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ADM1031 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADM1031
Beschreibung Intelligent Temperature Monitor and Dual PWM Fan Controller
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 30 Seiten
ADM1031 Datasheet, Funktion
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






ADM1031 Datasheet, Funktion
ADM1031
7
VIN = 30mV p-p
6
5
4
3
2
1
0 VIN = 20mV p-p
1
0
100k 1M 100M 200M 300M 400M 500M
FREQUENCY Hz
TPC 7. Temperature Error vs. Differential-Mode Noise
Frequency
200
180
160
140
120
100
80
60
40
20
0
20
0
ADD = Hi-Z
ADD = GND
ADD = VCC
1.1 1.3 1.5 1.7 1.9 2.1 2.5 2.9 4.5
SUPPLY VOLTAGE V
TPC 8. Standby Supply Current vs. Supply Voltage
0.08
0
0.08
0.16
0.24
0.32
0.40
0.48
0.56
0.64
0.72
0.80
0
20 40 60
80 85 100 105 120
TEMPERATURE ؇C
TPC 9. Local Sensor Temperature Error
0.08
0
0.08
0.16
0.24
0.32
0.40
0.48
0.56
0.64
0.72
0.80
0
20 40 60
80 85 100 105 120
TEMPERATURE ؇C
TPC 10. Remote Temperature Sensor Error
1.30
1.25
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0
SUPPLY VOLTAGE V
TPC 11. Supply Current vs. Supply Voltage
120
110
100
90
80
70
60
50
40
30
20
10
0
012 34 5 6 7 89
TIME Sec
TPC 12. Response to Thermal Shock
10
–6– REV. 0

6 Page









ADM1031 pdf, datenblatt
ADM1031
AUTOMATIC FAN SPEED CONTROL
The ADM1031 has a local temperature channel and two remote
temperature channels, which may be connected to an on-chip
diode-connected transistor on a CPU. These three temperature
channels may be used as the basis for an automatic fan speed
control loop to drive fans using Pulsewidth Modulation (PWM).
HOW DOES THE CONTROL LOOP WORK?
The Automatic Fan Speed Control Loop is shown in Figure 6.
MAX
SPIN-UP FOR TWO SECONDS
FAN
SPEED
MIN
TMIN
TMAX = TMIN + TRANGE
TEMPERATURE
Figure 6. Automatic Fan Speed Control
In order for the fan speed control loop to work, certain loop
parameters need to be programmed into the device.
1. TMIN. The temperature at which the fan should switch on
and run at minimum speed. The fan will only turn on once
the temperature being measured rises above the TMIN value
programmed. The fan will spin up for a predetermined time
(default = 2 secs). See Fan Spin-Up section for more details.
2. TRANGE. The temperature range over which the ADM1031
will automatically adjust the fan speed. As the temperature
increases beyond TMIN, the PWM_OUT duty cycle will be
increased accordingly. The TRANGE parameter actually defines
the fan speed versus temperature slope of the control loop.
3. TMAX. The temperature at which the fan will be at its maxi-
mum speed. At this temperature, the PWM duty cycle driving
the fan will be 100%. TMAX is given by TMIN + TRANGE.
Since this parameter is the sum of the TMIN and TRANGE
parameters, it does not need to be programmed into a
register on-chip.
4. A hysteresis value of 5°C is included in the control loop to
prevent the fan continuously switching on and off if the tem-
perature is close to TMIN. The fan will continue to run until
such time as the temperature drops 5°C below TMIN.
Figure 7 shows the different control slopes determined by the
TRANGE value chosen, and programmed into the ADM1031.
TMIN was set to 0°C to start all slopes from the same point. It
can be seen how changing the TRANGE value affects the PWM
duty cycle versus temperature slope.
100
93
87
80
73
66
60
53
47
40
33
0 5 10
TMIN
= 80؇C
T RANGE
20 40 60 80
TMAX = TMIN + TRANGE
TEMPERATURE ؇C
Figure 7. PWM Duty Cycle vs. Temperature Slopes (TRANGE)
Figure 8 shows how, for a given TRANGE, changing the TMIN
value affects the loop. Increasing the TMIN value will increase
the TMAX (temperature at which the fan runs full speed) value,
since TMAX = TMIN + TRANGE. Note, however, that the PWM
Duty Cycle vs Temperature slope remains exactly the same.
Changing the TMIN value merely shifts the control slope. The
TMIN may be changed in increments of 4°C.
100
93
87
80
73
66
60
53
47
40
33
0
TMIN
20 40 60 80
TMAX = TMIN + TRANGE
TEMPERATURE ؇C
Figure 8. Effect of Increasing TMIN Value on Control Loop
FAN SPIN-UP
As was previously mentioned, once the temperature being mea-
sured exceeds the TMIN value programmed, the fan will turn on
at minimum speed (default = 33% duty cycle). However, the
problem with fans being driven by PWM is that 33% duty cycle
is not enough to reliably start the fan spinning. The solution is
to spin the fan up for a predetermined time, and once the fan
has spun up, its running speed may be reduced in line with the
temperature being measured.
The ADM1031 allows fan spin-up times between 200 ms and
8 seconds. Bits <2:0> of Fan Characteristics Registers 1 and
2 (Register 0x20, 0x21) program the fan spin-up times.
–12–
REV. 0

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