Datasheet AD590 Datasheet (Analog Devices)

Two-Terminal IC

K

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

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.

Temperature Transducer

AD590

FLATPAC

+–

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.

TO-52 SOIC-8

–

+

Figure 1. Pin Designations

NC

NC

1

V+

2

TOP VIEW

(Not to Scale)

3

V–

4

NC = NO CONNECT

NC

8

NC

7
6

NC

5

NC

00533-C-001

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

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
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.

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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
Fax: [phone] © 2003 Analog Devices, Inc. All rights reserved.

www.analog.com

AD590

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

REVISION HISTORY

Revision C

Error Versus Temperature: with Calibration Error Trimmed

...................................................................................................7

Out

Error Versus Temperature: No User Trims ................................7

Nonlinearity ...................................................................................7

Voltage and Thermal Environment Effects ...............................8

General Applications...................................................................... 10

Outline Dimensions....................................................................... 13

Ordering Guide .......................................................................... 14

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

OUTPUT

Nominal Current Output @ 25°C (298.2K) 298.2 298.2 µA
Nominal Temperature Coefficient 1 1 µA/K
Calibration Error @ 25°C
Absolute Error (over rated performance temperature range)

Without External Calibration Adjustment
With 25°C Calibration Error Set to Zero
Nonlinearity

For TO-52 and Flatpack packages

For 8-Lead SOIC package
Repeatability
Long-Term Drift

1

2

±0.1 ±0.1 °C

±0.1 ±0.1 °C
Current Noise 40 40
Power Supply Rejection

4 V ≤ VS ≤ 5 V
5 V ≤ VS ≤ 15 V
15 V ≤ VS ≤ 30 V

0.5 0.5 µA/V

0.2 0.2 µV/V

0.1 0.1 µA/V
Case Isolation to Either Lead 10
Effective Shunt Capacitance 100 100 pF
Electrical Turn-On Time 20 20 µs
Reverse Bias Leakage Current

3

(Reverse Voltage = 10 V) 10 10 pA

30

±5.0

±10
±3.0

±1.5
±1.5

10

1010

4

30 Volts

±2.5

±5.5
±2.0

±0.8
±1.0

°C

°C
°C

°C
°C

pA/√Hz

Ω

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

OUTPUT

Nominal Current Output @ 25°C (298.2K) 298.2
Nominal Temperature Coefficient 1
Calibration Error @ +25°C
Absolute Error (over rated performance temperature range)

Without External Calibration Adjustment
With ± 25°C Calibration Error Set to Zero
Nonlinearity
Repeatability
Long-Term Drift

1

2

Current Noise 40
Power Supply Rejection

4 V ≤ VS ≤ 5 V
5 V ≤ VS ≤ 15 V
15 V ≤ VS ≤ 30 V

Case Isolation to Either Lead 10
Effective Shunt Capacitance 100
Electrical Turn-On Time 20
Reverse Bias Leakage Current

3

(Reverse Voltage = 10 V) 10

4

30

±0.1
±0.1

±1.0

±3.0
±1.6
±0.4

0.5

0.2

0.1

10

4

298.2

1

40

0.5

0.2

0.1
10
100
20

10

30 Volts

±0.5

±1.7
±1.0
±0.3

±0.1 °C
±0.1 °C

10

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.

+223°

°K
°C

–50°

+273°0°+298°

+25°

+323°

+50°

+373°
+100°

+423°
+150°

µA
µA/K
°C
°C
°C
°C
°C

pA/√Hz

µA/V
µA/V
µA/V
Ω
pF
µs

pA

–100° 0° +100° +200° +300°

°F

Figure 2. Temperature Scale Conversion Equations

+32° +70° +212°

5
9

9

()

5

ooo

)

+=−=

CKFC

oooo

+=+=

FRCF

00533-C-002

15.27332

7.45932

Rev. C | Page 4 of 16

AD590

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 Range
Storage Temperature Range
Lead Temperature (Soldering, 10 sec) 300°C

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.

1

1

−55°C to +150°C

−65°C to +155°C

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.

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.

Rev. C | Page 5 of 16

AD590

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.

66MILS

V+

42MILS

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.

+

R

R

2

1

1040Ω

260Ω

Q

Q

1

2

Q

Q

7

CHIP

SUBSTRATE

Q

9

R

6

820Ω

–

6

Q

R

146Ω

Figure 4. Schem atic Diag ram

12

R
5kΩ

5

Q

Q

5

3

Q

4

C

1

26pF

Q

8

R

4

11kΩ

3

Q

10

Q

11

118

00533-C-004

V–

THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM;
CONSULT THE CHIP CATALOG FOR DETAILS

Figure 3. Metalization Diagram

CIRCUIT DESCRIPTION

1

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.

423

00533-C-003

298

(µA)

OUT

I

218

012

34

SUPPLY VOLTAGE (V)

+150°C

+25°C

–55°C

56 30

00533-C-005

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.

Rev. C | Page 6 of 16

AD590

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.

ACTUAL

TRANSFER

FUNCTION

I

(µA)
I

OUT

ACTUAL

298.2

CALIBRATION
ERROR

IDEAL

TRANSFER

FUNCTION

+

5V

–

100Ω

950Ω

R

+

AD590

–

= 1mV/K

V

T

+

00533-C-007

–

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.

2

0

ABSOLUTE ERROR (°C)

BEFORE
CALIBRATION
TRIM

CALIBRATION

ERROR

AFTER
CALIBRATION
TRIM

298.2

TEMPERATURE (°K)

00533-C-006

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 V

= 1 mV/K at

T

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.

–2

–55 150

TEMPERATURE (°C)

00533-C-008

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.

Rev. C | Page 7 of 16

AD590

A

(

)

=

−

1.6

0.8

0.8°C MAX

0

= 100mV/°C

T

0.8°C
MAX

00533-C-009

00533-C-010

0.8°C
MAX

ABSOLUTE ERROR (°C)

–0.8

–1.6

–55 150

TEMPERATURE (°C)

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.

15V

D581

R

1

2kΩ

35.7kΩ

27kΩ

V–

Figure 10. 2-Temperature Trim

2

97.6kΩ

AD590

R

2

5kΩ

30pF

AD707A

100mV/°C
V

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 self­heating and the response of the sensor with time. Figure 12 is a
model of the AD590 that demonstrates these characteristics.

θ

T

JC

J

P

C

CH

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. θ
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, T
ambient temperature T

is

A

J

Equation 1.

PTT θ+θ

θ

T

CA

C

+

T

CAJCA

A

–

, above the

J

00533-C-012

is

CA

C

C

Tabl e 4 gives the sum of θJC and θCA for several common

0

TEMPERATURE (°C)

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

–2

–55 0 150100

TEMPERATURE (°C)

Figure 11. Typical 2-Trim Accuracy

00533-C-011

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.

Rev. C | Page 8 of 16

AD590

Table 4. Thermal Resistance

θ

+ θCA (°C/Watt) τ (sec)

JC

1

Medium H F H F

Aluminum Block 30 10 0.6 0.1
Stirred Oil
Moving Air

2

3

42 60 1.4 0.6

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

1

τ is dependent upon velocity of oil; average of several velocities listed above.

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.

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, C
about 0.04 Ws/°C for the AD590. C

, and the case, CC. CCH is

CH

varies with the measured

C

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).
several media.

T

FINAL

SENSED TEMPERATURE

T

INITIAL

τ 4τ

Tabl e 4 shows the effective time constant, τ, for

+ (T

T(t) = T

INITIAL

FINAL

TIME

– T

INITIAL

Figure 13. Time Response Curve

) × (1 – e

–t/τ

)

00533-C-013

Rev. C | Page 9 of 16

AD590

A

(

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.

5V

8

AD2040

3

GND

D590

6

+

–

5

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.

15V

+

10kΩ

0.1%)

AD590

–
+

AD590

–
+

AD590

–

+

MIN

V

T

–

+

–

333.3Ω
(0.1%)

5V

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.

9

4

2

+

–

OFFSET
CALIBRATION

GAIN
SCALING

OFFSET
SCALING

+

AD590

–

+
AVG

V

T

–

00533-C-014

00533-C-015

V+

V–

R

1

5MΩ

R

10kΩ

3

10kΩ

–

AD707A

(T1 – T2) × (10mV/°C)

+

R

4

00533-C-016

+

AD590L

–

+

AD590L

–

#2

#1

R

2

50kΩ

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 R
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.

7.5V

IRON

CONSTANTAN

+
–

MEASURING

–

JUNCTION

00533-C-017

+

–

AD580

V

OUT

AD590

52.3Ω

8.66kΩ

1kΩ

+

–

R

T

REFERENCE
JUNCTION

C

U

+

METER

RESISTORS ARE 1%, 50PPM/°C

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. R

is trimmed for proper reading

T

at an intermediate reference temperature. With a suitable choice
of resistors, any temperature range within the operating limits
of the AD590 may be chosen.

T

Rev. C | Page 10 of 16

AD590

V+

+

4mA = 17°C
12mA = 25°C
20mA = 33°C

AD590

0.01µF

AD581

V

OUT

–

+

–

10kΩ

35.7kΩ

5kΩ

12.7kΩ

10Ω

R

T

30pF

–

AD707A

+

5kΩ 500Ω

V–

00533-C-018

Figure 18. 4 mA to 20 mA Current Transmitter

Figure 19 is an example of a variable temperature control circuit
(thermostat) using the AD590. R
high and low limits for R

SET

and RL are selected to set the

H

. R

could be a simple pot, a

SET

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 C
extraneous noise from remote sensors. R

is often needed to filter

1

is determined by the

B

β of the power transistor and the current requirements of the
load.

V+

AD581

V+

OUT

V–

10V

R

H

AD590

R

SET

R

L

+

–

2

3

C

1

10kΩ

–

LM311

+

R

B

7

1

4

GND

HEATING
ELEMENTS

00533-C-019

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.

20pF

1.25kΩ
REF
+5V

1.15kΩ
200Ω, 15T

+5V

+2.5V

200Ω

1kΩ
OUTPUT HIGH-

TEMPERATURE ABOVE SET POINT

7

OUTPUT LOW­TEMPERATURE BELOW SET POINT

5.1MΩ

AD580

00533-C-020

–15V

DAC OUT

BIT 1 BIT 8
BIT 2 BIT 7
BIT 3 BIT 6
BIT 4 BIT 5

6.98kΩ

1kΩ, 15T

+

AD590

–

–15V

1408/1508

+5V +5V

3

LM311

2

–15V

6.8kΩ

MC

4

8

1

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.

5V

+

AD590

CMOS

GATES

+

–

+

–

Figure 21. AD590 Driven from CMOS Logic

–

+

–

1kΩ (0.1%)

00533-C-021

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

Ω

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

10V

0

3

1

14

2

2

+

–

ROW

SELECT

DECODER

11
12
13
10

16

4028

CMOS

BCD-TO-

DECIMAL

8

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.

+

+

–

22

+

–

02

12

–

+

+

–

21

+

–

01

11

–

+

+

AD590

–

00

–

10

20

COLUMN

SELECT

INHIBIT

9
10
11
6

10V

16

LOGIC
LEVEL

INTERFACE

78

BINARY TO 1-OF-8 DECODER

0131142

15

4051 CMOS ANALOG
MULTIPLEXER

10kΩ 10mV/°C

00533-C-022

Figure 22. Matrix Multiplexer

AD581

+15V

+

–

2kΩ

35.7kΩ

2kΩ

35.7kΩ

V

OUT

5k

97.6kΩ

5kΩ

97.6kΩ

V+

S1

S2

DECODER/

DRIVER

S8

AD707A

27kΩ

10mV/°C

–15V

AD7501

AD590L

+

–

–5V TO –15V

+15V
–15V

+

–

AD590L

TTL/DTL TO CMOS

INTERFACE

EN

BINARY

CHANNEL

SELECT

00533-C-023

Figure 23. 8-Channel Multiplexer

Rev. C | Page 12 of 16

AD590

Y

OUTLINE DIMENSIONS

0.230 (5.84)

0.195 (4.95)

0.178 (4.52)

0.030 (0.76)
MAX

0.209 (5.31)

0.050
(1.27)

MAX

0.150 (3.81)

0.115 (2.92)

0.019 (0.48)

0.017 (0.43)

0.015 (0.38)

0.055 (1.40)

0.050 (1.27)

0.045 (1.14)

POSITIVE LEAD
INDICATOR

0.500 (12.69)
MIN

0.0065 (0.17)

0.0050 (0.13)

0.0045 (0.12)

0.230 (5.84)

0.250 (6.35)

Figure 24. 2-Lead Ceramic Flat Package [CQFP]

(F-2)

Dimensions shown in inches and (millimeters)

4.00 (0.1574)

3.80 (0.1497)

0.093 (2.36)

0.081 (2.06)

0.050 (1.27)

0.041 (1.04)

5.00 (0.1968)

4.80 (0.1890)

85

6.20 (0.2440)

5.80 (0.2284)

41

0.019 (0.48)

0.016 (0.41)

3

1

0.250 (6.35)

45 T.P.

MIN

0.048 (1.22)

0.028 (0.71)

0.046 (1.17)

0.036 (0.91)

0.021 (0.53)
MAX

0.050 (1.27) T.P.

0.100
(2.54)

T.P.

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

0.050

(1.27)

T.P.

2

0.500

(12.70)

MIN

Figure 25. 3-Pin Metal Header Package [TO-52]

(H-03)

Dimensions shown in inches and (millimeters)

1.27 (0.0500)
BSC

0.25 (0.0098)

0.10 (0.0040)

COPLANARIT

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

SEATING

PLANE

COMPLIANT TO JEDEC STANDARDS MS-012AA

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0196)

0.25 (0.0099)

8°

1.27 (0.0500)

0°

0.40 (0.0157)

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

× 45°

AD590

ORDERING GUIDE

Model Temperature Range Package Description Package Option

AD590JH
AD590JF
AD590JR −55°C to +150°C 8-Lead SOIC SOIC-8
AD590KH
AD590KF
AD590KR −55°C to +150°C 8-Lead SOIC SOIC-8
AD590LH
AD590LF
AD590MH
AD590MF
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.

1

1

1

1

1

1

1

1

−55°C to +150°C TO-52 H-03A

−55°C to +150°C Flatpack F-2A

−55°C to +150°C TO-52 H-03A

−55°C to +150°C Flatpack F-2A

−55°C to +150°C TO-52 H-03A

−55°C to +150°C Flatpack F-2A

−55°C to +150°C TO-52 H-03A

−55°C to +150°C Flatpack F-2A

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