Voltage Output Temperature Sensor
with Signal Conditioning
AD22100
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.
Specifications subject to change without notice. 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.
FEATURES
200°C temperature span
Accuracy better than ±2% of full scale
Linearity better than ±1% of full scale
Temperature coefficient of 22.5 mV/°C
Output proportional to temperature × V+
Single-supply operation
Reverse voltage protection
Minimal self-heating
High level, low impedance output
APPLICATIONS
HVAC systems
System temperature compensation
Board level temperature sensing
Electronic thermostats
MARKETS
Industrial process control
Instrumentation
Automotive
GENERAL DESCRIPTION
The AD221001 is a monolithic temperature sensor with on-chip
signal conditioning. It can be operated over the temperature
range −50°C to +150°C, making it ideal for use in numerous
HVAC, instrumentation, and automotive applications.
The signal conditioning eliminates the need for any trimming,
buffering, or linearization circuitry, greatly simplifying the
system design and reducing the overall system cost.
The output voltage is proportional to the temperature x the
supply voltage (ratiometric). The output swings from 0.25 V at
−50°C to +4.75 V at +150°C using a single +5.0 V supply.
Due to its ratiometric nature, the AD22100 offers a cost-
effective solution when interfacing to an analog-to-digital
converter. This is accomplished by using the ADC’s +5 V
power supply as a reference to both the ADC and the AD22100
eliminating the need for and cost of a precision reference (see
Figure 2).
1 Protected by U.S. Patent No. 5,030,849 and 5,243,319.
FUNCTIONAL BLOCK DIAGRAM
V+
V
OUT
R
T
00673-C-001
Figure 1.
AD22100
+5V
REFERENCE
ANALOG-TO-
DIGITAL
CONVERTER
INPUT
1kΩ
V
O
SIGNAL OUTPUT
DIRECT TO ADC
0.1µF
–50°C TO +150°C
00673-C-002
Figure 2. Application Circuit
AD22100
Rev. D | Page 2 of 12
TABLE OF CONTENTS
Specifications..................................................................................... 3
Chip Specifications....................................................................... 3
Absolute Maximum Ratings............................................................ 4
ESD Caution.................................................................................. 4
Pin Configurations and Function Descriptions ........................... 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ........................................................................ 7
Absolute Accuracy and Nonlinearity Specifications ............... 7
Output Stage Considerations.......................................................7
Ratiometricity Considerations ....................................................8
Mounting Considerations ............................................................8
Thermal Environment Effects .....................................................8
Microprocessor A/D Interface Issues .........................................9
Use with a Precision Reference as the Supply Voltage................9
Outline Dimensions ....................................................................... 10
Ordering Guide .......................................................................... 11
REVISION HISTORY
7/04—Data Sheet Changed from Rev. C to Rev. D
Change to AD22100K Specifications............................................. 3
Updated Outline Dimensions ....................................................... 10
Changes to Ordering Guide .......................................................... 11
6/04—Data Sheet Changed from Rev. B to Rev. C
Changes to Format .............................................................Universal
Changes to Specifications................................................................ 3
Changes to Chip Specifications ...................................................... 3
Changes to Ratiometricity Considerations Section ..................... 8
Changes to Ordering Guide .......................................................... 10
Updated Outline Dimensions ....................................................... 10
12/94—Data Sheet Changed from Rev. A to Rev. B
AD22100
Rev. D | Page 3 of 12
SPECIFICATIONS
TA = 25°C and V+ = 4 V to 6.5 V, unless otherwise noted.
Table 1.
AD22100K AD22100A AD22100S
Parameter Min Typ Max Min Typ Max Min Typ Max Unit
TRANSFER FUNCTION VOUT = (V+/5 V) × [1.375 V +(22.5 mV/°C) × TA] V
TEMPERATURE COEFFICIENT (V+/5 V) × 22.5 mV/°C
TOTAL ERROR
Initial Error
TA = 25°C ±0.5 ±2.0 ±1.0 ±2.0 ±1.0 ±2.0 °C
Error Overtemperature
TA = TMIN ±0.75 ±2.0 ±2.0 ±3.7 ±3.0 ±4.0 °C
TA = TMAX ±0.75 ±2.0 ±2.0 ±3.0 ±3.0 ±4.0 °C
Nonlinearity
TA = TMAX to TMIN 0.5 0.5 1.0 % FS1
OUTPUT CHARACTERISTICS
Nominal Output Voltage
V+ = 5.0 V, TA = 0°C 1.375 V
V+ = 5.0 V, TA = +100°C 3.625 V
V+ = 5.0 V, TA = −40°C 0.475 V
V+ = 5.0 V, TA = +85°C 3.288 V
V+ = 5.0 V, TA = −50°C 0.250 V
V+ = 5.0 V, TA = +150°C 4.750 V
POWER SUPPLY
Operating Voltage 4.0 5.0 6.5 4.0 5.0 6.5 4.0 5.0 6.5 V
Quiescent Current 500 650 500 650 500 650 µA
TEMPERATURE RANGE
Guaranteed Temperature Range 0 +100 −40 +85 −50 +150 °C
Operating Temperature Range −50 +150 −50 +150 −50 +150 °C
PACKAGE TO-92 TO-92 TO-92
SOIC SOIC SOIC
1 FS (full scale) is defined as the operating temperature range −50°C to +150°C. The listed maximum specification limit applies to the guaranteed temperature range.
For example, the AD22100K has a nonlinearity of (0.5%) × (200°C) = 1°C over the guaranteed temperature range of 0°C to +100°C.
CHIP SPECIFICATIONS
TA = 25°C and V+ = 5.0 V, unless otherwise noted.
Table 2.
Paramater Min Typ Max Unit
TRANSFER FUNCTION VOUT = (V+/5 V) × [1.375 V +(22.5 mV/°C) × TA] V
TEMPERATURE COEFFICIENT (V+/5 V) × 22.5 mV/°C
OUTPUT CHARACTERISTICS
Error
TA = 25°C ±0.5 ±2.0 °C
Nominal Output Voltage
TA = 25°C 1.938 V
POWER SUPPLY
Operating Voltage 4.0 5.0 6.5 V
Quiescent Current 500 650 µA
TEMPERATURE RANGE
Guaranteed Temperature Range +25 °C
Operating Temperature Range −50 +150 °C
AD22100
Rev. D | Page 4 of 12
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Supply Voltage 10 V
Reversed Continuous Supply Voltage −10 V
Operating Temperature –50°C to +150°C
Storage Temperature –65°C to +160°C
Output Short Circuit to V+ or Ground Indefinite
Lead Temperature Range
(Soldering 10 sec)
300°C
Junction Temperature 150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and 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.
ESD 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 this product 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.
AD22100
Rev. D | Page 5 of 12
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
12 3GND
V
O
V+
BOTTOM VIEW
(Not to Scale)
00673-C-003
Figure 3. 3-Lead TO-92
Table 4. 3-Lead TO-92 Pin Function Descriptions
Pin No. Mnemonic Description
1 V+ Power Supply Input.
2 VODevice Output.
3 GND Ground Pin Must Be Connected to 0 V.
V+
1
V
O2
NC
3
GND
4
NC
8
NC
7
NC
6
NC
5
NC = NO CONNECT
AD22100
TOP VIEW
(Not to Scale)
00673-C-004
Figure 4. 8-Lead SOIC
Table 5. 8-Lead SOIC Pin Function Descriptions
Pin No. Mnemonic Description
1 V+ Power Supply Input.
2 VODevice Output.
3 NC No Connect.
4 GND Ground Pin Must Be Connected to 0 V.
5 NC No Connect.
6 NC No Connect.
7 NC No Connect.
8 NC No Connect.
AD22100
Rev. D | Page 6 of 12
TYPICAL PERFORMANCE CHARACTERISTICS
21200
4
0
8
6
10
12
14
800400
T (T0-92)
FLOW RATE (CFM)
T (SOIC)
16
τ
(Sec)
00673-C-005
Figure 5. Thermal Response vs. Flow Rate
50 12000
100
150
200
800400
FLOW RATE (CFM)
θ
JA
(°C/W)
(SOIC)
250
(T0-92)
00673-C-006
Figure 6. Thermal Resistance vs. Flow Rate
AD22100
Rev. D | Page 7 of 12
THEORY OF OPERATION
The AD22100 is a ratiometric temperature sensor IC whose
output voltage is proportional to its power supply voltage. The
heart of the sensor is a proprietary temperature-dependent
resistor, similar to an RTD, which is built into the IC. Figure 7
shows a functional block diagram of the AD22100.
V+
V
OUT
R
T
00673-C-001
Figure 7. Simplified Block Diagram
The temperature-dependent resistor, labeled RT, exhibits a
change in resistance that is nearly linearly proportional to
temperature. This resistor is excited with a current source that is
proportional to the power supply voltage. The resulting voltage
across RT is therefore both supply voltage proportional and line-
arly varying with temperature. The remainder of the AD22100
consists of an op amp signal conditioning block that takes the
voltage across RT and applies the proper gain and offset to
achieve the following output voltage function:
VOUT = (V+/5 V) × (1.375 V + 22.5 mV/°C × TA)
ABSOLUTE ACCURACY AND NONLINEARITY
SPECIFICATIONS
Figure 8 graphically depicts the guaranteed limits of accuracy
for the AD22100 and shows the performance of a typical part.
As the output is very linear, the major sources of error are off-
set, for instance error at room temperature, span error, and de-
viation from the theoretical 22.5 mV/°C. Demanding applica-
tions can achieve improved performance by calibrating these
offset and gain errors so that only the residual nonlinearity re-
mains as a significant source of error.
ERROR (°C)
TEMPERATURE (°C)
4
–4 150
–2
–3
–50
0
–1
1
2
3
100500
TYPICAL ERROR
MAXIMUM ERROR
OVER TEMPERATURE
MAXIMUM ERROR
OVER TEMPERATURE
00673-C-007
Figure 8. Typical AD22100 Performance
OUTPUT STAGE CONSIDERATIONS
As previously stated, the AD22100 is a voltage output device. A
basic understanding of the nature of its output stage is useful for
proper application. Note that at the nominal supply voltage of
5.0 V, the output voltage extends from 0.25 V at –50°C to +4.75
V at +150°C. Furthermore, the AD22100 output pin is capable
of withstanding an indefinite short circuit to either ground or
the power supply. These characteristics are provided by the out-
put stage structure shown in Figure 9.
V
+
V
OUT
00673-C-008
Figure 9. Output Stage Structure
The active portion of the output stage is a PNP transistor,
with its emitter connected to the V+ supply and its collector
connected to the output node. This PNP transistor sources the
required amount of output current. A limited pull-down capa-
bility is provided by a fixed current sink of about −80 µA, with
the term fixed referring to a current sink that is fairly insensitive
to either supply voltage or output loading conditions. The cur-
rent sink capability is a function of temperature, increasing its
pull-down capability at lower temperatures.
AD22100
Rev. D | Page 8 of 12
Due to its limited current sinking ability, the AD22100 is inca-
pable of driving loads to the V+ power supply and is instead
intended to drive grounded loads. A typical value for short-
circuit current limit is 7 mA, so devices can reliably source 1
mA or 2 mA. However, for best output voltage accuracy and
minimal internal self-heating, output current should be kept
below 1 mA. Loads connected to the V+ power supply should
be avoided as the current sinking capability of the AD22100 is
fairly limited. These considerations are typically not a problem
when driving a microcontroller analog-to-digital converter input
pin (see the Microprocessor A/D Interface Issues section).
RATIOMETRICITY CONSIDERATIONS
The AD22100 will operate with slightly better accuracy than
that listed in the data sheet specifications if the power supply is
held constant. This is because the AD22100’s output voltage
varies with both temperature and supply voltage, with some
errors. The ideal transfer function describing output voltage is:
(V+/5 V) × (1.375 V + 22.5 mV/°C × TA)
The ratiometricity error is defined as the percent change away
from the ideal transfer function as the power supply voltage
changes within the operating range of 4 V to 6.5 V. For the
AD22100, this error is typically less than 1%. A movement from
the ideal transfer function by 1% at 25°C, with a supply voltage
varying from 5.0 V to 5.50 V, results in a 1.94 mV change in
output voltage or 0.08°C error. This error term is greater at
higher temperatures because the output (and error term) is
directly proportional to temperature. At 150°C, the error in
output voltage is 4.75 mV or 0.19°C.
For example, with VS = 5.0 V, and TA = +25°C, the nominal
output of the AD22100 will be 1.9375 V. At VS = 5.50 V, the
nominal output will be 2.1313 V, an increase of 193.75 mV. A
proportionality error of 1% is applied to the 193.75 mV, yielding
an error term of 1.9375 mV. This error term translates to a
variation in output voltage of 2.1293 V to 2.3332 V. A 1.94 mV
error at the output is equivalent to about 0.08°C error in
accuracy.
If 150°C is substituted for 25°C in the above example, the error
term translates to a variation in output voltage of 5.2203 V to
5.2298 V. A 4.75 mV error at the output is equivalent to about
0.19°C error in accuracy.
MOUNTING CONSIDERATIONS
If the AD22100 is thermally attached and properly protected, it
can be used in any measuring situation where the maximum
range of temperatures encountered is between −50°C and
+150°C. Because plastic IC packaging technology is employed,
excessive mechanical stress must be avoided when fastening the
device with a clamp or screw-on heat tab. Thermally conductive
epoxy or glue is recommended for typical mounting conditions.
In wet or corrosive environments, an electrically isolated metal
or ceramic well should be used to shield the AD22100. Because
the part has a voltage output (as opposed to current), it offers
modest immunity to leakage errors, such as those caused by
condensation at low temperatures.
THERMAL ENVIRONMENT EFFECTS
The thermal environment in which the AD22100 is used
determines two performance traits: the effect of self-heating on
accuracy and the response time of the sensor to rapid changes
in temperature. In the first case, a rise in the IC junction
temperature above the ambient temperature is a function of two
variables: the power consumption of the AD22100 and the
thermal resistance between the chip and the ambient environ-
ment θJA. Self-heating error in °C can be derived by multiplying
the power dissipation by θJA. Because errors of this type can
vary widely for surroundings with different heat-sinking capaci-
ties, it is necessary to specify θJA under several conditions. Table
6 shows how the magnitude of self-heating error varies relative
to the environment. A typical part will dissipate about 2.2 mW
at room temperature with a 5 V supply and negligible output
loading. Table 6 indicates a θJA of 190°C/W in still air, without a
heat sink, yielding a temperature rise of 0.4°C. Thermal rise will
be considerably less in either moving air or with direct physical
connection to a solid (or liquid) body.
Table 6. Thermal Resistance (TO-92)
Medium θJA (°C/W) t (sec)1
Aluminum Block 60 2
Moving Air2
Without Heat Sink 75 3.5
Still Air
Without Heat Sink 190 15
AD22100
Rev. D | Page 9 of 12
Response of the AD22100 output to abrupt changes in ambient
temperature can be modeled by a single time constant t expo-
nential function. Figure 10 shows the typical response time
plots for a few media of interest.
% OF FINAL VALUES
100
0100
30
10
10
20
0
60
40
50
70
80
90
9080706050403020
STILL AIR
TIME (sec)
ALUMINUM
BLOCK
MOVING
AIR
00673-C-009
Figure 10. Response Time
The time constant t is dependent on θJA and the thermal capaci-
ties of the chip and the package. Table 6 lists the effective t (time
to reach 63.2% of the final value) for a few different media.
Copper printed circuit board connections were neglected in the
analysis; however, they will sink or conduct heat directly
through the AD22100’s solder plated copper leads. When faster
response is required, a thermally conductive grease or glue
between the AD22100 and the surface temperature being
measured should be used.
MICROPROCESSOR A/D INTERFACE ISSUES
The AD22100 is especially well suited to providing a low cost
temperature measurement capability for microprocessor/
microcontroller based systems. Many inexpensive 8-bit micro-
processors now offer an onboard 8-bit ADC capability at a
modest cost premium. Total cost of ownership then becomes a
function of the voltage reference and analog signal conditioning
necessary to mate the analog sensor with the microprocessor
ADC. The AD22100 can provide an ideal low cost system by
eliminating the need for a precision voltage reference and any
additional active components. The ratiometric nature of the
AD22100 allows the microprocessor to use the same power
supply as its ADC reference. Variations of hundreds of mil-
livolts in the supply voltage have little effect as both the
AD22100 and the ADC use the supply as their reference. The
nominal AD22100 signal range of 0.25 V to 4.75 V (−50°C to
+150°C) makes good use of the input range of a 0 V to 5 V
ADC. A single resistor and capacitor are recommended to pro-
vide immunity to the high speed charge dump glitches seen at
many microprocessor ADC inputs (see Figure 2).
An 8-bit ADC with a reference of 5 V will have a least signifi-
cant bit (LSB) size of 5 V/256 = 19.5 mV. This corresponds to a
nominal resolution of about 0.87°C.
USE WITH A PRECISION REFERENCE AS THE SUPPLY
VOLTAGE
While the ratiometric nature of the AD22100 allows for system
operation without a precision voltage reference, it can still be
used in such systems. Overall system requirements involving
other sensors or signal inputs may dictate the need for a fixed
precision ADC reference. The AD22100 can be converted to
absolute voltage operation by using a precision reference as the
supply voltage. For example, a 5.00 V reference can be used to
power the AD22100 directly. Supply current will typically be
500 µA, which is usually within the output capability of the
reference. Using a large number of AD22100s may require an
additional op amp buffer, as would scaling down a 10.00 V ref-
erence that might be found in instrumentation ADCs typically
operating from ±15 V supplies.
1 The time constant t is defined as the time to reach 63.2% of the final
temperature change.
2 1200 CFM.
AD22100
Rev. D | Page 10 of 12
OUTLINE DIMENSIONS
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS TO-226AA
0.115 (2.92)
0.080 (2.03)
0.115 (2.92)
0.080 (2.03)
0.165 (4.19)
0.125 (3.18)
1
2
3
BOTTOM VIEW
SQ
0.019 (0.482)
0.016 (0.407)
0.105 (2.66)
0.095 (2.42)
0.055 (1.40)
0.045 (1.15)
SEATING
PLANE
0.500 (12.70) MIN
0.205 (5.21)
0.175 (4.45)
0.210 (5.33)
0.170 (4.32)
0.135 (3.43)
MIN
0.050 (1.27)
MAX
Figure 11. 3-Pin Plastic Header Package [TO-92]
(T-3)
Dimensions shown in inches and millimeters
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099)× 45°
8°
0°
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
41
85
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2440)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARIT
Y
0.10
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MS-012AA
Figure 12. 8-Lead Standard Small Outline Package [SOIC]
(R-8)
Dimensions shown in inches and millimeters
AD22100
Rev. D | Page 11 of 12
ORDERING GUIDE
Models Temperature Range Package Description Package Outline
AD22100KT 0°C to +100°C 3-Pin Plastic Header Package (TO-92) T-3
AD22100KR 0°C to +100°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100KR-REEL7 0°C to +100°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100KRZ10°C to +100°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100KRZ-REEL71 0°C to +100°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100AT –40°C to +85°C 3-Pin Plastic Header Package (TO-92) T-3
AD22100AR –40°C to +85°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100AR-REEL –40°C to +85°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100AR-REEL7 –40°C to +85°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100ST –50°C to +150°C 3-Pin Plastic Header Package (TO-92) T-3
AD22100SR –50°C to +150°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100SR-REEL7 –50°C to +150°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100SRZ1 –50°C to +150°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100SRZ-REEL71 –50°C to +150°C 8-Lead Standard Small Outline Package (SOIC) R-8
AD22100KCHIPS DIE
1 Z = Pb-free part.
AD22100
Rev. D | Page 12 of 12
NOTES
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and regis-
tered trademarks are the property of their respective owners.
C00673–0–7/04(D)
