ADM1027ARQ-REEL ON Semiconductor, ADM1027ARQ-REEL Datasheet - Page 34

• Manufacturer Part Number: ADM1027ARQ-REEL
• Description: IC REMOTE THERMAL CTRLR 24-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADM1027ARQ-REEL

• Rohs Status: RoHS non-compliant
• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 105°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: 0°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 24-QSOP

ADM1027
Step 6
Determine T
T
temperature channel. Above this temperature, a component such
as the CPU or VRM may be operating beyond its safe operating
limit. When the measured temperature exceeds T
are driven at 100% PWM duty cycle (full speed) to provide
critical system cooling. The fans remain running at 100% until
the temperature drops below T
value is 4rC.
The T
case operating temperature of the system. Since exceeding any
T
effects. Ultimately, this limit should be set up as a fail-safe, and
the user should ensure that it is not exceeded under normal
system operating conditions.
THERM
THERM
THERM
is the absolute maximum temperature allowed on a
limit runs all fans at 100%, it has very negative acoustic
THERM
limit should be considered the maximum worst-
AMBIENT TEMP
REMOTE 2 =
REMOTE 1 =
VRM TEMP
CPU TEMP
100%
LOCAL =
for Each Temperature Channel
0%
Figure 35. Understanding How T
T
THERM
MIN
T
T
T
MIN
MIN
MIN
THERMAL CALIBRATION
THERMAL CALIBRATION
THERMAL CALIBRATION
– hysteresis. The hysteresis
T
RANGE
T
T
T
RANGE
RANGE
RANGE
T
THERM
100%
100%
0%
100%
0%
0%
THERM
Rev. 3 | Page 34 of 56 | www.onsemi.com
, all fans
MUX
THERM
–34–
PWM
PWM
PWM
Note that the T
speed no matter what automatic fan control settings are config-
ured. This allows some flexibility since a T
selected based on its slope, while a hard limit, e.g., 70rC, can be
programmed as T
full speed) by setting T
THERM hysteresis is 4rC.
THERM Registers
Reg. 0x6A Remote 1 THERM Limit = 0x64 (100rC default)
Reg. 0x6B Local Temperature THERM Limit = 0x64
(100rC default)
Reg. 0x6C Remote 2 THERM Limit = 0x64 (100rC default)
MIN
MIN
MIN
Relates to Automatic Fan Control
TACHOMETERS 3
MEASUREMENT
ENHANCEMENT)
TACHOMETER 1
ENHANCEMENT)
TACHOMETER 2
ENHANCEMENT)
MEASUREMENT
MEASUREMENT
(ACOUSTIC
(ACOUSTIC
(ACOUSTIC
CONTROL
CONTROL
CONTROL
AND 4
RAMP
RAMP
RAMP
THERM
MAX
GENERATOR
GENERATOR
GENERATOR
CONFIG
CONFIG
CONFIG
PWM
PWM
PWM
PWM
PWM
PWM
(the temperature at which the fan reaches
limits are nonmaskable and affect the fan
THERM
to 70rC.
PWM1
TACH1
PWM2
TACH2
PWM3
TACH3
RANGE
value can be
CPU
FANSINK
FRONT
CHASSIS
REAR
CHASSIS
REV. A