Analog Devices ADM1020 Datasheet
REV. 0
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.
a
ADM1020
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1999
8-Lead, Low-Cost, System
Temperature Monitor
FUNCTIONAL BLOCK DIAGRAM
LOCAL TEMPERATURE
LOW LIMIT COMPARATOR
LOCAL TEMPERATURE
HIGH LIMIT COMPARATOR
REMOTE TEMPERATURE
LOW LIMIT COMPARATOR
REMOTE TEMPERATURE
HIGH LIMIT COMPARATOR
REMOTE TEMPERATURE
VALUE REGISTER
LOCAL TEMPERATURE
VALUE REGISTER
RUN/STANDBY
8-BIT A-TO-D
CONVERTER
BUSY
ANALOG
MUX
ON-CHIP TEMP.
SENSOR
D+
D–
STATUS REGISTER
LOCAL TEMPERATURE
LOW LIMIT REGISTER
LOCAL TEMPERATURE
HIGH LIMIT REGISTER
REMOTE TEMPERATURE
LOW LIMIT REGISTER
REMOTE TEMPERATURE
HIGH LIMIT REGISTER
CONFIGURATION
REGISTER
CONVERSION RATE
REGISTER
ONE-SHOT
REGISTER
ADDRESS POINTER
REGISTER
INTERRUPT
MASKING
ALERT
ADM1020
SMBUS INTERFACE
EXTERNAL DIODE OPEN-CIRCUIT
V
DD
GND SDATA SCLK ADD
PRODUCT DESCRIPTION
The ADM1020 is a two-channel digital thermometer and
under/over temperature alarm, intended for use in personal
computers and other systems requiring thermal monitoring and
management. The device can measure the temperature of a
microprocessor using a diode-connected NPN or PNP transistor, which may be provided on-chip in the case of the Pentium
®
II or similar processors, or can be a low-cost discrete device
such as the 2N3904. A novel measurement technique cancels
out the absolute value of the transistor’s base emitter voltage, so
that no calibration is required. The second measurement channel measures the output of an on-chip temperature sensor, to
monitor the temperature of the device and its environment.
The ADM1020 communicates over a two-wire serial interface
compatible with System Management Bus (SMBus) standards.
Under and over temperature limits can be programmed into the
devices over the serial bus, and an ALERT output signals when
the on-chip or remote temperature is out of range. This output
can be used as an interrupt, or as an SMBus alert.
SMBus is a trademark of Intel Corporation.
Pentium is a registered trademark of Intel Corporation.
FEATURES
On-Chip and Remote Temperature Sensing
No Calibration Necessary
1ⴗC Accuracy for On-Chip Sensor
3ⴗC Accuracy for Remote Sensor
Programmable Over/Under Temperature Limits
Programmable Conversion Rate
2-Wire SMBus™ Serial Interface
Supports SMBus Alert
70 A Max Operating Current
3 A Standby Current
+3 V to +5.5 V Supply
8-Lead SOIC Package
APPLICATIONS
Desktop Computers
Notebook Computers
Smart Batteries
Industrial Controllers
Telecommunication Equipment
Instrumentation
REV. 0–2–
ADM1020–SPECIFICATIONS
(TA = T
MIN
to T
MAX
, VDD = 3.0 V to 3.6 V, unless otherwise noted)
Parameter Min Typ Max Units Test Conditions/Comments
POWER SUPPLY AND ADC
Temperature Resolution 1 °C Guaranteed No Missed Codes
Temperature Error, Local Sensor ±1 °C
–3 +3 °C
Temperature Error, Remote Sensor –3 +3 °CT
A
= +60°C to +100°C
–5 +5 °C
Supply Voltage Range 3 3.6 V Note 1
Undervoltage Lockout Threshold 2.5 2.7 2.95 V V
DD
Input, Disables ADC,
Rising Edge
Undervoltage Lockout Hysteresis 25 mV
Power-On Reset Threshold 0.9 1.7 2.2 V V
DD
, Falling Edge
2
POR Threshold Hysteresis 50 mV
Standby Supply Current 3 10 µAV
DD
= 3.3 V, No SMBus Activity
4 µA SCLK at 10 kHz
Average Operating Supply Current 70 190 µA 0.25 Conversions/Sec Rate
Auto-Convert Mode, Averaged Over 4 Seconds 160 290 µA 2 Conversions/Sec Rate
Conversion Time 65 115 170 ms From Stop Bit to Conversion
Complete (Both Channels)
Remote Sensor Source Current D+ Forced to D– + 0.65 V
90 µA High Level
5.5 µA Low Level
D– Source Voltage 0.7 V
Address Pin Bias Current 50 µA Momentary at Power-On Reset
SMBUS INTERFACE
Logic Input High Voltage, V
IH
STBY, SCLK, SDATA 2.2 V VDD = 3 V to 5.5 V
Logic Input Low Voltage, V
IL
STBY, SCLK, SDATA 0.8 V VDD = 3 V to 5.5 V
SMBus Output Low Sink Current 6 mA SDATA Forced to 0.6 V
ALERT Output Low Sink Current 1 mA ALERT Forced to 0.4 V
Logic Input Current, I
IH
, I
IL
–1 +1 µA
SMBus Input Capacitance, SCLK, SDATA 5 pF
SMBus Clock Frequency 0 100 kHz
SMBus Clock Low Time, t
LOW
4.7 µst
LOW
Between 10% Points
SMBus Clock High Time, t
HIGH
4 µst
HIGH
Between 90% Points
SMBus Start Condition Setup Time, t
SU:STA
4.7 µs
SMBus Repeat Start Condition 250 ns Between 90% and 90% Points
Setup Time, t
SU:STA
SMBus Start Condition Hold Time, t
HD:STA
4 µs Time from 10% of SDATA to
90% of SCLK
SMBus Stop Condition Setup Time, t
SU:STO
4 µs Time from 90% of SCLK to 10%
of SDATA
SMBus Data Valid to SCLK 250 ns Time from 10% or 90% of
Rising Edge Time, t
SU:DAT
SDATA to 10% of SCLK
SMBus Data Hold Time, t
HD:DAT
0 µs
SMBus Bus Free Time, t
BUF
4.7 µs Between Start/Stop Condition
SCLK Falling Edge to SDATA
Valid Time, t
VD,DAT
1 µs Master Clocking in Data
NOTES
1
Operation at VDD = +5 V guaranteed by design, not production tested.
2
Guaranteed by design, not production tested.
Specifications subject to change without notice.
REV. 0
ADM1020
–3–
ABSOLUTE MAXIMUM RATINGS*
Positive Supply Voltage (VDD) to GND . . . . . . . . –0.3 V, +6 V
D+, ADD . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V, V
DD
+ 0.3 V
D– to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . .–0.3 V, +0.6 V
SCLK, SDATA, ALERT . . . . . . . . . . . . . . . . . . . . . –0.3 V, +6 V
Input Current, SDATA . . . . . . . . . . . . . . . . . . . . . –1, ±50 mA
Input Current, D– . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1 mA
ESD Rating, all Pins (Human Body Model) . . . . . . . . 4000 V
Continuous Power Dissipation
Up to +70°C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650 mW
Derating above +70°C . . . . . . . . . . . . . . . . . . . . 6.7 mW/°C
Operating Temperature Range . . . . . . . . . . –55°C to +125°C
Maximum Junction Temperature (T
J
max) . . . . . . . . . +150°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature, Soldering
Vapor Phase 60 sec . . . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared 15 sec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +200°C
*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.
THERMAL CHARACTERISTICS
8-Lead SOIC Package: θ
JA
= 150°C/Watt.
PIN FUNCTION DESCRIPTION
Pin
No. Mnemonic Description
1V
DD
Positive Supply, +3 V to +5.5 V
2 D+ Positive Connection to Emitter of Remote
Temperature Sensor.
3 D– Negative Connection to Base of Remote
Temperature Sensor.
4 ADD Address Select Three-State Logic Input.
5 GND Supply 0 V Connection.
6 ALERT Open-Drain Logic Output Used as
Interrupt or SMBus Alert.
7 SDATA Logic Input/Output, SMBus Serial Data.
Open-Drain Output.
8 SCLK Logic Input, SMBus Serial Clock.
PIN CONFIGURATION
TOP VIEW
(Not to Scale)
8
7
6
5
1
2
3
4
V
DD
D+
D–
ADD
SCLK
SDATA
ALERT
GND
ADM1020
ORDERING GUIDE
Temperature Package Package
Model* Range Description Option
ADM1020AR-REEL 0°C to +85°C 8-Lead Small Outline (SOIC) SO-8
ADM1020AR-REEL7
*REEL contains 2500 pieces; REEL7 contains 1000 pieces.
REV. 0
ADM1020
–4–
LEAKAGE RESISTANCE – MV
30
20
–60
1.0 1003.3
TEMPERATURE ERROR – 8C
10 30
–10
–30
–40
–50
10
0
–20
D+ TO GND
D+ TO VCC (5V)
Figure 1. Temperature Error vs. PC Board Track Resistance
FREQUENCY – Hz
6
–1
50 50M500
TEMPERATURE ERROR – 8C
5k
50k
500k 5M
5
4
3
1
0
2
250mV p-p REMOTE
100mV p-p REMOTE
Figure 2. Temperature Error vs. Power Supply Noise
Frequency
FREQUENCY – Hz
–5
50 50M500
TEMPERATURE ERROR – 8C
5k 50k 500k 5M
25
20
15
5
0
10
25mV p-p
50mV p-p
100mV p-p
Figure 3. Temperature Error vs. Common-Mode Noise
Frequency
MEASURED TEMPERATURE
0 11010
READING
20 30 40 50
120
20
30
0
10
40
50
60
70
80
90
100
60 70 80 90 100
Figure 4. Pentium II Temperature Measurement vs.
ADM1020 Reading
D+ AND D– CAPACITANCE – nF
25
20
–5
1.0 102.2
TEMPERATURE ERROR – 8C
3.2 4.7 7
15
10
5
0
Figure 5. Temperature Error vs. Capacitance Between
D+ and D–
SCLK FREQUENCY – Hz
80
30
0
0
1M1k
SUPPLY CURRENT – mA
5k 10k 25k 50k 75k 100k 250k 500k 750k
70
40
20
10
60
50
VCC = +5V
VCC = +3V
Figure 6. Standby Supply Current vs. Clock Frequency
–Typical Performance Characteristics
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