adm1027 Analog Devices, Inc., adm1027 Datasheet - Page 30

• Manufacturer Part Number: adm1027
• Description: Dbcool? Remote Thermal Controller And Voltage Monitor
• Manufacturer: Analog Devices, Inc.

ADM1027
Step 3
Determine T
T
under automatic fan control. The speed at which the fan runs
at T
temperature channel specific, e.g., 25∞C for ambient channel,
30∞C for VRM temperature, and 40∞C for processor temperature.
T
grammed in 1∞C increments. There is a T
with each temperature measurement channel, Remote 1, Local
and Remote 2 Temp. Once the T
turns on and runs at minimum PWM duty cycle. The fan will
turn off once temperature has dropped below T
(detailed later).
To overcome fan inertia, the fan is spun up until two valid TACH
rising edges are counted. See the Fan Start-Up Timeout section
for more details. In some cases, primarily for psycho-acoustic
reasons, it is desirable that the fan never switches off below T
Bits <7:5> of Enhance Acoustics Register 1 (Reg. 0x62), when
set, keep the fans running at PWM minimum duty cycle should
the temperature be below T
MIN
MIN
MIN
is the temperature at which the fans will start to turn on
is an 8-bit twos complement value that can be pro-
is programmed later. The T
MIN
AMBIENT TEMP
REMOTE 2 =
REMOTE 1 =
Setting for Each Thermal Channel
VRM TEMP
CPU TEMP
LOCAL =
100%
0%
MIN
T
T
T
MIN
MIN
MIN
.
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
MIN
T
MIN
MIN
value is exceeded, the fan
values chosen will be
MIN
T
T
T
RANGE
RANGE
RANGE
Figure 29. Understanding T
register associated
100%
MIN
100%
0%
100%
0%
0%
– T
HYST
MUX
MIN
.
–30–
PWM
PWM
PWM
T
Reg. 0x67 Remote 1 Temperature T
Reg. 0x68 Local Temperature T
Reg. 0x69 Remote 2 Temperature T
Enhance Acoustics Reg 1 (Reg. 0x62)
Bit 7 (MIN3) = 0, PWM3 is OFF (0% PWM duty cycle) when
temperature is below T
Bit 7 (MIN3) = 1, PWM3 runs at PWM3 minimum duty cycle
below T
Bit 6 (MIN2) = 0, PWM2 is OFF (0% PWM duty cycle) when
temperature is below T
Bit 6 (MIN2) = 1, PWM2 runs at PWM2 minimum duty cycle
below T
Bit 5 (MIN1) = 0, PWM1 is OFF (0% PWM duty cycle) when
temperature is below T
Bit 5 (MIN1) = 1, PWM1 runs at PWM1 minimum duty cycle
below T
MIN
MIN
MIN
MIN
MIN
Registers
TACHOMETERS 3
MEASUREMENT
ENHANCEMENT
TACHOMETER 1
MEASUREMENT
ENHANCEMENT
TACHOMETER 2
MEASUREMENT
ENHANCEMENT
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
MIN
MIN
MIN
AND 4
Parameter
RAMP
RAMP
RAMP
– T
– T
– T
HYST
HYST
HYST
GENERATOR
GENERATOR
GENERATOR
.
.
.
CONFIG
CONFIG
CONFIG
PWM
PWM
PWM
PWM
PWM
PWM
MIN
MIN
MIN
– T
– T
– T
HYST
HYST
HYST
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
MIN
.
.
.
= 0x5A (90∞C default)
MIN
MIN
= 0x5A (90∞C default)
= 0x5A (90∞C default)
CPU
FANSINK
FRONT
CHASSIS
REAR
CHASSIS
REV. A