a
Low-Cost PC Temperature
Monitor and Fan Control ASIC
ADM1022
FEATURES
External Temperature Measurement with Remote
Diode (Two Channels)
On-Chip Temperature Sensor
Interrupt and Over-Temperature Outputs
Fault Tolerant Fan Control
Brownout Detection
LDCM Support
System Management Bus (SMBus)
Standby Mode to Minimize Power Consumption
Limit Comparison of all Monitored Values
GENERAL DESCRIPTION
The ADM1022 is a low cost temperature monitor and fan controller for microprocessor-based systems. The temperature of one
or two remote sensor diodes may be measured, allowing monitoring of processor temperature in single- or dual-processor systems.
Measured values can be read out via a serial System Management Bus, and values for limit comparisons can be programmed
in over the same serial bus.
The ADM1022 also contains a DAC for fan speed control.
Automatic hardware temperature trip points are provided and
the fan will be driven to full speed if they are exceeded.
APPLICATIONS
Network Servers and Personal Computers
Microprocessor-Based Office Equipment
Test Equipment and Measuring Instruments
Finally, the chip has two supply voltage monitors for brownout
detection.
The ADM1022’s 3.0 V to 5.5 V supply voltage range, low supply
current, and SMBus interface make it ideal for a wide range of
applications. These include hardware monitoring and protection
applications in personal computers, electronic test equipment
and office electronics.
FUNCTIONAL BLOCK DIAGRAM
VCC VMON
ADD/NTEST_OUT
RESET
GENERATOR 1
RST1
RST2
VCC
RESET
GENERATOR 2
20k⍀
MR
BANDGAP
TEMPERATURE
SENSOR
D1+
D1–
D2+/GPI
ADM1022
SDA
SCL
ANALOG
OUTPUT
REGISTER
AND 8-BIT DAC
ADDRESS
POINTER
REGISTER
ADC
ANALOG
MULTIPLEXER
SERIAL BUS
INTERFACE
2.5V
BANDGAP
REFERENCE
D2–/THERM
FAN_SPD/NTEST_IN
VALUE AND
LIMIT
REGISTERS
LIMIT
COMPARATORS
INTERRUPT
STATUS
REGISTERS
INT MASK
REGISTER
INT
MASK
GATING
CONFIGURATION
REGISTER
FAN_OFF
GND
REV. B
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reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
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© 2003 Analog Devices, Inc. All rights reserved.
