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PDF ADM1031 Data sheet ( Hoja de datos )
| Número de pieza | ADM1031 | |
| Descripción | Intelligent Temperature Monitor and Dual PWM Fan Controller | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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a
Intelligent Temperature
Monitor and Dual PWM Fan Controller
ADM1031
FEATURES
Optimized for Pentium® III: Allows Reduced Guardbanding
Software and Automatic Fan Speed Control
Automatic Fan Speed Control Allows Control Indepen-
dent of CPU Intervention after Initial Setup
Control Loop Minimizes Acoustic Noise and Battery
Consumption
Remote Temperature Measurement Accurate to 1؇C
Using Remote Diode (Two Channels)
0.125؇C Resolution on External Temperature Channels
Local Temperature Sensor with 0.25؇C Resolution
Pulsewidth Modulation Fan Control (PWM) for Two Fans
Programmable PWM Frequency
Programmable PWM Duty Cycle
Tach Fan Speed Measurement (Two Channels)
Analog Input To Measure Fan Speed of 2-Wire Fans
(Using Sense Resistor)
2-Wire System Management Bus (SMBus) with ARA
Support
Overtemperature THERM Output Pin for CPU Throttling
Programmable INT Output Pin
Configurable Offsets for Temperature Channels
3 V to 5.5 V Supply Range
Shutdown Mode to Minimize Power Consumption
Limit Comparison of All Monitored Values
APPLICATIONS
Notebook PCs, Network Servers and Personal Computers
Telecommunications Equipment
PRODUCT DESCRIPTION
The ADM1031 is an ACPI-compliant three-channel digital
thermometer and under/over temperature alarm, for use in
personal computers and thermal management systems. Opti-
mized for the Pentium III, the higher 1°C accuracy offered
allows systems designers to safely reduce temperature guard-
banding and increase system performance. Two Pulsewidth
Modulated (PWM) Fan Control outputs control the speed of
two cooling fans by varying output duty cycle. Duty cycle values
between 33%–100% allow smooth control of the fans. The speed
of each fan can be monitored via TACH inputs. The TACH
inputs may be reprogrammed as analog inputs, allowing fan
speeds for 2-wire fans to be measured via sense resistors. The
device will also detect a stalled fan. A dedicated Fan Speed
Control Loop provides control even without the intervention of
CPU software. It also ensures that if the CPU or system locks up,
each fan can still be controlled based on temperature measure-
ments, and the fan speed adjusted to correct any changes in
system temperature. Fan speed may also be controlled using
existing ACPI software. Two inputs (four pins) are dedicated to
remote temperature-sensing diodes with an accuracy of ± 1°C,
and an on-chip temperature sensor allows ambient temperature
to be monitored. The device has a programmable INT output
to indicate error conditions. There is a dedicated FAN_FAULT
output to signal fan failure. The THERM pin is a fail-safe output
for overtemperature conditions that can be used to throttle a
CPU clock.
FUNCTIONAL BLOCK DIAGRAM
VCC
PWM_OUT1
PWM_OUT2
TACH2 /AIN2
TACH1 /AIN1
D1+
D1–
D2+
D2–
*Patents pending.
Pentium is a registered
trademark of Intel Corporation.
REV. 0
ADM1031
PWM
CONTROLLERS
TACH SIGNAL
CONDITIONING
SLAVE
ADDRESS
REGISTER
FAN FILTER
REGISTER
FAN
CHARACTERISTICS
REGISTERS
FAN SPEED
CONFIG
REGISTER
FAN SPEED
COUNTER
BANDGAP
TEMPERATURE
SENSOR
ANALOG
MULTIPLEXER
ADC
2.5V
BANDGAP
REFERENCE
GND
SERIAL BUS
INTERFACE
ADDRESS
POINTER
REGISTER
INTERRUPT
STATUS
REGISTERS
LIMIT
COMPARATOR
VALUE AND LIMIT
REGISTERS
OFFSET
REGISTERS
CONFIGURATION
REGISTERS
ADD
SDA
SCL
INT (SMBALERT)
THERM
FAN_FAULT
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2001
1 page  
Typical Performance Characteristics–ADM1031
15
10
5
DXP TO GND
0
DXP TO VCC (3.3V)
–5
–10
–15
–20
1
3.3 10
30
LEAKAGE RESISTANCE – M⍀
100
TPC 1. Temperature Error vs. PCB Track Resistance
110
100
90
80
70
60
50
40
30
20
10
0
0 10 20 30 40 50 60 70 80 90 100 110
PIII TEMPERATURE – ؇C
TPC 4. Pentium III Temperature Measurement vs.
ADM1031 Reading
17
15 VIN = 100mV p-p
13
11
9
7
5
3
1
–1
0
VIN = 200mV p-p
500k
2M 4M 6M 10M 100M 400M
FREQUENCY – Hz
TPC 2. Temperature Error vs. Power Supply Noise
Frequency
1
0
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
–11
–12
–13
–14
–15
–16
1
2.2 3.3 4.7 10 22
DXP – DXN CAPACITANCE – nF
47
TPC 5. Temperature Error vs. Capacitance between
D+ and D–
7
6
5
4
3
VIN = 40mV p-p
2
1
0
–1
0
VIN = 20mV p-p
100k 1M 100M 200M 300M 400M 500M
FREQUENCY – Hz
TPC 3. Temperature Error vs. Common-Mode Noise
Frequency
110
100
90
80
70
60 VCC = 5V
50
40
30
20 VCC = 3.3V
10
0
0 1 5 10 25 50 75 100 250 500 750 1000
SCLK FREQUENCY – kHz
TPC 6. Standby Current vs. Clock Frequency
REV. 0
–5–
5 Page 
ADM1031
asserted low. The behavior of the high limit and THERM limit
is as follows:
1. Whenever the temperature measured exceeds the high tem-
perature limit, the INT pin is asserted low.
2. If the temperature exceeds the THERM limit, the THERM
output asserts low. This can be used to throttle the CPU
clock. If the THERM-to-Fan Enable bit (Bit 7 of THERM
behavior/revision register) is cleared to 0, the fans will not
run full-speed. The THERM limit may be programmed at
a lower temperature than the high temperature limit. This
allows the system to run in silent mode, where the CPU can
be throttled while the cooling fan is off. If the temperature
continues to increase, and exceeds the high temperature limit,
an INT is generated. Software may then decide whether the
fan should run to cool the CPU. This allows the system to
run in SILENT MODE.
3. If the THERM-to-Fan Enable bit is set to 1, the fan will run
full-speed whenever THERM is asserted low. In this case,
both throttling and active cooling take place. If the high
temperature limit is programmed to a lower value than the
THERM limit, exceeding the high temperature limit will
assert INT low. Software could change the speed of the fan
depending on temperature readings. If the temperature con-
tinues to increase and exceeds the THERM limit, THERM
asserts low to throttle the CPU and the fan runs full-speed.
This allows the system to run in PERFORMANCE MODE,
where active cooling takes place and the CPU is only throttled
at high temperature.
Using the high temperature limit and the THERM limit in this
way allows the user to gain maximum performance from the system
by only slowing it down, should it be at a critical temperature.
Although the ADM1031 does not have a dedicated Interrupt
Mask Register, clearing the appropriate enable bits in Configu-
ration Register 2 will clear the appropriate interrupts and mask
out future interrupts on that channel. Disabling interrupt bits
will prevent out-of-limit conditions from generating an interrupt
or setting a bit in the Status Registers.
USING THERM AS AN INPUT
The THERM pin is an open-drain input/output pin. When
used as an output, it signals overtemperature conditions. When
asserted low as an output, the fan will be driven full-speed if the
THERM-to-Fan Enable bit is set to 1 (Bit 7 of Register 0x3F).
When THERM is pulled low as an input, the THERM bit (Bit 7)
of Status Register 2 is set to 1, and the fans are driven full-speed.
Note that the THERM-to-Fan Enable bit has no effect when-
ever THERM is used as an input. If THERM is pulled low as
an input, and the THERM-to-Fan Enable bit = 0, the fans will
still be driven full-speed. The THERM-to-Fan Enable bit only
affects the behavior of THERM when used as an output.
STATUS REGISTERS
All out-of-limit conditions are flagged by status bits in Status
Registers 1 and 2 (0x02, 0x03). Bits 0 and 1 (Alarm Speed, Fan
Fault) of Status Register 1, once set, may be cleared by reading
Status Register 1. Once the Alarm Speed bit is cleared, this bit
will not be reasserted on the next monitoring cycle even if the
condition still persists. This bit may be reasserted only if the
fan is no longer at Alarm Speed. Bit 1 (Fan Fault) is set when-
ever a fan tach failure is detected.
Once cleared, it will reassert on subsequent fan tach failures.
Bits 2 and 3 of Status Registers 1, 2 are the Remote 1, 2 Tem-
perature High and Low status bits. Exceeding the high or low
temperature limits for the external channel sets these status bits.
Reading the status register clears these bits. However, these bits
will be reasserted if the out-of limit condition still exists on the next
monitoring cycle. Bits 6 and 7 are the Local Temperature High
and Low status bits. These behave exactly the same as the Remote
Temperature High and Low status bits. Bit 4 of Status Regis-
ter 1 indicates that the Remote Temperature THERM limit
has been exceeded. This bit gets cleared on a read of Status
Register 1 (see Figure 5). Bit 5 indicates a Remote Diode Error.
This bit will be a 1 if a short or open is detected on the Remote
Temperature channel on power-up. If this bit is set to 1 on
power-up, it cannot be cleared. Bit 6 of Status Register 2 (0x03)
indicates that the Local THERM limit has been exceeded. This bit
is cleared on a read of Status Register 2. Bit 7 indicates that
THERM has been pulled low as an input. This bit can also
be cleared on a read of Status Register 2.
THERM LIMIT
TEMP
5؇
THERM
INT REARMED
INT
STATUS REG. READ
Figure 5. Operation of THERM and INT Signals
Figure 5 shows the interaction between INT and THERM.
Once a critical temperature THERM limit is exceeded, both
INT and THERM assert low. Reading the Status Registers
clears the interrupt and the INT pin goes high. However, the
THERM pin remains asserted until the measured temperature
falls 5°C below the exceeded THERM limit. This feature can be
used to CPU throttle or drive a fan full speed for maximum
cooling. Note, that the INT pin for that interrupt source is not
rearmed until the temperature has fallen below the THERM
limit –5°C. This prevents unnecessary interrupts from tying up
valuable CPU resources.
MODES OF OPERATION
The ADM1031 has four different modes of operation. These
modes determine the behavior of the system.
1. Automatic Fan Speed Control Mode.
2. Filtered Automatic Fan Speed Control Mode.
3. PWM Duty Cycle Select Mode (directly sets fan speed under
software control).
4. RPM Feedback Mode.
REV. 0
–11–
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet ADM1031.PDF ] | |
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