating Point = 0xA4
(100°C default)
s
Register 0x34, Local Operating Point = 0xA4 (100°C d
Register 0x35, Remote 2 Operating Point = 0xA4
(100°C default)
PW M
MI N
OPERATING
RAMP
POINT CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 1
MEASUREMENT
PW M
MI N
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 2
MEASUREMENT
PW M
MI N
RAMP
CONTROL
(ACOUSTIC
ENHANCEMENT)
TACHOMETER 3
AND 4
MEASUREMENT
jus Automatic Fan Control Settings ts
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
ADT7473
efault)