ADM1031
PIN ASSIGNMENT
Pin No.
Mnemonic
1
PWM_OUT1
2
TACH1/AIN1
3
PWM_OUT2
4
TACH2/AIN2
5
GND
6
VCC
7
THERM
8
FAN_FAULT
9
D1–
10
D1+
11
D2–
12
D2+
13
ADD
14
INT(SMBALERT)
15
SDA
16
SCL
Description
Digital Output, Open−Drain. Pulse width modulated output to control fan speed. Requires pullup
resistor (10 kW typical).
Digital/Analog Input. Fan tachometer input to measure FAN1 fan speed. Can be reprogrammed as an
analog input to measure speed of a 2−wire fan via a sense resistor (2 W typical).
Digital Output, Open−Drain. Pulse width modulated output to control FAN2 fan speed. Requires
pullup resistor (10 kW typical).
Digital/Analog Input. Fan tachometer input to measure FAN2 fan speed. Can be reprogrammed as an
analog input to measure speed of a 2−wire fan via a sense resistor (2 W 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 pullup resistor (10 kW).
Digital Output, Open−Drain. Can be used to signal a fan fault. Drives second fan to full speed if one
fan fails. Requires pullup resistor (typically 10 kW).
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 pullup resistor (10 kW typical).
Digital I/O, Serial Bus Bidirectional Data. Open−drain output. Requires pullup resistor (2.2 kW typical).
Digital Input, Serial Bus Clock. Requires pullup resistor (2.2 kW typical).
ELECTRICAL CHARACTERISTICS TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted. (Note 1)
Parameter
Test Conditions/Comments
Min
Typ
Max Unit
POWER SUPPLY
Supply Voltage, VCC
Supply Current, ICC
Interface inactive, ADC active
Standby mode
3.0
3.3
3.6
V
1.4
3.0
mA
32
50
mA
TEMPERATURE−TO−DIGITAL CONVERTER
Local Sensor Accuracy
±1.0 ±3.0
°C
Resolution
0.25
°C
Remote Diode1 Sensor Accuracy
Remote Diode2 Sensor Accuracy
Resolution
60°C ≤ TD ≤ 100°C
60°C ≤ TD ≤ 100°C
±0.5 ±1.0
°C
±0.5 ±1.75
°C
0.125
°C
Remote Sensor Source Current
High level
Low level
180
mA
11
OPEN−DRAIN DIGITAL OUTPUTS (THERM, INT, FAN_FAULT, PWM_OUT)
Output Low Voltage, VOL
High−Level Output Leakage Current, IOH
IOUT = –6.0 mA; VCC = 3.0 V
VOUT = VCC; VCC = 3.0 V
0.4
V
0.1
1.0
mA
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