a
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
Intelligent Temperature Monitor
and Dual PWM Fan Controller
ADM1031
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
V
CC
ADD
ADM1031
SLAVE
ADDRESS
REGISTER
FAN FILTER
REGISTER
FAN
CHARACTERISTICS
REGISTERS
SERIAL BUS
INTERFACE
ADDRESS
POINTER
REGISTER
SDA
SCL
INT (SMBALERT)
INTERRUPT
STATUS
REGISTERS
LIMIT
COMPARATOR
FAN_FAULT
VALUE AND LIMIT
REGISTERS
OFFSET
REGISTERS
CONFIGURATION
REGISTERS
THERM
PWM_OUT1
PWM_OUT2
TACH2 /AIN2
TACH1 /AIN1
D1+
D1–
D2+
D2–
PWM
CONTROLLERS
FAN SPEED
CONFIG
REGISTER
FAN SPEED
COUNTER
TACH SIGNAL
CONDITIONING
ANALOG
MULTIPLEXER
ADC
*Patents
pending.
BANDGAP
TEMPERATURE
SENSOR
2.5V
BANDGAP
REFERENCE
REV. A
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 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.
GND
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
© 2003 Analog Devices, Inc. All rights reserved.
ADM1031–SPECIFICATIONS
Parameter
POWER SUPPLY
Supply Voltage, V
CC
Supply Current, I
CC
TEMPERATURE-TO-DIGITAL CONVERTER
Local Sensor Accuracy
Resolution
Remote Diode1 Sensor Accuracy
Remote Diode2 Sensor Accuracy
Resolution
Remote Sensor Source Current
OPEN-DRAIN DIGITAL OUTPUTS
(THERM,
INT, FAN_FAULT,
PWM_OUT)
Output Low Voltage, V
OL
High-Level Output Leakage Current, I
OH
OPEN-DRAIN SERIAL DATA BUS OUTPUT (SDA)
Output Low Voltage, V
OL
High-Level Output Leakage Current, I
OH
SERIAL BUS DIGITAL INPUTS (SCL, SDA)
Input High Voltage, V
IH
Input Low Voltage, V
IL
Hysteresis
DIGITAL INPUT LOGIC LEVELS
2
(ADD,
THERM,
TACH1/2)
Input High Voltage, V
IH
Input Low Voltage, V
IL
DIGITAL INPUT LEAKAGE CURRENT
Input High Current, I
IH
Input Low Current, I
IL
Input Capacitance, C
IN
FAN RPM-TO-DIGITAL CONVERTER
Accuracy
Full-Scale Count
TACH Nominal Input RPM
1
(T
A
= T
MIN
to T
MAX
, V
CC
= V
MIN
to V
MAX
, unless otherwise noted.)
Typ
3.30
1.4
32
±
1
0.25
±
0.5
±
0.5
0.125
180
11
Max
5.5
3
50
±
3
±
1
±
1.75
Unit
V
mA
µA
°C
°C
°C
°C
°C
µA
µA
Test Conditions/Comments
Min
3.0
Interface Inactive, ADC Active
Standby Mode
60°C
≤
T
D
≤
100°C
60°C
≤
T
D
≤
100°C
High Level
Low Level
0.1
0.4
1
0.4
1
V
µA
V
µA
V
V
mV
I
OUT
= –6.0 mA; V
CC
= 3 V
V
OUT
= V
CC
; V
CC
= 3 V
I
OUT
= –6.0 mA; V
CC
= 3 V
V
OUT
= V
CC
0.1
2.1
0.8
500
2.1
0.8
–1
1
5
±
6
255
4400
2200
1100
550
637
10
50
4.7
4.7
4
4
1.3
4
100
V
V
µA
µA
pF
%
RPM
RPM
RPM
RPM
ms
kHz
ns
µs
µs
µs
µs
µs
µs
ns
ns
ns
ns
V
IN
= V
CC
V
IN
= 0
60°C
≤
T
A
≤
100°C
Divisor
Divisor
Divisor
Divisor
N
N
N
N
=
=
=
=
1,
2,
4,
8,
Fan
Fan
Fan
Fan
Count
Count
Count
Count
=
=
=
=
153
153
153
153
Conversion Cycle Time
SERIAL BUS TIMING
3
Clock Frequency, f
SCLK
Glitch Immunity, t
SW
Bus Free Time, t
BUF
Start Setup Time, t
SU;STA
Start Hold Time, t
HD;STA
Stop Condition Setup Time t
SU;STO
SCL Low Time, t
LOW
SCL High Time, t
HIGH
SCL, SDA Rise Time, t
R
SCL, SDA Fall Time, t
F
Data Setup Time, t
SU;DAT
Data Hold Time, t
HD;DAT
50
1000
300
250
300
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
See Figure 1
NOTES
1
Typicals are at T
A
= 25°C and represent most likely parametric norm. Shutdown current typ is measured with V
CC
= 3.3 V.
2
ADD is a three-state input that may be pulled high, low or left open-circuit.
3
Timing specifications are tested at logic levels of V
IL
= 0.8 V for a falling edge and V
IH
= 2.2 V for a rising edge.
Specifications subject to change without notice.
–2–
REV. A
ADM1031
ABSOLUTE MAXIMUM RATINGS*
ORDERING GUIDE
Positive Supply Voltage (V
CC
) . . . . . . . . . . . . . . . . . . . . .6.5 V
Voltage on Any Input or Output Pin . . . . . . . . –0.3 V to +6.5 V
Input Current at Any Pin . . . . . . . . . . . . . . . . . . . . . . .
±
5 mA
Package Input Current . . . . . . . . . . . . . . . . . . . . . . .
±
20 mA
Maximum Junction Temperature (T
JMAX
) . . . . . . . . . . 150°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature, Soldering
Vapor Phase 60 sec . . . . . . . . . . . . . . . . . . . . . . . . . . 215°C
Infrared 15 sec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200°C
ESD Rating All Pins . . . . . . . . . . . . . . . . . . . . . . . . . . 2000 V
*Stresses
above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
Model
ADM1031ARQ
Temperature
Range
0°C to 100°C
Package
Description
Package
Option
16-Lead QSOP RQ-16
THERMAL CHARACTERISTICS
16-Lead QSOP Package
θ
JA
= 105°C/W,
θ
JC
= 39°C/W
t
R
t
F
t
HD:STA
t
LOW
SCL
t
HD:STA
SDA
t
HD:DAT
t
HIGH
t
SU:DAT
t
SU:STA
t
SU:STO
t
BUF
P
S
S
P
Figure 1. Diagram for Serial Bus Timing
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the ADM1031 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
REV. A
–3–
ADM1031
PIN FUNCTION DESCRIPTIONS
Pin No.
1
2
3
4
5
6
7
Mnemonic
PWM_OUT1
TACH1/AIN1
PWM_OUT2
TACH2/AIN2
GND
V
CC
THERM
Description
Digital Output (Open-Drain). Pulsewidth modulated output to control fan speed. Requires pull-
up resistor (10 kΩ typical).
Digital/Analog Input. Fan tachometer input to measure FAN1 fan speed. May be reprogrammed as
an analog input to measure speed of a 2-wire fan via a sense resistor (2
Ω
typical).
Digital Output (Open-Drain). Pulsewidth Modulated output to control FAN2 fan speed.
Requires pull-up resistor (10 kΩ typical).
Digital/Analog Input. Fan tachometer input to measure FAN2 fan speed. May be repro-
grammed as an analog input to measure speed of a 2-wire fan via a sense resistor (2
Ω
typical).
System Ground.
Power. Can be powered by 3.3 V Standby power if monitoring in low power states is required.
Digital I/O (Open-Drain). An active low thermal overload output that indicates a violation of a
temperature set point (overtemperature). Also acts as an input to provide external fan control.
When this pin is pulled low by an external signal, a status bit is set, and the fan speed is set to
full-on. Requires pull-up resistor (10 kΩ).
Digital Output (Open-Drain). Can be used to signal a fan fault. Drives second fan to full speed
if one fan fails. Requires pull-up resistor (typically 10 kΩ).
Analog Input. Connected to cathode of first remote temperature-sensing diode. The temperature-
sensing element is either a Pentium III substrate transistor or a general-purpose 2N3904.
Analog Input. Connected to anode of first remote temperature-sensing diode.
Analog Input. Connected to cathode of second remote temperature-sensing diode.
Analog Input. Connected to anode of second remote temperature-sensing diode.
Three-State Logic Input. Sets two lower bits of device SMBus address.
Digital Output (Open-Drain). Can be programmed as an interrupt (SMBus ALERT) output for
temperature/fan speed interrupts. Requires pull-up resistor (10 kΩ typical).
Digital I/O. Serial Bus Bidirectional Data. Open-drain output. Requires pull-up resistor
(2.2 kΩ typical).
Digital Input. Serial Bus Clock. Requires pull-up resistor (2.2 kΩ typical).
8
9
10
11
12
13
14
15
16
FAN_FAULT
D1–
D1+
D2–
D2+
ADD
INT
(SMBALERT)
SDA
SCL
PIN CONFIGURATION
PWM_OUT1
1
TACH1/AIN1
2
16
15
SCL
SDA
INT(SMBALERT)
PWM_OUT2
3
TACH2/AIN2
4
ADM1031
14
13
ADD
TOP VIEW
GND
5
(Not to Scale)
12
D2+
V
CC
6
THERM
7
FAN_FAULT
8
11
10
9
D2–
D1+
D1–
–4–
REV. A
Typical Performance Characteristics–ADM1031
15
REMOTE TEMPERATURE ERROR – C
10
90
5
0
DXP TO V
CC
(3.3V)
–5
–10
READING – C
110
100
80
DXP TO GND
70
60
50
40
30
20
–15
10
–20
1
3.3
10
30
LEAKAGE RESISTANCE – M
100
0
0
10
20
30
60
40
50
70
80
PIII TEMPERATURE – C
90
100
110
TPC 1. Temperature Error vs. PCB Track Resistance
TPC 4. Pentium III Temperature Measurement vs.
ADM1031 Reading
17
REMOTE TEMPERATURE ERROR – C
13
11
9
7
5
3
1
–1
0
500k
2M
4M
6M
10M
FREQUENCY – Hz
100M
400M
V
IN
= 200mV p-p
REMOTE TEMPERATURE ERROR – C
15
V
IN
= 100mV p-p
1
0
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
–11
–12
–13
–14
–15
–16
1
2.2
3.3
10
4.7
DXP – DXN CAPACITANCE – nF
22
47
TPC 2. Temperature Error vs. Power Supply Noise
Frequency
TPC 5. Temperature Error vs. Capacitance between
D+ and D–
7
REMOTE TEMPERATURE ERROR – C
110
100
90
A
SUPPLY CURRENT –
6
5
4
3
V
IN
= 40mV p-p
2
1
0
V
IN
= 20mV p-p
–1
0
100k
1M
300M
100M 200M
FREQUENCY – Hz
400M
500M
80
70
60
50
40
30
20
10
0
0
1
5
10
75 100 250
25
50
SCLK FREQUENCY – kHz
500
750 1000
V
CC
= 3.3V
V
CC
= 5V
TPC 3. Temperature Error vs. Common-Mode Noise
Frequency
TPC 6. Standby Current vs. Clock Frequency
REV. A
–5–
stm32/stm8
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