Two-Terminal IC

Temperature Transducer
AD590
FLATPACK TO-52 SOIC-8
FEATURES –
NC 1 8 NC
Linear current output: 1 µA/K V+ 2 TOP VIEW 7 NC

Wide temperature range: −55°C to +150°C V– 3 (Not to Scale) 6 NC

+
Probe compatible ceramic sensor package NC 4 5 NC

2-terminal device: voltage in/current out NC = NO CONNECT

Laser trimmed to ±0.5°C calibration accuracy (AD590M)
Excellent linearity: ±0.3°C over full range (AD590M)

00533-C-001
Wide power supply range: 4 V to 30 V
+ –
Sensor isolation from case
Low cost Figure 1. Pin Designations

GENERAL DESCRIPTION
The AD590 is a 2-terminal integrated circuit temperature receiving circuitry. The output characteristics also make the
transducer that produces an output current proportional to AD590 easy to multiplex: the current can be switched by a
absolute temperature. For supply voltages between 4 V and 30 V CMOS multiplexer or the supply voltage can be switched by a
the device acts as a high-impedance, constant current regulator logic gate output.
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 PRODUCT HIGHLIGHTS
(25°C). 1. The AD590 is a calibrated, 2-terminal temperature sensor
requiring only a dc voltage supply (4 V to 30 V). Costly
The AD590 should be used in any temperature-sensing
transmitters, filters, lead wire compensation, and
application below 150°C in which conventional electrical
linearization circuits are all unnecessary in applying the
temperature sensors are currently employed. The inherent low
device.
cost of a monolithic integrated circuit combined with the
elimination of support circuitry makes the AD590 an attractive 2. State-of-the-art laser trimming at the wafer level in
alternative for many temperature measurement situations. conjunction with extensive final testing ensures that
Linearization circuitry, precision voltage amplifiers, resistance AD590 units are easily interchangeable.
measuring circuitry, and cold junction compensation are not
needed in applying the AD590. 3. Superior interface rejection occurs, because the output is a
current rather than a voltage. In addition, power
In addition to temperature measurement, applications include requirements are low (1.5 mWs @ 5 V @ 25°C). These
temperature compensation or correction of discrete features make the AD590 easy to apply as a remote sensor.
components, biasing proportional to absolute temperature, flow
rate measurement, level detection of fluids and anemometry. 4. The high output impedance (>10 MΩ) provides excellent
The AD590 is available in chip form, making it suitable for rejection of supply voltage drift and ripple. For instance,
hybrid circuits and fast temperature measurements in protected changing the power supply from 5 V to 10 V results in only
environments. a 1 µA maximum current change, or 1°C equivalent error.

The AD590 is particularly useful in remote sensing applications. 5. The AD590 is electrically durable: it withstands a forward
The device is insensitive to voltage drops over long lines due to voltage of up to 44 V and a reverse voltage of 20 V.
its high impedance current output. Any well-insulated twisted Therefore, supply irregularities or pin reversal does not
pair is sufficient for operation at hundreds of feet from the damage the device.

Rev. C
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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
or otherwise under any patent or patent rights of Analog Devices. Trademarks and Tel: 781.329.4700 www.analog.com
registered trademarks are the property of their respective owners. Fax: 781.326.8703 © 2003 Analog Devices, Inc. All rights reserved.
AD590

TABLE OF CONTENTS
Specifications..................................................................................... 3 Error Versus Temperature: with Calibration Error Trimmed
Out...................................................................................................7
AD590J and AD590K Specifications ......................................... 3
Error Versus Temperature: No User Trims ................................7
AD590L and AD590M Specifications........................................ 4
Nonlinearity ...................................................................................7
Absolute Maximum Ratings............................................................ 5
Voltage and Thermal Environment Effects ...............................8
ESD Caution.................................................................................. 5
General Applications...................................................................... 10
Product Description......................................................................... 6
Outline Dimensions ....................................................................... 13
Circuit Description....................................................................... 6
Ordering Guide .......................................................................... 14
Explanation of Temperature Sensor Specifications ................. 6

Calibration Error .......................................................................... 7

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

Rev. C | Page 2 of 16
 AD590

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 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.

Rev. C | Page 3 of 16
AD590
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.

°K +223° +273° +298° +323° +373° +423°

°C –50° 0° +25° +50° +100° +150°
00533-C-002

°F –100° 0° +100° +200° +300°

+32° +70° +212°

o
C= ( F − 32) K = oC + 273.15
5 o
9
F = (oC + 32 ) oR = oF + 459.7
o 9
5
Figure 2. Temperature Scale Conversion Equations

Rev. C | Page 4 of 16
 AD590

ABSOLUTE MAXIMUM RATINGS

Table 3.
Parameter Rating Stresses above those listed under Absolute Maximum Ratings
Forward Voltage ( E+ or E–) 44 V may cause permanent damage to the device. This is a stress
Reverse Voltage (E+ to E–) −20 V rating only and functional operation of the device at these or
Breakdown Voltage (Case E+ or E–) ±200 V any other conditions above those indicated in the operational
Rated Performance Temperature Range1 −55°C to +150°C section of this specification is not implied. Exposure to absolute
Storage Temperature Range1 −65°C to +155°C maximum rating conditions for extended periods may affect
Lead Temperature (Soldering, 10 sec) 300°C device reliability.
1
The 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.

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.

Rev. C | Page 5 of 16
AD590

PRODUCT DESCRIPTION
The AD590H has 60 µ inches of gold plating on its Kovar leads PTAT current. Figure 4 is the schematic diagram of the AD590.
and Kovar header. A resistance welder is used to seal the nickel In this figure, Q8 and Q11 are the transistors that produce the
cap to the header. The AD590 chip is eutectically mounted to PTAT voltage. R5 and R6 convert the voltage to current. Q10,
the header and ultrasonically bonded to with 1 mil aluminum whose collector current tracks the collector currents in Q9 and
wire. Kovar composition: 53% iron nominal; 29% ±1% nickel; Q11, supplies all the bias and substrate leakage current for the
17% ±1% cobalt; 0.65% manganese max; 0.20% silicon max; rest of the circuit, forcing the total current to be PTAT. R5 and
0.10% aluminum max; 0.10% magnesium max; 0.10% R6 are laser-trimmed on the wafer to calibrate the device at
zirconium max; 0.10% titanium max; 0.06% carbon max. 25°C.

The AD590F is a ceramic package with gold plating on its Kovar Figure 5 shows the typical V–I characteristic of the circuit at
leads, Kovar lid, and chip cavity. Solder of 80/20 Au/Sn 25°C and the temperature extremes.
composition is used for the 1.5 mil thick solder ring under the +
lid. The chip cavity has a nickel underlay between the R1 R2
metallization and the gold plating. The AD590 chip is 260Ω 1040Ω

eutectically mounted in the chip cavity at 410°C and Q2 Q5 Q3

Q1 Q4
ultrasonically bonded to with 1 mil aluminum wire. Note that
C1
the chip is in direct contact with the ceramic base, not the metal Q6 26pF
lid. When using the AD590 in die form, the chip substrate must
Q7 Q12 Q8
be kept electrically isolated (floating) for correct circuit
operation.
R4
CHIP
SUBSTRATE R3 11kΩ
66MILS 5kΩ
Q9 Q10
Q11
V+

00533-C-004
8 R5 1 1
R6
146Ω
820Ω
–
42MILS
Figure 4. Schematic Diagram

V–

+150°C
423
00533-C-003

THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM;

CONSULT THE CHIP CATALOG FOR DETAILS +25°C
IOUT (µA)

298

Figure 3. Metalization Diagram –55°C

218
1
CIRCUIT DESCRIPTION
The AD590 uses a fundamental property of the silicon
00533-C-005

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 0 1 2 3 4 5 6 30
SUPPLY VOLTAGE (V)
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 Figure 5. V-1 Plot
electron) are constant, the resulting voltage is directly
proportional to absolute temperature (PTAT).
EXPLANATION OF TEMPERATURE SENSOR
In the AD590, this PTAT voltage is converted to a PTAT current
SPECIFICATIONS
by low temperature coefficient thin-film resistors. The total
current of the device is then forced to be a multiple of this 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
1
For a more detailed description, see M.P. Timko, “A Two-Terminal IC supply voltage and thermal environment on accuracy.
Temperature Transducer,” IEEE J. Solid State Circuits, Vol. SC-11, p. 784-788,
Dec. 1976. Understanding the Specifications–AD590.

Rev. C | Page 6 of 16
 AD590
The AD590 is basically a PTAT (proportional to absolute 5V +
+
temperature)1 current regulator. That is, the output current is AD590
–
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 R

100Ω
factory, by adjusting the indicated temperature (that is, the VT = 1mV/K

00533-C-007
950Ω
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 Figure 7. One Temperature Trim
tested for accuracy over temperature. ERROR VERSUS TEMPERATURE: WITH
CALIBRATION ERROR CALIBRATION ERROR TRIMMED OUT
Each AD590 is tested for error over the temperature range with
At final factory test, the difference between the indicated
the calibration error trimmed out. This specification could also
temperature and the actual temperature is called the calibration
be called the “variance from PTAT,” because it is the maximum
error. Since this is a scale factory error, its contribution to the
difference between the actual current over temperature and a
total error of the device is PTAT. For example, the effect of the
PTAT multiplication of the actual current at 25°C. This error
1°C specified maximum error of the AD590L varies from
consists of a slope error and some curvature, mostly at the
0.73°C at –55°C to 1.42°C at 150°C. Figure 6 shows how an
temperature extremes. Figure 8 shows a typical AD590K
exaggerated calibration error would vary from the ideal over
temperature curve before and after calibration error trimming.
temperature.

ACTUAL 2
TRANSFER BEFORE
FUNCTION ABSOLUTE ERROR (°C) CALIBRATION
TRIM

CALIBRATION
IACTUAL ERROR
IOUT (µA)

CALIBRATION IDEAL
ERROR TRANSFER
FUNCTION 0
298.2

AFTER
CALIBRATION
TRIM

00533-C-008
00533-C-006

–2
–55 150
298.2
TEMPERATURE (°C)
TEMPERATURE (°K)
Figure 8. Effect to Scale Factor Trim on Accuracy
Figure 6. Calibration Error vs. Temperature

The calibration error is a primary contributor to maximum

ERROR VERSUS TEMPERATURE: NO USER TRIMS
total error in all AD590 grades. However, since it is a scale factor Using the AD590 by simply measuring the current, the total
error, it is particularly easy to trim. Figure 7 shows the most error is the variance from PTAT, described above, plus the effect
elementary way of accomplishing this. To trim this circuit, the of the calibration error over temperature. For example, the
temperature of the AD590 is measured by a reference AD590L maximum total error varies from 2.33°C at –55°C to
temperature sensor and R is trimmed so that VT = 1 mV/K at 3.02°C at 150°C. For simplicity, only the large figure is shown on
that temperature. Note that when this error is trimmed out at the specification page.
one temperature, its effect is zero over the entire temperature
NONLINEARITY
range. In most applications there is a current-to-voltage
conversion resistor (or, as with a current input ADC, a Nonlinearity as it applies to the AD590 is the maximum
reference) that can be trimmed for scale factor adjustment. 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.

1
T(°C) = T(K) –273.2. Zero on the Kelvin scale is “absolute zero”; there is no
lower temperature.

Rev. C | Page 7 of 16
AD590

1.6
VOLTAGE AND THERMAL ENVIRONMENT EFFECTS
The power supply rejection specifications show the maximum
expected change in output current versus input voltage changes.
ABSOLUTE ERROR (°C)

0.8 The insensitivity of the output to input voltage allows the use of
0.8°C MAX unregulated supplies. It also means that hundreds of ohms of
resistance (such as a CMOS multiplexer) can be tolerated in
0
series with the device.
0.8°C 0.8°C
MAX MAX
It is important to note that using a supply voltage other than 5 V
–0.8
does not change the PTAT nature of the AD590. In other words,

00533-C-009
this change is equivalent to a calibration error and can be
–1.6 removed by the scale factor trim (see Figure 8).
–55 150
TEMPERATURE (°C)
The AD590 specifications are guaranteed for use in a low
Figure 9. Nonlinearity thermal resistance environment with 5 V across the sensor.
Figure 10 shows a circuit in which the nonlinearity is the major Large changes in the thermal resistance of the sensor’s
contributor to error over temperature. The circuit is trimmed by environment change the amount of self-heating and result in
adjusting R1 for a 0 V output with the AD590 at 0°C. R2 is then changes in the output, which are predictable but not necessarily
adjusted for 10 V out with the sensor at 100°C. Other pairs of desirable.
temperatures may be used with this procedure as long as they The thermal environment in which the AD590 is used
are measured accurately by a reference sensor. Note that for determines two important characteristics: the effect of self-
15 V output (150°C) the V+ of the op amp must be greater than heating and the response of the sensor with time. Figure 12 is a
17 V. Also note that V− should be at least −4 V; if V− is ground, model of the AD590 that demonstrates these characteristics.
there is no voltage applied across the device.
TJ θJC TC θCA
15V
+
R1 R2

00533-C-012
P CCH CC TA
35.7kΩ 2kΩ 97.6kΩ 5kΩ
–
AD581
30pF
Figure 12. Thermal Circuit Model
27kΩ
100mV/°C As an example, for the TO-52 package, θJC is the thermal
AD707A VT = 100mV/°C
resistance between the chip and the case, about 26°C/W. θCA is
00533-C-010

AD590
the thermal resistance between the case and the surroundings
V–
and is determined by the characteristics of the thermal
Figure 10. 2-Temperature Trim connection. Power source P represents the power dissipated on
the chip. The rise of the junction temperature, TJ, above the
ambient temperature TA is
2
TJ − TA = P (θ JC + θ CA )
TEMPERATURE (°C)

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
0
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
00533-C-011

conditions in still air, the temperature rise is 0.72°C. For a given

–2
supply voltage, the temperature rise varies with the current and
–55 0 100 150 is PTAT. Therefore, if an application circuit is trimmed with the
TEMPERATURE (°C)
sensor in the same thermal environment in which it will be
Figure 11. Typical 2-Trim Accuracy used, the scale factor trim compensates for this effect over the
entire temperature range.

Rev. C | Page 8 of 16
 AD590
Table 4. Thermal Resistance response, T (t). Table 4 shows the effective time constant, τ, for
θJC + θCA (°C/Watt) τ (sec)1 several media.
Medium H F H F
Aluminum Block 30 10 0.6 0.1
TFINAL
Stirred Oil2 42 60 1.4 0.6
Moving Air3

SENSED TEMPERATURE
With Heat Sink 45 – 5.0 –
Without Heat Sink 115 190 13.5 10.0
Still Air
T(t) = TINITIAL + (TFINAL – TINITIAL) × (1 – e–t/τ)
With Heat Sink 191 – 108 –
Without Heat Sink 480 650 60 30
1
τ is dependent upon velocity of oil; average of several velocities listed above.

00533-C-013
2
Air velocity @ 9 ft/sec.
3
The time constant is defined as the time required to reach 63.2% of an
instantaneous temperature change. TINITIAL
τ 4τ
The time response of the AD590 to a step change in TIME
temperature is determined by the thermal resistances and the
Figure 13. Time Response Curve
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

Rev. C | Page 9 of 16
AD590

GENERAL APPLICATIONS
V+
Figure 14 demonstrates the use of a low cost digital panel meter
for the display of temperature on either the Kelvin, Celsius, or + R3
AD590L 10kΩ
Fahrenheit scales. For Kelvin temperature, Pins 9, 4, and 2 are #2
–
grounded; for Fahrenheit temperature, Pins 4 and 2 are left
–
open.
+ R1
AD707A
5V AD590L 5MΩ (T1 – T2) × (10mV/°C)
#1 R2 +
– R4
50kΩ
10kΩ
OFFSET

00533-C-016
8 9
6 CALIBRATION
+
GAIN V–
AD590 AD2040 4 SCALING
–
5 2 OFFSET Figure 16. Differential Measurements
3 SCALING
00533-C-014 Figure 17 is an example of a cold junction compensation circuit
GND for a Type J thermocouple using the AD590 to monitor the
reference junction temperature. This circuit replaces an ice-bath
Figure 14. Variable Scale Display as the thermocouple reference for ambient temperatures
between 15°C and 35°C. The circuit is calibrated by adjusting RT
The above configuration yields a 3-digit display with 1°C or 1°F
for a proper meter reading with the measuring junction at a
resolution, in addition to an absolute accuracy of ±2.0°C over
known reference temperature and the circuit near 25°C. Using
the −55°C to +125°C temperature range, if a one-temperature
components with the TCs as specified in Figure 17,
calibration is performed on an AD590K, AD590L, or AD590M.
compensation accuracy is within ±0.5°C for circuit
Connecting several AD590 units in series as shown in Figure 15 temperatures between 15°C and 35°C. Other thermocouple
allows the minimum of all the sensed temperatures to be types can be accommodated with different resistor values. Note
indicated. In contrast, using the sensors in parallel yields the that the TCs of the voltage reference and the resistors are the
average of the sensed temperatures. primary contributors to error.
15V 7.5V

+
IRON
AD590 REFERENCE
– 5V JUNCTION
+
+ CONSTANTAN
AD590 + + +
AD590
–
– AD590
+ – – – +
AD590 –
– + AD580 52.3Ω CU
+ + MEASURING
10kΩ VT MIN 333.3Ω VT AVG JUNCTION
VOUT
00533-C-015

(0.1%) (0.1%) – + –
– – 8.66kΩ
METER
RT
Figure 15. Series and Parallel Connection 1kΩ
00533-C-017
The circuit in Figure 16 demonstrates one method by which RESISTORS ARE 1%, 50PPM/°C

differential temperature measurements can be made. R1 and R2

can be used to trim the output of the op amp to indicate a Figure 17. Cold Junction Compensation Circuit for Type J Thermocouple
desired temperature difference. For example, the inherent offset Figure 18 is an example of a current transmitter designed to be
between the two devices can be trimmed in. If V+ and V− are used with 40 V, 1 kΩ systems; it uses its full current range of
radically different, then the difference in internal dissipation 4 mA to 20 mA for a narrow span of measured temperatures. In
causes a differential internal temperature rise. This effect can be this example, the 1 µA/K output of the AD590 is amplified to
used to measure the ambient thermal resistance seen by the 1 mA/°C and offset so that 4 mA is equivalent to 17°C and
sensors in applications such as fluid-level detectors or 20 mA is equivalent to 33°C. RT is trimmed for proper reading
anemometry. at an intermediate reference temperature. With a suitable choice
of resistors, any temperature range within the operating limits
of the AD590 may be chosen.

Rev. C | Page 10 of 16
 AD590
V+ 20pF

4mA = 17°C
+ AD581
12mA = 25°C 1.25kΩ
20mA = 33°C – VOUT
35.7kΩ REF
–15V
30pF DAC OUT MC
+ RT +5V
–
AD590 5kΩ 1408/1508 1.15kΩ
– AD707A BIT 1 BIT 8
200Ω, 15T
+ 5kΩ 500Ω BIT 2 BIT 7 +5V
12.7kΩ
BIT 3 BIT 6 +2.5V
AD580
0.01µF BIT 4 BIT 5
10kΩ 10Ω
200Ω

00533-C-018
+5V +5V
V– 6.98kΩ
1kΩ
1kΩ, 15T
Figure 18. 4 mA to 20 mA Current Transmitter 3 OUTPUT HIGH-
8
+ 7 TEMPERATURE ABOVE SET POINT
LM311
Figure 19 is an example of a variable temperature control circuit AD590 2 1 OUTPUT LOW-
– 4 TEMPERATURE BELOW SET POINT
(thermostat) using the AD590. RH and RL are selected to set the 5.1MΩ
–15V
–15V
high and low limits for RSET. RSET could be a simple pot, a

00533-C-020
calibrated multiturn pot, or a switched resistive divider. 6.8kΩ

Powering the AD590 from the 10 V reference isolates the

AD590 from supply variations while maintaining a reasonable Figure 20. DAC Set Point
voltage (~7 V) across it. Capacitor C1 is often needed to filter
The voltage compliance and the reverse blocking characteristic
extraneous noise from remote sensors. RB is determined by the
of the AD590 allows it to be powered directly from 5 V CMOS
β of the power transistor and the current requirements of the
logic. This permits easy multiplexing, switching, or pulsing for
load.
minimum internal heat dissipation. In Figure 21, any AD590
V+ connected to a logic high passes a signal current through the
V+
AD581 current measuring circuitry, while those connected to a logic
OUT 10V
HEATING zero pass insignificant current. The outputs used to drive the
V– + ELEMENTS
RB AD590s may be employed for other purposes, but the additional
RH AD590
– 2 – 7 capacitance due to the AD590 should be taken into account.
RSET
LM311 5V
1
RL 3 +
4
C1
10kΩ
00533-C-019

+
GND AD590
CMOS + –
GATES
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
1kΩ (0.1%)
hysteresis, which is usually necessary to guard-band for
00533-C-021

extraneous noise. Omitting the 5.1 MΩ resistor results in no

hysteresis.
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.

Rev. C | Page 11 of 16
AD590
The inhibit input on the multiplexer turns all sensors off for up to eight channels of ±0.5°C absolute accuracy over the
minimum dissipation while idling. 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;
Figure 23 demonstrates a method of multiplexing the AD590 in output to 150°C can be achieved by using a 20 V supply for the
the two-trim mode (see Figure 10 and Figure 11). Additional op amp.
AD590s and their associated resistors can be added to multiplex

10V

16 0
3
1
14
2
2
4028 + + +
CMOS + + +
BCD-TO- AD590
DECIMAL + – 02 + – 01 + – 00
– – –
11 DECODER 12 11 10
– 22 – 21 – 20
ROW 12
SELECT 13
10
8

10V
2 1 0
16 15 14 13

9
10 LOGIC 4051 CMOS ANALOG
COLUMN LEVEL
SELECT MULTIPLEXER
11 INTERFACE
6
INHIBIT BINARY TO 1-OF-8 DECODER

7 8

10kΩ 10mV/°C

00533-C-022
Figure 22. Matrix Multiplexer

2kΩ 5kΩ
+15V 35.7kΩ 97.6kΩ

+ 2kΩ 5kΩ
35.7kΩ 97.6kΩ
AD581
– VOUT
V+

S1
AD707A
10mV/°C
S2

DECODER/
DRIVER –15V
27kΩ
S8

AD7501
+15V
TTL/DTL TO CMOS
–15V INTERFACE

+ + EN
AD590L AD590L BINARY
– – CHANNEL
SELECT
00533-C-023

–5V TO –15V

Figure 23. 8-Channel Multiplexer

Rev. C | Page 12 of 16
 AD590

OUTLINE DIMENSIONS
0.230 (5.84)
0.209 (5.31)
0.195 (4.95) 0.150 (3.81)
0.178 (4.52) 0.115 (2.92)
0.050
0.030 (0.76) (1.27)
MAX MAX

0.019 (0.48)
0.500
0.016 (0.41) (12.70)
MIN
0.021 (0.53) 0.250 (6.35)
POSITIVE LEAD MAX MIN
0.019 (0.48)
INDICATOR
0.017 (0.43)
0.015 (0.38) 0.050 (1.27) T.P.

0.093 (2.36) 0.048 (1.22)

3
0.081 (2.06)
0.100 0.028 (0.71)
0.055 (1.40)
(2.54) 2
0.050 (1.27) T.P.
0.045 (1.14) 0.046 (1.17)
0.500 (12.69) 1
0.230 (5.84) 0.050 0.036 (0.91)
MIN
(1.27)
0.250 (6.35)
T.P.
45 T.P.
0.0065 (0.17) 0.050 (1.27)
0.0050 (0.13) 0.041 (1.04) CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETERS DIMENSIONS
0.0045 (0.12)
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN

Figure 24. 2-Lead Ceramic Flat Package [CQFP] Figure 25. 3-Pin Metal Header Package [TO-52]
(F-2) (H-03)
Dimensions shown in inches and (millimeters) Dimensions shown in inches and (millimeters)

5.00 (0.1968)
4.80 (0.1890)

8 5
4.00 (0.1574) 6.20 (0.2440)
3.80 (0.1497) 1 4 5.80 (0.2284)

1.27 (0.0500) 0.50 (0.0196)

BSC 1.75 (0.0688) × 45°
0.25 (0.0099)
0.25 (0.0098) 1.35 (0.0532)
0.10 (0.0040)
0.51 (0.0201) 8°
COPLANARITY 0.25 (0.0098) 0° 1.27 (0.0500)
0.10 SEATING 0.31 (0.0122) 0.40 (0.0157)
PLANE 0.17 (0.0067)

COMPLIANT TO JEDEC STANDARDS MS-012AA

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

Figure 26. 8-Lead Standard Small Outline Package [SOIC]

Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)

Rev. C | Page 13 of 16
AD590
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
1
Available in 883B; consult factory for data sheet.

Rev. C | Page 14 of 16
 AD590

NOTES

Rev. C | Page 15 of 16
AD590

NOTES

© 2003 Analog Devices, Inc. All rights reserved. Trademarks and

registered trademarks are the property of their respective owners.
C00533–0–9/03(C)

Rev. C | Page 16 of 16