Omega Products AD590L Installation Manual

AD590JFAD590JF AD590KF

User’s Guide

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AD590

Temperature Sensors

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.

w

2-Terminal IC

–

Temperature Transducer

FEATURES

Linear current output: 1 µA/K
Wide temperature range: −55°C to +150°C
Pr

obe-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

isolation from case

Sensor
Low cost

GENERAL DESCRIPTION

e AD590 is a 2-terminal integrated circuit temperature
tran

sducer that produces an output current proportional to

absolute temperature. For supply voltages between 4 V and

V, the device acts as a high impedance, constant current

30
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).

e

AD590 should be used in any temperature-sensing
application below 150°C in which conventional electrical
temperature sensors are currently employed. e 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.

AD590

PIN CONFIGURATIONS

NC

1

2

V+

TOP VIEW

(Not to Scale)

V–

3

4

420-3

3
500

+ –

Fi

gure 1. 2-Lead CQFP Figure 2. 8-Lead SOIC

+

gure 3. 3-Pin TO-52

Fi

5
2
0-

3
35

0

NC

NC = NO CONNECT

PRODUCT HIGHLIGHTS

1. e 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
ci

rcuits 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
AD

590 units are easily interchangeable.

NC

8

7

NC

NC

6

5

NC

100

­33500

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.
e

AD590 is available in chip form, making it suitable for
hybrid circuits and fast temperature measurements in
protected environments.

e AD590 is particularly useful in remote sensing applications.
e

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. e output characteristics also make the

easy to multiplex: the current can be switched by a

AD590

3. Superior interface rejection occurs because the output is a
current rather than a voltage. In addition, power
requirements are low (1.5 mW @ 5 V @ 25°C). ese
features make the AD590 easy to apply as a remote sensor.

4. e high output impedance (>10 MΩ) provides excellent
rejection of supply voltage dri and ripple. For instance,

ging the power supply from 5 V to 10 V results in only

chan
a 1 µA maximum current change, or 1°C equivalent error.

5. e AD590 is electrically durable: it withstands a forward
voltage of up to 44 V and a reverse voltage of 20 V.
e

refore, supply irregularities or pin reversal does not

damage the device.

CMOS multiplexer, or the supply voltage can be switched by a
lo

gic gate output.

AD590

TABLE OF CONTENTS

Features.............................................................................................. 1

Ge

neral Description ......................................................................... 1

Explanation of Temperature Sensor Specifications ..................7

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

Configurations ...........................................................................1

Pin

Product Highlights ........................................................................... 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

AD590J

AD590L

Absolute Maximum Ratings............................................................ 5

ESD Caution.................................................................................. 5

Ge

Circuit Description....................................................................... 6

and AD590K Specifications ......................................... 3

and AD590M Specifications ....................................... 4

neral Description ......................................................................... 6

Error vs. Temperature: with Calibration Error Trimmed

Out...................................................................................................7

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

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

Voltage and ermal Environment Effects ...............................8

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

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

Page 2 of 16

AD590

SPECIFICATIONS

AD590J AND AD590K SPECIFICATIONS

25°C and VS = 5 V, unless otherwise noted.

Table 1.

AD590J AD590K
Parameter Min Typ Max Min Typ Max Unit

POWER SUPPLY
Operating Voltage Range
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 CQFP Packages
For 8-Lead SOIC Package
Repeatability

Long-Term Drift

2

3

Current Noise 40 40
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 10
Effective Shunt Capacitance 100 100 pF
Electrical Turn-On Time 20 20 µs
Reverse Bias Leakage Current (Reverse Voltage = 10 V)

1

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

minimum

2

Maximum deviation between +25°C readings after temperature cycling between −55°C and +150°C; guaranteed, not tested.

3

Conditions: constant 5 V, constant 125°C; guaranteed, not tested.

4

Leakage current doubles every 10°C.

and maximum specifications are guaranteed, although only those shown in boldface are tested on all production units.

1

4

30

±5.0

±10
±3.0

±1.5
±1.5

4

30 V

±2.5

±5.5
±2.0

±0.8
±1.0

°C

°C
°C

°C

°C
±0.1 ±0.1 °C
±0.1 ±0.1 °C

pA/√Hz

10

10

4

10 10 pA

10

Ω

Page 3 of 16

AD590

K°C

AD590L AND AD590M SPECIFICATIONS

25°C and VS = 5 V, unless otherwise noted.

Table 2.

AD590L AD590M
Parameter Min Typ Max Min Typ Max Unit

POWER SUPPLY

Operating Voltage Range 4 30 4 30 V

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
Repeatability
Long-Term Drift

2

3

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 10
Effective Shunt Capacitance 100 100 pF
Electrical Turn-On Time 20 20 µs
Reverse Bias Leakage Current (Reverse Voltage = 10 V)

1

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

minimum and maximum specifications are guaranteed, although only those shown in boldface are tested on all production units.

2

Maximum deviation between +25°C readings after temperature cycling between –55°C and +150°C; guaranteed, not tested.

3

Conditions: constant 5 V, constant 125°C; guaranteed, not tested.

4

Leakage current doubles every 10°C.

1

±0.1 ±0.1 °C
±0.1 ±0.1 °C

10

10

4

10 10 pA

10

Ω

+223°

°

°F

–50

°

–100° 0° +100° +200° +300°

Figure 4. Temperature Scale Conversion Equations

+273°0°+298°

+32° +70° +212°

5
9

9

°F = °C + 32)

5

+25°

(

(

+323°

+50°

32)

+373°

+100°

+ 273.15°C = °F – K = °C

+423°

+150°

2
0
0

­3
3
5
00

+ 459.7R = °F

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 was used at −100°C and +200°C for short periods of

mea

surement with no physical damage to the device. However, the absolute

erro

rs 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

ctrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance

ele

ation or loss of functionality.

degrad

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. is 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
ma

ximum rating conditions for extended periods may affect

device reliability.

Page 5 of 16

AD590

(

GENERAL DESCRIPTION

e 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. e 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% co

balt; 0.65% manganese max; 0.20% silicon max;

0.10% aluminum max; 0.10% magnesium max; 0.10% zirconium
max; 0.10%

e AD590F is

titanium max; and 0.06% carbon max.

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
li

d. e chip cavity has a nickel underlay between the metallization
and the gold plating. e 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
cer

amic 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.

66

MILS

V+

42MILS

PTAT current.
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 7 shows the typical V–I characteristic of the circuit at
25°C a

nd the temperature extremes.

Figure 6 is the schematic diagram of the AD590.

+

R1

R2

26

0Ω

1040Ω

Q2

Q1

Q7

SUBSTRATE

R6
82

0Ω

Figure 6

Q5 Q3

C1

R3
5kΩ

26pF

R4
11kΩ

Q10Q9

CH

Q6

–

IP

Q12

R5

146Ω

. Schematic Diagram

Q8

Q4

Q11

40

118

0

­33

500

V–

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

Fi

gure 5. Metallization Diagram

CIRCUIT DESCRIPTION

1

e AD590 uses a fundamental property of the silicon
transistors from which it is made to realize its temperature
pro

portional characteristic: if two identical transistors are
operated at a constant ratio of collector current densities, r,
then the difference in their base-emitter voltage is (kT/q)(In r).
Because both k (Boltzman’s constant) and q (the charge of an
electron) are constant, the resulting voltage is directly

portional to absolute temperature (PTAT).

pro

In the AD590, this PTAT voltage is converted to a PTAT current
by low temperature coefficient thin-film resistors. e total
current of the device is then forced to be a multiple of this

423

30
0

­3350

0

)
A

298

µ

T
U
O

I

218

0 1 2

1

For a more detailed description, see M.P. Timko, “A Two-Terminal IC

Temperature
Dec.

Transducer,” IEEE J. Solid State Circuits, Vol. SC-11, p. 784-788,

1976. Understanding the Specifications–AD590.

3 4

SUPPLY VOLTAGE (V)

. V–I Plot

Figure 7

+150°C

+25°C

–55°C

5 6 3

50
0-3

3
500

0

Page 6 of 16

AD590

(

V

EXPLANATION OF TEMPERATURE SENSOR
SPECIFICAT

e way in which the AD590 is specified makes it easy to apply
it in a wide variety of applications. It is important to understand
the meaning of the various specifications and the effects of the
suppl

y voltage and thermal environment on accuracy.

AD590 is a PTAT1 current regulator. at is, the output

e
current is equal to a scale factor times the temperature of the
sensor in degrees Kelvin. is 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. is is
done with 5 V across the device at a temperature within a few
de

grees of 25°C (298.2K). e device is then packaged and

tested for accuracy over temperature.

IONS

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.

calibration error would vary from the ideal over temperature.

)A

I

ACTUAL

µ

T
UO

298.2

I

LIBRATION

CA
ERROR

Figure 8 shows how an exaggerated

ACTUAL

TRANSFER

FUNCTION

IDEAL

TRANSFER

FUNCTION

+

5

–

Figur

+

AD590

–

+

R

0Ω

10

= 1mV/K

V

T

950Ω

–

e 9. One Temperature Trim

70
0

­3
3
5
0
0

ERROR VS. TEMPERATURE: WITH CALIBRATION
ERROR

Each AD590 is tested for error over the temperature range with
the calibration error trimmed out. is specification could also
be called the variance from PTAT, because it is the maximum
di
PTAT multiplication of the actual current at 25°C. is error
consists of a slope error and some curvature, mostly at the
temperature extremes.
temperature curve before and aer calibration error trimming.

TRIMMED OUT

fference between the actual current over temperature and a

Figure 10 shows a typical AD590K

2

)C
°(

RORR

E

ETUL

0

O
SBA

–2

BEFORE
CA

LIBRATION

TRIM

CALIBRATION

ERROR

AFTER
CA

LIBRATION

TRIM

–55 150

Figur

e 10. Effect to Scale Factor Trim on Accuracy

TEMPERATURE (°C)

8
00-

33
50
0

6
00-

335

298.2

TEMPERATURE (°K)

Figur

e 8. Calibration Error vs. Temperature

00

e calibration error is a primary contributor to the maximum
total error in all AD590 grades. However, because it is a scale
factor error, it is particularly easy to trim. Figure 9 shows the
most elementary way of accomplishing this. To trim this circuit,
the temperature of the AD590 is measured by a reference
te

mperature 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.

ERROR VS. 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 ma

3.02°C

ximum total error varies from 2.33°C at –55°C to

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
lin

e. e 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.
shows the nonlinearity of the typical AD590K from

1

T(°C) = T(K) − 273.2. Zero on the Kelvin scale is absolute zero; there is no

lower temperature.

Figure 11

Figure 10.

Page 7 of 16

AD590

V

R

A

1.6

)C°( RO

0.8

R
RE ETULOS

0

0.8°C
MAX

B
A

–0

.8

.6

–1

5 150

–5

TEMPERATURE (°C)

gure 11. Nonlinearity

Fi

0.8°C MAX

0.8°C
MAX

9
00

­3
3
5
00

Figure 12 shows a circuit in which the nonlinearity is the major
contributor to error over temperature. e circuit is trimmed
by adjusting R1 for a 0 V output with the AD590 at 0°C. R2 is
then adjusted for 10 V output with the sensor at 100°C. Other
pairs of temperatures can 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
th

an 17 V. Also, note that V− should be at least −4 V; if V− is

ground, there is no voltage applied across the device.

15

AD581

2

)
C°( E

R
U
T

E

0

P
MET

–2

R1

2kΩ

35.7kΩ

27kΩ

V–

e 12. 2-Temperature Trim

Figur

5 0 150100

–5

TEMPERATURE (°C)

Figure 13. Typical 2-Trim Accuracy

97.6kΩ

AD590

R2

5kΩ

30pF

AD707A

100mV/°C

= 100mV/°C

V

T

0
10-

33
500

11
0

­3
3
5
0
0

VOLTAGE AND THERMAL ENVIRONMENT EFFECTS

e power supply rejection specifications show the maximum
ex

pected change in output current vs. input voltage changes.

e in

sensitivity of the output to input voltage allows the use of

un

regulated 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

e 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.

thermal environment in which the AD590 is used

e

termines two important characteristics: the effect of self-

de
heating and the response of the sensor with time. Figure 14 is a
model of the AD590 that demonstrates these characteristics.

?

T

JC

J

P

C

CH

e 14. Thermal Circuit Model

Figur

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. e rise of the junction temperature, T
ambient temperature, T

T

− TA = P(θJC + θCA) (1)

J

A

, is

Table 4 gives the sum of θJC and θCA for several common
thermal media for both the H and F packages. e heat sink
use

d 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. erefore, if an application circuit is trimmed with the
sensor in the same thermal environment in which it is used, the
scale factor trim compensates for this effect over the entire
temperature range.

Figure 10).

T

?

CA

C

C

C

+

T

A

–

2
1
0

-33500

CA

, above the

J

is

Page 8 of 16

AD590

Table 4. ermal Resistance

θ

+ θCA

JC

(°C/

Watt)

τ (sec)

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

in

stantaneous temperature change.

e 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. e single time constant exponential
curve of
response, T (t).
se

Figure 15 is usually sufficient to describe the time

Table 4 shows the effective time constant, τ, for

veral media.

T

FINAL

E
RUTAREP

M
ET

DESNES

T

INITIAL

T(t) = T

INITIAL

τ

Figur

e 15. Time Response Curve

+ (T

FINAL

TIME

– T

INITIAL

4

τ

) × (1 – e

–t/τ

)

310-33500

Page 9 of 16

AD590

V

A

(

V

+

V

GENERAL APPLICATIONS

Figure 16 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, Pin 9, Pin 4, and
Pin

2 are grounded; for Fahrenheit temperature, Pin 4 and Pin 2

are le open.

5

OFFSET

9

4

2

LIBRATION

CA

GAIN
SCALING

OFFSET
SCALING

410

-3
3

5
00

D590

+

–

Figure 16.

6

5

8

AD2040

3

GND

Variable Scale Display

e 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

libration is performed on an AD590K, AD590L, or AD590M.

ca

Connecting several AD590 units in series, as shown in

Figure 17,
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.

15

+

10

kΩ

0.1%)

AD590

–
+

AD590

–
+

AD590

–

+
MIN

V

T

–

e 17. Series and Parallel Connection

Figur

+

–

333

(0.1%)

.3Ω

5V

+

+

AD590

–

–

+

AVG

V

T

510-335

–

0
0

e circuit in Figure 18 demonstrates one method by which
di

fferential temperature measurements can be made. R1 and R2
can be used to trim the output of the op amp to indicate a
desi

red temperature difference. For example, the inherent offset
between the two devices can be trimmed in. If V+ and V− are
radi

cally different, then the difference in internal dissipation
causes a differential internal temperature rise. is effect can be
used to measure the ambient thermal resistance seen by the
sensors in applications such as fluid-level detectors or anemometry.

+

AD590L

#2

–

+

AD590L

#1

–

Figure 19 is an example of a cold junction compensation circuit
for a Type J thermocouple using the AD590 to monitor the
reference junction temperature. is circuit replaces an ice-bath
as

the thermocouple reference for ambient temperatures
between 15°C and 35°C. e 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
ac

curacy 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.

7.5

AD580

+

V

OUT

–

Figure 19. Cold Junction Compensation Circuit for Type J Thermocouple

V

R3

10

kΩ

–

R4
kΩ

AD707A

+

R1

R2

kΩ

50

Fi

5MΩ

10

V–

gure 18. Differential Measurements

Figure 19, compensation

REFERENCE

TION

JUNC

+

AD590

–

C

52.3Ω

8.66kΩ

1kΩ

R

T

U

+

METER

RESISTORS ARE 1%, 50ppm/°C

(T1 – T2) × (10mV/°C)

IRON

+

–

MEASURING

–

JUNC

61
0

-33

50
0

CONSTANTAN

TION

T

7
1
0-

3
35

00

Page 10 of 16

AD590

V

4m

m

20m

V

F

V

A

Figure 20 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
to 20 mA for a narrow span of measured temperatures. In this
ex

ample, the 1 µA/K output of the AD590 is amplified to

/°C and offset so that 4 mA is equivalent to 17°C and

1 mA
20 mA is e

quivalent 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 can be chosen.

+

+

12

0.01µF

A = 17°C

A = 25°C
A = 33°C

AD590

AD581

V

OUT

–

+

–

10

kΩ

35.7kΩ

5kΩ

12.7kΩ

10Ω

R

T

30pF

–

AD707A

+

5kΩ 500Ω

8
1
0-

3
3
5

V–

00

Figure 20. 4 to 20 mA Current Transmitter

Figure 21 is an example of a variable temperature control circuit

hermostat) using the AD590. R

(t

gh and low limits for R

hi

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)
ac

ross it. Capacitor C1 is oen needed to filter extraneous noise

from remote sensors. R

is determined by the β of the power

B

transistor and the current requirements of the load.

+

AD581

V+

OUT

V–

10

V

R

H

AD590

R

SET

R

L

gure 21. Simple Temperature Control Circuit

Fi

+

–

2

–

3

+

C1

10

kΩ

7

LM311

4

R

1

GND

HEATING

B

ELEMENTS

91
0

­33500

20p

1.25kΩ

–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

3

LM311

2

–15V

6.8kΩ

MC

+5V +5V

8

1

4

Figure 22. DAC

REF

+5V

1.15kΩ

200Ω, 15T

+5V

+2.5V

200Ω

1kΩ

OUTPUT HIGH­TEMPERATURE ABOVE SETPOINT

7

OUTPUT LOW­TEMPERATURE BELOW SETPOINT

5.1MΩ

Setpoint

AD580

02
0

-33

5
0
0

e voltage compliance and the reverse blocking characteristic
of the AD590 allow it to be powered directly from 5 V CMOS

gic. is permits easy multiplexing, switching, or pulsing for

lo
min

imum internal heat dissipation. In

Figure 23, 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. e outputs used to drive the
AD590s can

be employed for other purposes, but the additional

capacitance due to the AD590 should be taken into account.

5

+

D590

CMOS

GATES

+

–

+

–

gure 23. AD590 Driven from CMOS Logic

Fi

–

+

–

1kΩ (0.1%)

1
2
0-33

5
0

Figure 22 shows that the AD590 can be configured with an 8-bit
DAC to produce a digitally controlled setpoint. is particular
circuit operates from 0°C (all inputs high) to 51.0°C (all inputs
low) in 0.2°C steps. e 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.

Page 11 of 16

AD590

V

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.
the principle demonstrated in
CMOS

multiplexer. e resulting circuit can select 1 to 80

Figure 24 shows a circuit that combines

Figure 23 with an 8-channel

sensors over only 18 wires with a 7-bit binary word.

10

0

3

1

14

2

2

SE

ROW

LECT

11
12
13
10

16

4028

CMOS

-TO-

BCD

DECIMAL

DECODER

8

+

–

22

e i

nhibit input on the multiplexer turns all sensors off for

min

imum dissipation while idling.

Figure 25 demonstrates a method of multiplexing the AD590 in
the 2-trim mode (see

Figure 12 and Figure 13). 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. e high temperature restriction of

+

–

+

–

12

125°C is
150°C can

02

due to the output range of the op amps; output to

be achieved by using a 20 V supply for the op amp.

+

+

+

–

–

21

+

–

01

11

–

+

+

AD590

–

00

–

10

20

COLUMN

SELECT

INHIBIT

AD581

+15V

+

–

9

10

11

6

V

OUT

10V

16

LOGIC
LEVEL

INTERFACE

7 8

35.7kΩ

35.7kΩ

2kΩ

2kΩ

BINARY TO 1-OF-8 DECODER

gure 24. Matrix Multiplexer

Fi

5kΩ

97.6kΩ

5kΩ

97.6kΩ

S1

S2

DECODER/

S8

AD7501

+15V

–15V

TTL/DTL TO CMOS

INTERFACE

DR

15

IVER

0131142

27

51 CMOS ANALOG

40

MULTIPLEXER

10kΩ 10mV/°C

V+

AD707A

–15V

kΩ

10mV/°C

22
0-3

35
0

0

+

+

AD590L

–5V TO –15V

AD590L

–

–

gure 25. 8-Channel Multiplexer

Fi

EN

BINARY

CHANNEL

SELECT

3
2
0

­3
3
5
00

Page 12 of 16

AD590

OUTLINE DIMENSIONS

0.030 (0.76)

0.019 (0.48)

0.017 (0.43)

0.015 (0.38)

0.055 (1.40)

0.050 (1.27)

0.045 (1.14)

TYP

0.500 (12.69)
MIN

0.0065 (0.17)

0.0050 (0.13)

0.0045 (0.12)

Figure 26. 2-Lead Ceramic Flat Package [CQFP]

Dimensions shown in inches and (millimeters)

POSITIVE LEAD
INDICATOR

0.240 (6.10)

0.230 (5.84)

0.220 (5.59)

(F-2)

0.210 (5.34)

0.200 (5.08)

0.190 (4.83)

4.00 (0.1574)

3.80 (0.1497)

0.093 (2.36)

0.081 (2.06)

0.050 (1.27)

0.041 (1.04)

0.015 (0.38)
TYP

5.00 (0.1968)

4.80 (0.1890)

8 5

6.20 (0.2440)

5.80 (0.2284)

41

0.500 (12.70)

0.150 (3.81)

0.115 (2.92)

)59.4( 591.0

)2

)

)13.5( 902.0

4

5

8

.

.

4

5(

(
87

03

1

2

.

.0

0

0.030 (0.76) MAX

CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.

MIN

0.250 (6.35) MIN

0.050 (1.27) MAX

0.019 (0.48)

0.016 (0.41)

0.021 (0.53) MAX

BASE & SEATING PLANE

0.100
(2.54)

T.P.

0.050 (1.27) T.P.

2

0.050
(1.27)

T.P.

45° T.P.

0.048 (1.22)

0.028 (0.71)

0.046 (1.17)

0.036 (0.91)

3

1

Figure 27. 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)

COPLANARITY

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-012-AA

Fi

gure 28. 8-Lead Standard Small Outline Package [SOIC]

mensions shown in millimeters and (inches)

Di

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

rrow Body

Na

(R-8)

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)

× 45°

Page 13 of 16

AD590

NOTES:

Page 14 of 16

AD590

NOTES:

Page 15 of 16

AD590

NOTES:

Page 16 of 16

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a
period of 13 months from date of purchase. OMEGA’s WARRANTY adds an additional one (1) month
grace period to the normal one (1) year product warranty to cover handling and shipping time. This
ensures that OMEGA’s customers receive maximum coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Servic
Department will issue an Authorized Return (AR) number immediately upon phone or written request
Upon examination by OMEGA, if the unit is
charge. OMEGA’s WARRANTY does not

found to be defective, it will be repaired or replaced at no

apply to defects resulting from any action of the purchaser,
including but not limited to mishandling, improper interfacing, operation outside of design limits,
improper repair,
having been
or current,

or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of

tampered with or shows evidence of having been damaged as a result of excessive corrosion;

heat, moisture or vibration; improper specification; misapplication; misuse or other operating
conditions outside of OMEGA’s control. Components in which wear is not warranted, include but are not
limited to contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However,
OMEGA neither assumes responsibility for any omissions or errors nor assumes liability for any
damages that result from the use of its products in accordance with information provided by
OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by the
company will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR
REPRESENTATIONS OF ANY
TITLE, AND

ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY

KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF

AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF
LIABILITY: The remedies of purchaser set forth herein are exclusive, and the total liability of
OMEGA with respect to this order, whether based on contract, warranty, negligence,
indemnification, strict liability or otherwise, shall not exceed the purchase price of the
co mponent upo n whi ch liabilit y is based. In no event shal l OME GA be lia ble for
consequential, incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic
Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical
applications or used on humans. Should any Product(s) be used in or with any nuclear installation or
activity, medical
as set forth in our basic WARRANTY/DISCLAIMER language,
OMEGA

and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the

application, used on humans, or misused in any way, OMEGA assumes no responsibility

and, additionally, purchaser will indemnify

Product(s) in such a manner.

e

.

RETURN REQUESTS/INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE
RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETUR
(AR) NU M B ER FROM OM E G A’S CUSTOME R S ERV I CE DEPARTME N T ( IN ORDER T O AV OID
PROCESSING DELAYS). The assigned AR number should then be marked on the outside of the retur
package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to preven
breakage in transit.

FOR WARRANT
following information available BEFORE
contacting OMEGA

1. Purchase Order number under which the produc
was PURCHASED,

2. Model and serial number of the product unde
warranty, an

3. Repair instructions and/or specific problems
relative to the product.

OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords
our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC
© Copyright 2008 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,

reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without th
prior written consent of OMEGA ENGINEERING, INC

Y RETURNS, please have the

:

d

FOR NON-WARRANTY REPAIRS,

consult OMEGA
for current repair charges. Have the following
information available BEFORE contacting OMEGA

t

1. Purchase Order number to cover the COST

of the repair,

r

2. Model and serial number of the product, an

3. Repair instructions and/or specific problems

.

relative to the product.

.

d

N

n

t

:

e

Where Do I Find Everything I Need for

Process Measurement and Control?

OMEGA…Of Course!

Shop online at omega.com

SM

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