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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 | ON Semiconductor | |
| Logotipo |  |
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ADM1031
Intelligent Temperature
Monitor and Dual PWM Fan
Controller
The ADM1031 is an ACPI-compliant, three-channel digital
thermometer and under/overtemperature alarm for use in personal
computers and thermal management systems. Optimized for the
PentiumIII, the part offers a 1C higher accuracy, which allows
system designers to safely reduce temperature guard-banding and
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increase system performance.
Two PWM fan control outputs control the speed of two cooling fans
by varying output duty cycle. Duty cycle values between 33% and
100% allow smooth control of the fans. The speed of each fan can be
QSOP−16
CASE 492
monitored via TACH inputs, which can be reprogrammed as analog
inputs to allow speeds for 2-wire fans to be measured via sense
PIN ASSIGNMENT
resistors. The device also detects a stalled fan. A dedicated fan speed
control loop provides control without the intervention of CPU
PWM_OUT1 1
16 SCL
software. It also ensures that if the CPU or system locks up, each fan
TACH1/AIN1 2
15 SDA
can still be controlled based on temperature measurements, and the fan
PWM_OUT2 3
14 INT (SMBALERT)
speed is adjusted to correct any changes in system temperature. Fan
speed can also be controlled using existing ACPI software.
TACH2/AIN2 4
GND 5
ADM1031
13 ADD
12 D2+
Two inputs (4 pins) are dedicated to remote temperature-sensing
VCC 6
11 D2−
diodes with an accuracy of 1C, and an on-chip temperature sensor
allows ambient temperature to be monitored. The device has a
THERM 7
FAN_FAULT 8
10 D1+
9 D1−
programmable INT output to indicate error conditions, and 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
MARKING DIAGRAM
throttle a CPU clock.
Features
Optimized for Pentium III
Reduced Guard-banding Software
Automatic Fan Speed Control, Independent of CPU Intervention
1
1031A
RQZ
#YYWW
After Initial Setup
0.125C Resolution on External Temperature Channels
Control Loop to Minimal Acoustic Noise and Battery Consumption
1031ARQZ = Specific Device Code
# = Pb-Free Package
Remote Temperature Measurement Accurate to 1C
Using Remote Diode (Two Channels)
YY = Date Code
WW = Work Week
Local Sensor with 0.25C Resolution
Pulse Width Modulation (PWM) Fan Control for 2 Fans
Programmable PWM Frequency and PWM Duty Cycle
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 31 of this data sheet.
Tach Fan Speed Measurement (Two Channels)
Analog Input to Measure Fan Speed of 2-wire Fans
Programmable INT Output Pin
(Using Sense Resistor)
2-wire System Management Bus (SMBus) with ARA
Configurable Offsets for Temperature Channels 3.0 V
to 5.5 V Supply Range
Support
Overtemperature THERM Output Pin for CPU
Throttling
Shutdown Mode to Minimize Power Consumption
Limit Comparison of All Monitored Values
This is a Pb-Free Device
Applications
Notebook PCs, Network Servers, and Personal
Computers
Telecommunications Equipment
Semiconductor Components Industries, LLC, 2012
April, 2012 − Rev. 5
1
Publication Order Number:
ADM1031/D
1 page  
ADM1031
TYPICAL PERFORMANCE CHARACTERISTICS
15
10
5
DXP TO GND
0
−5 DXP TO VCC (3.3 V)
−10
−15
−20
1
3.3 10 30 100
LEAKAGE RESISTANCE (MW)
Figure 3. Temperature Error vs. PCB Track
Resistance
7
6
5
4
3 VIN = 40 mV p−p
2
1
0
−1 VIN = 20 mV p−p
0 100k 1M 100M 200M 300M 400M 500M
FREQUENCY (Hz)
Figure 5. Temperature Error vs. Common-mode
Noise Frequency
17
15 VIN = 100 mV p−p
13
11
9
7
5
3
1
−1
0
VIN = 200 mV p−p
500k 2M 4M 6M 10M 100M 400M
FREQUENCY (Hz)
Figure 4. Temperature Error vs. Power Supply
Noise Frequency
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)
Figure 6. Pentium) III Temperature Measurement
vs. ADM1031 Reading
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
47
DXP, DXN CAPACITANCE (nF)
Figure 7. Temperature Error vs. Capacitance
between D+ and D–
110
100
90
80
70
60 VCC = 5 V
50
40
30
20 VCC = 3.3 V
10
0
0 1 5 10 25 50 75 100 250 500 750 1000
SCLK FREQUENCY (kHz)
Figure 8. Standby Current vs. Clock Frequency
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5 Page 
ADM1031
environment, a capacitor of value up to 1000 pF can be
placed between the D+ and D– inputs to filter the noise.
To measure DVBE, the sensor is switched between
operating currents of I and N I. The resulting waveform is
passed through a 65 kHz low-pass filter to remove noise,
then to a chopper-stabilized amplifier that performs the
functions of amplification and rectification of the waveform
to produce a dc voltage proportional to DVBE. This voltage
is measured by the ADC to give a temperature output in
11-bit twos complement format. To further reduce the
effects of noise, digital filtering is performed by averaging
the results of 16 measurement cycles. An external
temperature measurement nominally takes 9.6 ms.
Layout Considerations
Digital boards can be electrically noisy environments and
care must be taken to protect the analog inputs from noise,
particularly when measuring the very small voltages from a
remote diode sensor. The following precautions should be
taken:
1. Place the ADM1031 as close as possible to the
remote sensing diode. Provided that the worst
noise sources such as clock generators,
data/address buses, and CRTs are avoided, this
distance can be 4 to 8 inches.
2. Route the D+ and D– tracks close together, in
parallel, with grounded guard tracks on each side.
Provide a ground plane under the tracks if possible.
3. Use wide tracks to minimize inductance and
reduce noise pickup. Ten mil track minimum
width and spacing is recommended.
GND
D+
D−
GND
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
Figure 19. Arrangement of Signal Tracks
4. Try to minimize the number of copper/solder
joints, which can cause thermocouple effects.
Where copper/solder joints are used, make sure
that they are in both the D+ and D– path and at the
same temperature.
Thermocouple effects should not be a major
problem as 1C corresponds to about 200 mV, and
thermocouple voltages are about 3 mV/C of
temperature difference. Unless there are two
thermocouples with a big temperature differential
between them, thermocouple voltages should be
much less than 200 mV.
5. Place a 0.1 mF bypass capacitor close to the
ADM1031.
6. If the distance to the remote sensor is more than
8 inches, the use of twisted pair cable is
recommended. This works up to about 6 to 12 feet.
7. For extra long distances (up to 100 feet), use a
shielded twisted pair cable, such as the Belden #8451
microphone cable. Connect the twisted pair to D+
and D– and the shield to GND close to the
ADM1031. Leave the remote end of the shield
unconnected to avoid ground loops.
Because the measurement technique uses switched
current sources, excessive cable and/or filter capacitance
can affect the measurement. When using long cables, the
filter capacitor C1 can be reduced or removed. In any case
the total shunt capacitance should not exceed 1000 pF.
Cable resistance can also introduce errors. One ohm series
resistance introduces about 0.5C error.
Addressing the Device
ADD (Pin 13) is a three-state input. It is sampled, on
powerup to set the lowest two bits of the serial bus address.
Up to three addresses are available to the systems designer
via this address pin. This reduces the likelihood of conflicts
with other devices attached to the system management bus.
The Interrupt System
The ADM1031 has two interrupt outputs, INT and
THERM. These have different functions. INT responds to
violations of software programmed temperature limits and
is maskable.
THERM is intended as a “fail-safe” interrupt output that
cannot be masked. If the temperature is below the low
temperature limit, the INT pin is asserted low to indicate an
out-of-limit condition. If the temperature exceeds the high
temperature limit, the INT pin is also asserted low. A third
limit, THERM limit, can be programmed into the device to
set the temperature limit above which the overtemperature
THERM pin is asserted low. The behavior of the high limit
and THERM limit is as follows:
1. Whenever the temperature measured exceeds the
high temperature 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, then the fans do not run
full-speed. The THERM limit can 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 can 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, then
the fan runs full-speed whenever THERM is
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| PDF Descargar | [ Datasheet ADM1031.PDF ] | |
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