ADM1031 Ver la hoja de datos (PDF) - Analog Devices
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ADM1031 Datasheet PDF : 32 Pages
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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
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