Two-Terminal IC
Temperature Transducer
AD590
Rev. C
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However, no responsibility is assumed by Analog Devices for its use, nor for any
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Specifications subject to change without notice. No license is granted by implication
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Tel: 781.329.4700 www.analog.com
Fax: 781.326.8703 © 2003 Analog Devices, Inc. All rights reserved.
FEATURES
Linear current output: 1 µA/K
Wide temperature range: −55°C to +150°C
Probe compatible ceramic sensor package
2-terminal device: voltage in/current out
Laser trimmed to ±0.5°C calibration accuracy (AD590M)
Excellent linearity: ±0.3°C over full range (AD590M)
Wide power supply range: 4 V to 30 V
Sensor isolation from case
Low cost
00533-C-001
–
+
TO-52 SOIC-8
NC = NO CONNECT
TOP VIEW
(Not to Scale)
NC
1
V+
2
V–
3
NC
4
NC
NC
NC
NC
8
7
6
5
FLATPAC
K
+–
Figure 1. Pin Designations
GENERAL DESCRIPTION
The AD590 is a 2-terminal integrated circuit temperature
transducer that produces an output current proportional to
absolute temperature. For supply voltages between 4 V and 30 V
the device acts as a high-impedance, constant current regulator
passing 1 µA/K. Laser trimming of the chip’s thin-film resistors
is used to calibrate the device to 298.2 µA output at 298.2 K
(25°C).
The AD590 should be used in any temperature-sensing
application below 150°C in which conventional electrical
temperature sensors are currently employed. The inherent low
cost of a monolithic integrated circuit combined with the
elimination of support circuitry makes the AD590 an attractive
alternative for many temperature measurement situations.
Linearization circuitry, precision voltage amplifiers, resistance
measuring circuitry, and cold junction compensation are not
needed in applying the AD590.
In addition to temperature measurement, applications include
temperature compensation or correction of discrete
components, biasing proportional to absolute temperature, flow
rate measurement, level detection of fluids and anemometry.
The AD590 is available in chip form, making it suitable for
hybrid circuits and fast temperature measurements in protected
environments.
The AD590 is particularly useful in remote sensing applications.
The device is insensitive to voltage drops over long lines due to
its high impedance current output. Any well-insulated twisted
pair is sufficient for operation at hundreds of feet from the
receiving circuitry. The output characteristics also make the
AD590 easy to multiplex: the current can be switched by a
CMOS multiplexer or the supply voltage can be switched by a
logic gate output.
PRODUCT HIGHLIGHTS
1. The AD590 is a calibrated, 2-terminal temperature sensor
requiring only a dc voltage supply (4 V to 30 V). Costly
transmitters, filters, lead wire compensation, and
linearization circuits are all unnecessary in applying the
device.
2. State-of-the-art laser trimming at the wafer level in
conjunction with extensive final testing ensures that
AD590 units are easily interchangeable.
3. Superior interface rejection occurs, because the output is a
current rather than a voltage. In addition, power
requirements are low (1.5 mWs @ 5 V @ 25°C). These
features make the AD590 easy to apply as a remote sensor.
4. The high output impedance (>10 MΩ) provides excellent
rejection of supply voltage drift and ripple. For instance,
changing the power supply from 5 V to 10 V results in only
a 1 µA maximum current change, or 1°C equivalent error.
5. The AD590 is electrically durable: it withstands a forward
voltage of up to 44 V and a reverse voltage of 20 V.
Therefore, supply irregularities or pin reversal does not
damage the device.
AD590
Rev. C | Page 2 of 16
TABLE OF CONTENTS
Specifications..................................................................................... 3
AD590J and AD590K Specifications ......................................... 3
AD590L and AD590M Specifications........................................ 4
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Product Description......................................................................... 6
Circuit Description....................................................................... 6
Explanation of Temperature Sensor Specifications ................. 6
Calibration Error .......................................................................... 7
Error Versus Temperature: with Calibration Error Trimmed
Out...................................................................................................7
Error Versus Temperature: No User Trims ................................7
Nonlinearity ...................................................................................7
Voltage and Thermal Environment Effects ...............................8
General Applications...................................................................... 10
Outline Dimensions....................................................................... 13
Ordering Guide .......................................................................... 14
REVISION HISTORY
Revision C
9/03—Data Sheet Changed from REV. B to REV. C.
Added SOIC-8 package…………………………Universal
Change to Figure 1…………………………………….…1
Updated OUTLINE DIMENSIONS…………...……….13
Added ORDERING GUIDE………………...………….14
AD590
Rev. C | Page 3 of 16
SPECIFICATIONS
AD590J AND AD590K SPECIFICATIONS
Table 1. @ 25°C and VS = 5 V unless otherwise noted
AD590J AD590K
Parameter Min Typ Max Min Typ Max Unit
POWER SUPPLY
Operating Voltage Range 4 30
4 30 Volts
OUTPUT
Nominal Current Output @ 25°C (298.2K) 298.2 298.2 µA
Nominal Temperature Coefficient 1 1 µA/K
Calibration Error @ 25°C ±5.0 ±2.5 °C
Absolute Error (over rated performance temperature range)
Without External Calibration Adjustment ±10 ±5.5 °C
With 25°C Calibration Error Set to Zero ±3.0 ±2.0 °C
Nonlinearity
For TO-52 and Flatpack packages ±1.5 ±0.8 °C
For 8-Lead SOIC package ±1.5 ±1.0 °C
Repeatability1 ±0.1 ±0.1 °C
Long-Term Drift2 ±0.1 ±0.1 °C
Current Noise 40 40 pA/√Hz
Power Supply Rejection
4 V ≤ VS ≤ 5 V 0.5 0.5 µA/V
5 V ≤ VS ≤ 15 V 0.2 0.2 µV/V
15 V ≤ VS ≤ 30 V 0.1 0.1 µA/V
Case Isolation to Either Lead 1010 10
10 Ω
Effective Shunt Capacitance 100 100 pF
Electrical Turn-On Time 20 20 µs
Reverse Bias Leakage Current3
(Reverse Voltage = 10 V) 10 10 pA
1 Maximum deviation between +25°C readings after temperature cycling between –55°C and +150°C; guaranteed, not tested.
2 Conditions: constant 5 V, constant 125°C; guaranteed, not tested.
3 Leakage current doubles every 10°C.
Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min
and max specifications are guaranteed, although only those shown in boldface are tested on all production units.
AD590
Rev. C | Page 4 of 16
AD590L AND AD590M SPECIFICATIONS
Table 2. @ 25°C and VS = 5 V unless otherwise noted
AD590L AD590M
Parameter Min Typ Max Min Typ Max Unit
POWER SUPPLY
Operating Voltage Range 4 30 4 30 Volts
OUTPUT
Nominal Current Output @ 25°C (298.2K) 298.2 298.2 µA
Nominal Temperature Coefficient 1 1 µA/K
Calibration Error @ +25°C ±1.0 ±0.5 °C
Absolute Error (over rated performance temperature range) °C
Without External Calibration Adjustment ±3.0 ±1.7 °C
With ± 25°C Calibration Error Set to Zero ±1.6 ±1.0 °C
Nonlinearity ±0.4 ±0.3 °C
Repeatability1 ±0.1
±0.1 °C
Long-Term Drift2 ±0.1
±0.1 °C
Current Noise 40 40 pA/√Hz
Power Supply Rejection
4 V ≤ VS ≤ 5 V 0.5 0.5 µA/V
5 V ≤ VS ≤ 15 V 0.2 0.2 µA/V
15 V ≤ VS ≤ 30 V 0.1 0.1 µA/V
Case Isolation to Either Lead 1010 1010 Ω
Effective Shunt Capacitance 100 100 pF
Electrical Turn-On Time 20
20 µs
Reverse Bias Leakage Current3
(Reverse Voltage = 10 V) 10 10 pA
1 Maximum deviation between +25°C readings after temperature cycling between –55°C and +150°C; guaranteed, not tested.
2 Conditions: constant 5 V, constant 125°C; guaranteed, not tested.
3 Leakage current doubles every 10°C.
Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min
and max specifications are guaranteed, although only those shown in boldface are tested on all production units.
00533-C-002
+223°
–50° +273°
0° +298°
+25° +323°
+50° +373°
+100° +423°
+150°
–100° 0° +100° +200° +300°
+32° +70° +212°
°K
°C
°F
(
)
()
7.45932
5
9
15.27332
9
5
+=+=
+=−=
FRCF
CKFC
oooo
ooo
Figure 2. Temperature Scale Conversion Equations
AD590
Rev. C | Page 5 of 16
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Forward Voltage ( E+ or E–) 44 V
Reverse Voltage (E+ to E–) −20 V
Breakdown Voltage (Case E+ or E–) ±200 V
Rated Performance Temperature Range1−55°C to +150°C
Storage Temperature Range1−65°C to +155°C
Lead Temperature (Soldering, 10 sec) 300°C
1The AD590 has been used at –100°C and +200°C for short periods of
measurement with no physical damage to the device. However, the absolute
errors specified apply to only the rated performance temperature range.
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.
AD590
Rev. C | Page 6 of 16
PRODUCT DESCRIPTION
The AD590H has 60 µ inches of gold plating on its Kovar leads
and Kovar header. A resistance welder is used to seal the nickel
cap to the header. The AD590 chip is eutectically mounted to
the header and ultrasonically bonded to with 1 mil aluminum
wire. Kovar composition: 53% iron nominal; 29% ±1% nickel;
17% ±1% cobalt; 0.65% manganese max; 0.20% silicon max;
0.10% aluminum max; 0.10% magnesium max; 0.10%
zirconium max; 0.10% titanium max; 0.06% carbon max.
The AD590F is a ceramic package with gold plating on its Kovar
leads, Kovar lid, and chip cavity. Solder of 80/20 Au/Sn
composition is used for the 1.5 mil thick solder ring under the
lid. The chip cavity has a nickel underlay between the
metallization and the gold plating. The AD590 chip is
eutectically mounted in the chip cavity at 410°C and
ultrasonically bonded to with 1 mil aluminum wire. Note that
the chip is in direct contact with the ceramic base, not the metal
lid. When using the AD590 in die form, the chip substrate must
be kept electrically isolated (floating) for correct circuit
operation.
THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM;
CONSULT THE CHIP CATALOG FOR DETAILS
V+
V–
42MILS
66MILS
00533-C-003
Figure 3. Metalization Diagram
CIRCUIT DESCRIPTION1
The AD590 uses a fundamental property of the silicon
transistors from which it is made to realize its temperature
proportional characteristic: if two identical transistors are
operated at a constant ratio of collector current densities, r, then
the difference in their base-emitter voltage will be (kT/q)(In r).
Since both k (Boltzman’s constant) and q (the charge of an
electron) are constant, the resulting voltage is directly
proportional to absolute temperature (PTAT).
In the AD590, this PTAT voltage is converted to a PTAT current
by low temperature coefficient thin-film resistors. The total
current of the device is then forced to be a multiple of this
1 For a more detailed description, see M.P. Timko, “A Two-Terminal IC
Temperature Transducer,” IEEE J. Solid State Circuits, Vol. SC-11, p. 784-788,
Dec. 1976. Understanding the Specifications–AD590.
PTAT current. Figure 4 is the schematic diagram of the AD590.
In this figure, Q8 and Q11 are the transistors that produce the
PTAT voltage. R5 and R6 convert the voltage to current. Q10,
whose collector current tracks the collector currents in Q9 and
Q11, supplies all the bias and substrate leakage current for the
rest of the circuit, forcing the total current to be PTAT. R5 and
R6 are laser-trimmed on the wafer to calibrate the device at
25°C.
Figure 5 shows the typical V–I characteristic of the circuit at
25°C and the temperature extremes.
00533-C-004
Q
1
Q
2
R
2
1040Ω
Q
5
Q
3
Q
4
C
1
26pF
Q
6
Q
7
Q
12
R
4
11kΩ
Q
8
Q
10
Q
9
CHIP
SUBSTRATE
Q
11
118 R
5
146Ω
R
6
820Ω
R
1
260Ω
+
–
R
3
5kΩ
Figure 4. Schematic Diagram
00533-C-005
012
+150°C
423
298
218
+25°C
I
OUT
(µA)
–55°C
34
SUPPLY VOLTAGE (V)
56 30
Figure 5. V-1 Plot
EXPLANATION OF TEMPERATURE SENSOR
SPECIFICATIONS
The way in which the AD590 is specified makes it easy to apply
in a wide variety of applications. It is important to understand
the meaning of the various specifications and the effects of
supply voltage and thermal environment on accuracy.
AD590
Rev. C | Page 7 of 16
The AD590 is basically a PTAT (proportional to absolute
temperature)1 current regulator. That is, the output current is
equal to a scale factor times the temperature of the sensor in
degrees Kelvin. This scale factor is trimmed to 1 µA/K at the
factory, by adjusting the indicated temperature (that is, the
output current) to agree with the actual temperature. This is
done with 5 V across the device at a temperature within a few
degrees of 25°C (298.2K). The device is then packaged and
tested for accuracy over temperature.
CALIBRATION ERROR
At final factory test, the difference between the indicated
temperature and the actual temperature is called the calibration
error. Since this is a scale factory error, its contribution to the
total error of the device is PTAT. For example, the effect of the
1°C specified maximum error of the AD590L varies from
0.73°C at –55°C to 1.42°C at 150°C. Figure 6 shows how an
exaggerated calibration error would vary from the ideal over
temperature.
00533-C-006
I
ACTUAL
298.2
I
OUT
(µA)
298.2
TEMPERATURE (°K)
ACTUAL
TRANSFER
FUNCTION
IDEAL
TRANSFER
FUNCTION
CALIBRATION
ERROR
Figure 6. Calibration Error vs. Temperature
The calibration error is a primary contributor to maximum
total error in all AD590 grades. However, since it is a scale factor
error, it is particularly easy to trim. Figure 7 shows the most
elementary way of accomplishing this. To trim this circuit, the
temperature of the AD590 is measured by a reference
temperature sensor and R is trimmed so that VT = 1 mV/K at
that temperature. Note that when this error is trimmed out at
one temperature, its effect is zero over the entire temperature
range. In most applications there is a current-to-voltage
conversion resistor (or, as with a current input ADC, a
reference) that can be trimmed for scale factor adjustment.
1 T(°C) = T(K) –273.2. Zero on the Kelvin scale is “absolute zero”; there is no
lower temperature.
00533-C-007
5V
R
100ΩV
T
= 1mV/K
AD590
950Ω
+
–
+
–
+
–
Figure 7. One Temperature Trim
ERROR VERSUS TEMPERATURE: WITH
CALIBRATION ERROR TRIMMED OUT
Each AD590 is tested for error over the temperature range with
the calibration error trimmed out. This specification could also
be called the “variance from PTAT,” because it is the maximum
difference between the actual current over temperature and a
PTAT multiplication of the actual current at 25°C. This error
consists of a slope error and some curvature, mostly at the
temperature extremes. Figure 8 shows a typical AD590K
temperature curve before and after calibration error trimming.
AFTER
CALIBRATION
TRIM
00533-C-008
ABSOLUTE ERROR (°C)
2
0
–2 –55 150
TEMPERATURE (°C)
CALIBRATION
ERROR
BEFORE
CALIBRATION
TRIM
Figure 8. Effect to Scale Factor Trim on Accuracy
ERROR VERSUS TEMPERATURE: NO USER TRIMS
Using the AD590 by simply measuring the current, the total
error is the variance from PTAT, described above, plus the effect
of the calibration error over temperature. For example, the
AD590L maximum total error varies from 2.33°C at –55°C to
3.02°C at 150°C. For simplicity, only the large figure is shown on
the specification page.
NONLINEARITY
Nonlinearity as it applies to the AD590 is the maximum
deviation of current over temperature from a best-fit straight
line. The nonlinearity of the AD590 over the −55°C to +150°C
range is superior to all conventional electrical temperature
sensors such as thermocouples, RTDs, and thermistors. Figure 9
shows the nonlinearity of the typical AD590K from Figure 8.
AD590
Rev. C | Page 8 of 16
0.8°C
MAX
0.8°C MAX
00533-C-009
ABSOLUTE ERROR (°C)
1.6
–1.6
–0.8
0
0.8
–55 150
TEMPERATURE (°C)
0.8°C
MAX
Figure 9. Nonlinearity
Figure 10 shows a circuit in which the nonlinearity is the major
contributor to error over temperature. The circuit is trimmed by
adjusting R1 for a 0 V output with the AD590 at 0°C. R2 is then
adjusted for 10 V out with the sensor at 100°C. Other pairs of
temperatures may be used with this procedure as long as they
are measured accurately by a reference sensor. Note that for
15 V output (150°C) the V+ of the op amp must be greater than
17 V. Also note that V− should be at least −4 V; if V− is ground,
there is no voltage applied across the device.
00533-C-010
30pF
AD707A 100mV/°C
V
T
= 100mV/°C
AD590
A
D581
V–
35.7kΩ
R
1
2kΩ97.6kΩ
R
2
5kΩ
27kΩ
15V
Figure 10. 2-Temperature Trim
00533-C-011
TEMPERATURE (°C)
2
–2
0
–55 0 150100
TEMPERATURE (°C)
Figure 11. Typical 2-Trim Accuracy
VOLTAGE AND THERMAL ENVIRONMENT EFFECTS
The power supply rejection specifications show the maximum
expected change in output current versus input voltage changes.
The insensitivity of the output to input voltage allows the use of
unregulated supplies. It also means that hundreds of ohms of
resistance (such as a CMOS multiplexer) can be tolerated in
series with the device.
It is important to note that using a supply voltage other than 5 V
does not change the PTAT nature of the AD590. In other words,
this change is equivalent to a calibration error and can be
removed by the scale factor trim (see Figure 8).
The AD590 specifications are guaranteed for use in a low
thermal resistance environment with 5 V across the sensor.
Large changes in the thermal resistance of the sensor’s
environment change the amount of self-heating and result in
changes in the output, which are predictable but not necessarily
desirable.
The thermal environment in which the AD590 is used
determines two important characteristics: the effect of self-
heating and the response of the sensor with time. Figure 12 is a
model of the AD590 that demonstrates these characteristics.
00533-C-012
θ
JC
θ
CA
T
J
PC
CH
C
C
T
A
+
–
T
C
Figure 12. Thermal Circuit Model
As an example, for the TO-52 package, θJC is the thermal
resistance between the chip and the case, about 26°C/W. θCA is
the thermal resistance between the case and the surroundings
and is determined by the characteristics of the thermal
connection. Power source P represents the power dissipated on
the chip. The rise of the junction temperature, TJ, above the
ambient temperature TA is
(
)
CAJCA
JPTT θ+θ
=
−
Equation 1.
Table 4 gives the sum of θJC and θCA for several common
thermal media for both the H and F packages. The heat sink
used was a common clip-on. Using Equation 1, the temperature
rise of an AD590 H package in a stirred bath at 25°C, when
driven with a 5 V supply, is 0.06°C. However, for the same
conditions in still air, the temperature rise is 0.72°C. For a given
supply voltage, the temperature rise varies with the current and
is PTAT. Therefore, if an application circuit is trimmed with the
sensor in the same thermal environment in which it will be
used, the scale factor trim compensates for this effect over the
entire temperature range.
AD590
Rev. C | Page 9 of 16
Table 4. Thermal Resistance
θ
JC + θCA (°C/Watt) τ (sec)1
Medium H F H F
Aluminum Block 30 10 0.6 0.1
Stirred Oil242 60 1.4 0.6
Moving Air3
With Heat Sink 45 – 5.0 –
Without Heat Sink 115 190 13.5 10.0
Still Air
With Heat Sink 191 – 108 –
Without Heat Sink 480 650 60 30
1τ is dependent upon velocity of oil; average of several velocities listed above.
2Air velocity @ 9 ft/sec.
3The time constant is defined as the time required to reach 63.2% of an
instantaneous temperature change.
The time response of the AD590 to a step change in
temperature is determined by the thermal resistances and the
thermal capacities of the chip, CCH, and the case, CC. CCH is
about 0.04 Ws/°C for the AD590. CC varies with the measured
medium, because it includes anything that is in direct thermal
contact with the case. The single time constant exponential
curve of Figure 13 is usually sufficient to describe the time
response, T (t). Tabl e 4 shows the effective time constant, τ, for
several media.
00533-C-013
SENSED TEMPERATURE
T
FINAL
T
INITIAL
τ4τ
TIME
T(t) = T
INITIAL
+ (T
FINAL
– T
INITIAL
)× (1 – e
–t/τ
)
Figure 13. Time Response Curve
AD590
Rev. C | Page 10 of 16
GENERAL APPLICATIONS
Figure 14 demonstrates the use of a low cost digital panel meter
for the display of temperature on either the Kelvin, Celsius, or
Fahrenheit scales. For Kelvin temperature, Pins 9, 4, and 2 are
grounded; for Fahrenheit temperature, Pins 4 and 2 are left
open.
00533-C-014
6
5
9
4
2
OFFSET
CALIBRATION
5V
GAIN
SCALING
OFFSET
SCALING
3
8
AD2040
GND
A
D590
+
–
Figure 14. Variable Scale Display
The above configuration yields a 3-digit display with 1°C or 1°F
resolution, in addition to an absolute accuracy of ±2.0°C over
the −55°C to +125°C temperature range, if a one-temperature
calibration is performed on an AD590K, AD590L, or AD590M.
Connecting several AD590 units in series as shown in Figure 15
allows the minimum of all the sensed temperatures to be
indicated. In contrast, using the sensors in parallel yields the
average of the sensed temperatures.
00533-C-015
AD590
+
–
AD590
+
–
AD590
+
–+
VT MIN
10kΩ
(
0.1%) –
+
–
AD590
+
–
+
–
+
VT AVG
333.3Ω
(0.1%) –
5V
15V
Figure 15. Series and Parallel Connection
The circuit in Figure 16 demonstrates one method by which
differential temperature measurements can be made. R1 and R2
can be used to trim the output of the op amp to indicate a
desired temperature difference. For example, the inherent offset
between the two devices can be trimmed in. If V+ and V− are
radically different, then the difference in internal dissipation
causes a differential internal temperature rise. This effect can be
used to measure the ambient thermal resistance seen by the
sensors in applications such as fluid-level detectors or
anemometry.
00533-C-016
AD590L
#2
+
–
AD590L
#1
+
–R4
10kΩ
R3
10kΩ
R1
5MΩ
R2
50kΩ
V+
(T1 – T2) ×(10mV/°C)
V–
AD707A
–
+
Figure 16. Differential Measurements
Figure 17 is an example of a cold junction compensation circuit
for a Type J thermocouple using the AD590 to monitor the
reference junction temperature. This circuit replaces an ice-bath
as the thermocouple reference for ambient temperatures
between 15°C and 35°C. The circuit is calibrated by adjusting RT
for a proper meter reading with the measuring junction at a
known reference temperature and the circuit near 25°C. Using
components with the TCs as specified in Figure 17,
compensation accuracy is within ±0.5°C for circuit
temperatures between 15°C and 35°C. Other thermocouple
types can be accommodated with different resistor values. Note
that the TCs of the voltage reference and the resistors are the
primary contributors to error.
00533-C-017
+
–
REFERENCE
JUNCTION IRON
+
–
7.5V
AD590
AD580
CONSTANTAN
MEASURING
JUNCTION
RESISTORS ARE 1%, 50PPM/°C
METER
+–
–
+CU
52.3Ω
8.66kΩ
VOUT
RT
1kΩ
Figure 17. Cold Junction Compensation Circuit for Type J Thermocouple
Figure 18 is an example of a current transmitter designed to be
used with 40 V, 1 kΩ systems; it uses its full current range of
4 mA to 20 mA for a narrow span of measured temperatures. In
this example, the 1 µA/K output of the AD590 is amplified to
1 mA/°C and offset so that 4 mA is equivalent to 17°C and
20 mA is equivalent to 33°C. RT is trimmed for proper reading
at an intermediate reference temperature. With a suitable choice
of resistors, any temperature range within the operating limits
of the AD590 may be chosen.
AD590
Rev. C | Page 11 of 16
00533-C-018
30pF
V+
4mA = 17°C
12mA = 25°C
20mA = 33°C –
+
–
+
AD581
V
OUT
R
T
5kΩ
10Ω
10kΩ
12.7kΩ
35.7kΩ
5kΩ500Ω
AD590
AD707A
–
+
0.01µF
V–
Figure 18. 4 mA to 20 mA Current Transmitter
Figure 19 is an example of a variable temperature control circuit
(thermostat) using the AD590. RH and RL are selected to set the
high and low limits for RSET. RSET could be a simple pot, a
calibrated multiturn pot, or a switched resistive divider.
Powering the AD590 from the 10 V reference isolates the
AD590 from supply variations while maintaining a reasonable
voltage (~7 V) across it. Capacitor C1 is often needed to filter
extraneous noise from remote sensors. RB is determined by the
β of the power transistor and the current requirements of the
load.
00533-C-019
LM311
–
+
C
1
2
341
7
10kΩ
R
SET
R
L
R
B
R
H
V–
V+
V+
AD590
–
+
AD581
OUT HEATING
ELEMENTS
GND
10V
Figure 19. Simple Temperature Control Circuit
Figure 20 shows that the AD590 can be configured with an 8-bit
DAC to produce a digitally controlled set point. This particular
circuit operates from 0°C (all inputs high) to 51.0°C (all inputs
low) in 0.2°C steps. The comparator is shown with 1.0°C
hysteresis, which is usually necessary to guard-band for
extraneous noise. Omitting the 5.1 MΩ resistor results in no
hysteresis.
00533-C-020
MC
1408/1508
DAC OUT
–15V
+5V
REF
OUTPUT HIGH-
TEMPERATURE ABOVE SET POINT
OUTPUT LOW-
TEMPERATURE BELOW SET POINT
1.25kΩ
+5V
+2.5V
AD580
20pF
BIT 1 BIT 8
BIT 2 BIT 7
BIT 3 BIT 6
BIT 4 BIT 5
1.15kΩ
200Ω
200Ω, 15T
6.98kΩ
1kΩ, 15T
–15V
AD590
–
+
–15V
+5V +5V
1
4
2
387
LM311
1kΩ
5.1MΩ
6.8kΩ
Figure 20. DAC Set Point
The voltage compliance and the reverse blocking characteristic
of the AD590 allows it to be powered directly from 5 V CMOS
logic. This permits easy multiplexing, switching, or pulsing for
minimum internal heat dissipation. In Figure 21, any AD590
connected to a logic high passes a signal current through the
current measuring circuitry, while those connected to a logic
zero pass insignificant current. The outputs used to drive the
AD590s may be employed for other purposes, but the additional
capacitance due to the AD590 should be taken into account.
00533-C-021
5V
CMOS
GATES
AD590
1kΩ (0.1%)
–
+–
+–
+–
+
Figure 21. AD590 Driven from CMOS Logic
CMOS analog multiplexers can also be used to switch AD590
current. Due to the AD590’s current mode, the resistance of
such switches is unimportant as long as 4 V is maintained
across the transducer. Figure 22 shows a circuit that combines
the principle demonstrated in Figure 21 with an 8-channel
CMOS multiplexer. The resulting circuit can select 1–80 sensors
over only 18 wires with a 7-bit binary word.
AD590
Rev. C | Page 12 of 16
The inhibit input on the multiplexer turns all sensors off for
minimum dissipation while idling.
Figure 23 demonstrates a method of multiplexing the AD590 in
the two-trim mode (see Figure 10 and Figure 11). Additional
AD590s and their associated resistors can be added to multiplex
up to eight channels of ±0.5°C absolute accuracy over the
temperature range of −55°C to +125°C. The high temperature
restriction of 125°C is due to the output range of the op amps;
output to 150°C can be achieved by using a 20 V supply for the
op amp.
00533-C-022
4028
CMOS
BCD-TO-
DECIMAL
DECODER
11
9
10
11
6
16
10V
3
14
2
AD590
1
0
2
10kΩ 10mV/°C
4051 CMOS ANALOG
MULTIPLEXER
–
+
22–
+
12–
+
02
–
+
21–
+
11–
+
01
–
+
20–
+
10–
+
00
8
12
ROW
SELECT
COLUMN
SELECT
INHIBIT
78
13
10
0
13
1
14
2
15
BINARY TO 1-OF-8 DECODER
LOGIC
LEVEL
INTERFACE
10V
16
Figure 22. Matrix Multiplexer
00533-C-023
–
+
AD590L
–
+
AD590L
DECODER/
DRIVER
S1
S2
S8
AD7501
–15V
2kΩ
35.7kΩ5k
Ω
97.6kΩ
2kΩ
35.7kΩ5kΩ97.6kΩ
+15V TTL/DTL TO CMOS
INTERFACE
BINARY
CHANNEL
SELECT
EN
–15V
27kΩ
10mV/°C
V+
AD707A
+15V
AD581
V
OUT
–
+
–5V TO –15V
Figure 23. 8-Channel Multiplexer
AD590
Rev. C | Page 13 of 16
OUTLINE DIMENSIONS
0.0065 (0.17)
0.0050 (0.13)
0.0045 (0.12)
0.050 (1.27)
0.041 (1.04)
POSITIVE LEAD
INDICATOR
0.500 (12.69)
MIN 0.230 (5.84)
0.250 (6.35)
0.093 (2.36)
0.081 (2.06)
0.055 (1.40)
0.050 (1.27)
0.045 (1.14)
0.019 (0.48)
0.017 (0.43)
0.015 (0.38)
Figure 24. 2-Lead Ceramic Flat Package [CQFP]
(F-2)
Dimensions shown in inches and (millimeters)
0.250 (6.35)
MIN
0.150 (3.81)
0.115 (2.92)
0.050
(1.27)
MAX
0.019 (0.48)
0.016 (0.41)
0.021 (0.53)
MAX
0.030 (0.76)
MAX
0.195 (4.95)
0.178 (4.52)
0.230 (5.84)
0.209 (5.31)
0.500
(12.70)
MIN
0.046 (1.17)
0.036 (0.91)
0.048 (1.22)
0.028 (0.71)
0.050 (1.27) T.P.
3
1
0.100
(2.54)
T.P.
0.050
(1.27)
T.P. 45 T.P.
2
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETERS DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
Figure 25. 3-Pin Metal Header Package [TO-52]
(H-03)
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 26. 8-Lead Standard Small Outline Package [SOIC]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
AD590
Rev. C | Page 14 of 16
ORDERING GUIDE
Model Temperature Range Package Description Package Option
AD590JH1−55°C to +150°C TO-52 H-03A
AD590JF1−55°C to +150°C Flatpack F-2A
AD590JR −55°C to +150°C 8-Lead SOIC SOIC-8
AD590KH1−55°C to +150°C TO-52 H-03A
AD590KF1−55°C to +150°C Flatpack F-2A
AD590KR −55°C to +150°C 8-Lead SOIC SOIC-8
AD590LH1−55°C to +150°C TO-52 H-03A
AD590LF1 −55°C to +150°C Flatpack F-2A
AD590MH1−55°C to +150°C TO-52 H-03A
AD590MF1−55°C to +150°C Flatpack F-2A
AD590JR-REEL −55°C to +150°C 8-Lead SOIC SOIC-8
AD590KR-REEL −55°C to +150°C 8-Lead SOIC SOIC-8
AD590JCHIPS −55°C to +150°C TO-52 H-03A
1Available in 883B; consult factory for data sheet.
AD590
Rev. C | Page 15 of 16
NOTES
AD590
Rev. C | Page 16 of 16
NOTES
© 2003 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
C00533–0–9/03(C)
