Analog Devices ADM1021A d Datasheet
Low-Cost Microprocessor
a
FEATURES
Alternative to the ADM1021
On-Chip and Remote Temperature Sensing
No Calibration Necessary
1ⴗC Accuracy for On-Chip Sensor
3ⴗC Accuracy for Remote Sensor
Programmable Overtemperature/Undertemperature
Limits
Programmable Conversion Rate
2-Wire SMBus Serial Interface
Supports System Management Bus (SMBus) Alert
200 mA Max Operating Current
1 mA Standby Current
3 V to 5.5 V Supply
Small 16-Lead QSOP Package
APPLICATIONS
Desktop Computers
Notebook Computers
Smart Batteries
Industrial Controllers
Telecom Equipment
Instrumentation
System Temperature Monitor
*
ADM1021A
PRODUCT DESCRIPTION
The ADM1021A is a two-channel digital thermometer and
undertemperature/overtemperature 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 PNP transistor, which
may be provided on-chip in the case of the Pentium
processors, or can be a low-cost discrete NPN/PNP device such
as the 2N3904/2N3906. 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 ADM1021A communicates over a two-wire serial interface
compatible with SMBus
standards. Undertemperature and
overtemperature 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.
®
III or similar
D+
D–
*Patents Pending
ON-CHIP TEMP.
SENSOR
ANALOG MUX
EXTERNAL DIODE OPEN-CIRCUIT
ADM1021A
NC
NC GND NC NC
V
DD
LOCAL TEMPERATURE
VALUE REGISTER
A-TO-D
CONVERTER
BUSY RUN/STANDBY
REMOTE TEMPERATURE
VALUE REGISTER
GND
FUNCTIONAL BLOCK DIAGRAM
LOCAL TEMPERATURE
LOW LIMIT COMPARATOR
LOCAL TEMPERATURE
HIGH LIMIT COMPARATOR
REMOTE TEMPERATURE
LOW LIMIT COMPARATOR
REMOTE TEMPERATURE
HIGH LIMIT COMPARATOR
STATUS REGISTER
SMBUS INTERFACE
NC
SDATA
SCLK ADD0 ADD1
ADDRESS POINTER
REGISTER
ONE-SHOT
REGISTER
CONVERSION RATE
REGISTER
LOCAL TEMPERATURE
LOW LIMIT REGISTER
LOCAL TEMPERATURE
HIGH LIMIT REGISTER
REMOTE TEMPERATURE
LOW LIMIT REGISTER
REMOTE TEMPERATURE
HIGH LIMIT REGISTER
CONFIGURATION
REGISTER
INTERRUPT
MASKING
NC = NO CONNECT
STBY
ALERT
REV. D
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 owners.
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 © 2004 Analog Devices, Inc. All rights reserved.
ADM1021A–SPECIFICATIONS
(TA = T
MIN
1
to T
, VDD = 3.0 V to 3.6 V, unless otherwise noted.)
MAX
Parameter Min Typ Max Unit 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
= 60°C to 100°C
A
–5 +5 °C
Supply Voltage Range 3 3.6 V Note 2
Undervoltage Lockout Threshold 2.5 2.7 2.95 V V
Undervoltage Lockout Hysteresis 25 mV
Power-On Reset Threshold 0.9 1.7 2.2 V V
Input, Disables ADC, Rising Edge
DD
, Falling Edge
DD
3
POR Threshold Hysteresis 50 mV
Standby Supply Current 1 5 µAV
= 3.3 V, No SMBus Activity
DD
4 µA SCLK at 10 kHz
Average Operating Supply Current 130 200 µA 0.25 Conversions/Sec Rate
Autoconvert Mode, Averaged Over 4 Seconds 225 330 µA2 Conversions/Sec Rate
Conversion Time 65 115 170 ms From Stop Bit to Conversion Complete
(Both Channels)
D+ Forced to D– + 0.65 V
Remote Sensor Source Current 120 205 300 µAHigh Level
71216µALow Level
3
3
D-Source Voltage 0.7 V
Address Pin Bias Current (ADD0, ADD1) 50 µAMomentary at Power-On Reset
SMBUS INTERFACE
Logic Input High Voltage, V
IH
2.2 V VDD = 3 V to 5.5 V
STBY, SCLK, SDATA
Logic Input Low Voltage, V
IL
0.8 V VDD = 3 V to 5.5 V
STBY, SCLK, SDATA
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
, I
IH
IL
–1 +1 µA
SMBus Input Capacitance, SCLK, SDATA 5 pF
SMBus Clock Frequency 100 kHz
SMBus Clock Low Time, t
SMBus Clock High Time, t
SMBus Start Condition Setup Time, t
LOW
HIGH
SU:STA
4.7 µst
4 µst
4.7 µs
between 10% Points
LOW
between 90% Points
HIGH
SMBus Repeat Start Condition 250 ns Between 90% and 90% Points
Setup Time, t
SMBus Start Condition Hold Time, t
SMBus Stop Condition Setup Time, t
SU:STA
HD:STA
SU:STO
4 µsTime from 10% of SDATA to 90% of SCLK
4 µsTime from 90% of SCLK to 10% of SDATA
SMBus Data Valid to SCLK 250 ns Time from 10% or 90% of SDATA to 10%
Rising Edge Time, t
SU:DAT
SMBus Data Hold Time, t
SMBus Bus Free Time, t
BUF
HD:DAT
0 µs
4.7 µsBetween Start/Stop Conditions
of SCLK
SCLK Falling Edge to SDATA 1 µsMaster Clocking in Data
Valid Time, t
NOTES
1
T
= 100°C; T
MAX
2
Operation at VDD = 5 V guaranteed by design, not production tested.
3
Guaranteed by design, not production tested.
Specifications subject to change without notice.
MIN
VD, DAT
= 0°C.
–2–
REV. D
ADM1021A
TOP VIEW
(Not to Scale)
NC = NO CONNECT
NC
V
DD
D+
D–
NC
ADD1
GND
GND
NC
STBY
SCLK
NC
SDATA
ALERT
ADD0
NC
ADM1021A
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
ABSOLUTE MAXIMUM RATINGS*
Positive Supply Voltage (VDD) to GND . . . . . . –0.3 V to +6 V
D+, ADD0, ADD1 . . . . . . . . . . . . . . . –0.3 V to V
+ 0.3 V
DD
D– to GND . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +0.6 V
SCLK, SDATA, ALERT, STBY . . . . . . . . . . . –0.3 V to +6 V
Input Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 50 mA
Input Current, D– . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 1 mA
ESD Rating, All Pins (Human Body Model) . . . . . . . . 2000 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
max) . . . . . . . . . . 150°C
J
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature, (Soldering 10 sec) . . . . . . . . . . . . . 300°C
IR Reflow Peak Temperature . . . . . . . . . . . . . . . . . . . . . 220°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
16-Lead QSOP Package: θ
= 150°C/W.
JA
ORDERING GUIDE
PIN FUNCTION DESCRIPTIONS
Pin No. Mnemonic Description
1, 5, 9, 13, 16 NC No Connect
2V
DD
Positive Supply, 3 V to 5.5 V
3D+Positive Connection to Remote
Temperature Sensor
4D–Negative Connection to Remote
Temperature Sensor
6ADD1 Three-State Logic Input, Higher
Bit of Device Address
7, 8 GND Supply 0 V Connection
10 ADD0 Three-State Logic Input, Lower
Bit of Device Address
11 ALERT Open-Drain Logic Output Used as
Interrupt or SMBus Alert
12 SDATA Logic Input/Output, SMBus Serial
Data. Open-Drain Output.
14 SCLK Logic Input, SMBus Serial Clock
15 STBY Logic Input Selecting Normal
Operation (High) or Standby Mode
(Low)
PIN CONFIGURATION
Model Temperature Package Package
Range Description Option
ADM1021AARQ 0°C to 100°C 16-Lead QSOP RQ-16
ADM1021AARQ-REEL 0°C to 100°C 16-Lead QSOP RQ-16
ADM1021AARQ-REEL7 0°C to 100°C 16-Lead QSOP RQ-16
ADM1021AARQZ* 0°C to 100°C 16-Lead QSOP RQ-16
ADM1021AARQZ-REEL* 0°C to 100°C 16-Lead QSOP RQ-16
ADM1021AARQZ-REEL7* 0°C to 100°C 16-Lead QSOP RQ-16
EVAL-ADM1021AEB Evaluation Board
* Z = Pb-Lead free
t
R
t
HD;DAT
t
HIGH
t
F
SCL
SDA
t
LOW
t
HD;STA
t
BUF
S
P
Figure 1. Diagram for Serial Bus Timing
t
SU;DAT
t
SU;STA
t
HD;STA
t
SU;STO
PS
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
ADM1021A 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. D
–3–
ADM1021A–Typical Performance Characteristics
20
15
10
5
0
–5
–10
–15
TEMPERATURE ERROR – ⴗC
–20
–25
–30
D+ TO GND
D+ TO V
DD
LEAKAGE RESISTANCE – M⍀
101
100
2
1
–1
TEMPERATURE ERROR – ⴗC
–2
–3
60070
50
80
TEMPERATURE – ⴗC
UPPER SPEC LEVEL
DEV10
LOWER SPEC LEVEL
100
90
110
120
TPC 1. Temperature Error vs. PC Board Track Resistance
5
4
250mV p-p REMOTE
3
2
TEMPERATURE ERROR – ⴗC
1
0
100
100mV p-p REMOTE
FREQUENCY – Hz
100M1k 10k 100k 1M 10M
TPC 2. Temperature Error vs. Power Supply Noise
Frequency
9
8
7
6
5
4
3
TEMPERATURE ERROR – ⴗC
2
1
0
10 1k 10k
1
100 100k 1M
100mV p-p
50mV p-p
FREQUENCY – Hz
25mV p-p
10M 100M
TPC 4. Temperature Error of ADM1021A vs. Pentium
III Temperature
14
12
10
8
6
4
2
TEMPERATURE ERROR – ⴗC
0
–1
2
4681012141618202224
CAPACITANCE – nF
TPC 5. Temperature Error vs. Capacitance Between D+
and D–
70
60
50
40
30
20
SUPPLY CURRENT – A
10
0
1
510255075100 1000250 500 750
SCLK FREQUENCY – kHz
VDD = 3.3V
VDD = 5V
TPC 3. Temperature Error vs. Common-Mode Noise
Frequency
–4–
TPC 6. Standby Supply Current vs. Clock Frequency
REV. D
ADM1021A
TIME – Seconds
TEMPERATURE – ⴗC
0
25
50
75
100
125
REMOTE
TEMPERATURE
INT
TEMPERATURE
023456789101
4
3
10mV p-p
2
1
TEMPERATURE ERROR – ⴗC
0
100k 1M
10M 100M 1G
FREQUENCY – Hz
TPC 7. Temperature Error vs. Differential-Mode Noise
Frequency
550
500
450
400
350
300
250
200
SUPPLY CURRENT – A
150
100
50
0.125
0.25 0.5 8
CONVERSION RATE – Hz
3.3V
5V
40.0625
21
100
80
60
40
20
SUPPLY CURRENT – A
0
–20
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE – V
TPC 9. Standby Supply Current vs. Supply Voltage
TPC 8. Operating Supply Current vs. Conversion Rate
FUNCTIONAL DESCRIPTION
The ADM1021A contains a two-channel A-to-D converter with
special input-signal conditioning to enable operation with remote and
on-chip diode temperature sensors. When the ADM1021A is operating normally, the A-to-D converter operates in a free-running mode.
The analog input multiplexer alternately selects either the on-chip
temperature sensor to measure its local temperature, or the remote
temperature sensor. These signals are digitized by the ADC and
the results stored in the Local and Remote Temperature Value
Registers as 8-bit, twos complement words.
The measurement results are compared with local and remote,
high and low temperature limits, stored in four on-chip registers.
Out-of-limit comparisons generate flags that are stored in the
status register, and one or more out-of-limit results will cause
the ALERT output to pull low.
The limit registers can be programmed, and the device controlled and configured, via the serial System Management Bus.
The contents of any register can also be read back via the SMBus.
Control and configuration functions consist of:
•
Switching the device between normal operation and standby
mode.
•
Masking or enabling the ALERT output.
•
Selecting the conversion rate.
On initial power-up, the remote and local temperature values
default to –128°C. Since the device normally powers up converting,
a measurement of local and remote temperature is made and these
values are then stored before a comparison with the stored limits
is made. However, if the part is powered up in standby mode
(STBY pin pulled low), no new values are written to the register
before a comparison is made. As a result, both RLOW and LLOW
are tripped in the Status Register, thus generating an ALERT out-
put. This may be cleared in one of two ways:
1. Change both the local and remote lower limits to –128°C
and read the status register (which in turn clears the ALERT
output).
2. Take the part out of standby and read the status register
(which in turn clears the ALERT output). This will work only
if the measured values are within the limit values.
MEASUREMENT METHOD
A simple method of measuring temperature is to exploit the
negative temperature coefficient of a diode, or the base-emitter
voltage of a transistor, operated at constant current. Unfortunately, this technique requires calibration to null out the effect
of the absolute value of V
TPC 10. Response to Thermal Shock
, which varies from device to device.
BE
REV. D
–5–
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