OMEGA AD590 Manual

User’s Guide

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SM

AD590

Temperature Sensors

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The information contained in this document is believed to be correct, but OMEGA accepts no liability for any errors it contains, and reserves
the right to alter specifications without notice.

2-Terminal IC

–

Temperature Transducer

FEATURES

Linear current output: 1 µA/K

e temperature range: −55°C to +150°C

Wid
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

e AD590 is a 2-terminal integrated circuit temperature

cer that produces an output current proportional to

transdu
absol

ute temperature. For supply voltages between 4 V and
30 V, the device acts as a high impedance, constant current
regulator pas

istors is used to calibrate the device to 298.2 µA output at

res

298.2 K (

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

cost of a monolithic integrated circuit combined with the
elimination of
alternative for many temperature measurement situations.
Linearizati
measu
needed in applying

sing 1 µA/K. Laser trimming of the chip’s thin-film

25°C).

l electrical

support circuitry makes the AD590 an attractive

on circuitry, precision voltage amplifiers, resistance

ring circuitry, and cold junction compensation are not

the AD590.

AD590

PIN CONFIGURATIONS

NC

1

2

V+

TOP VIEW

(Not to Sc

V–

3

4

420-33500

+ –

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

+

F

igure 3. 3-P

520-3350

in TO-52

NC

NC = NO CONNECT

PRODUCT HIGHLIGHTS

1. e AD590 is a calibrated, 2-terminal temperature sensor
ng only a dc voltage supply (4 V to 30 V). Costly

requiri
transmitters, fil
circuits are all un

2. State-of-the-art laser trimming at the wafer level in

con

junction with extensive final testing ensures that

AD590 units

ters, lead wire compensation, and linearization

necessary in applying the device.

are easily interchangeable.

NC

8

7

NC

ale)

NC

6

5

NC

100-33500

In addition to temperature measurement, applications include
temperature compensation or c

asing proportional to absolute temperature, flow rate

bi
measurement

, level detection of fluids and anemometry.

e AD590 is available in chip

orrection of discrete components,

form, making it suitable for

hybrid circuits and fast temperature measurements in

otected environments.

pr

D590 is particularly useful in remote sensing applications.

e A
e device is insensitive to voltage drops over long
its high imped

ance current output. Any well-insulated twisted

pair is sufficient for operation at hundreds of

lines due to

feet from the
receiving circuitry. e output characteristics also make the
AD590 easy to multiplex: the current can be switched by a
CMOS multiplexer, or the su
logic

gate output.

pply voltage can be switched by a

uperior interface rejection occurs because the output is a

3. S
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
changing the power supply from
a 1 µ

supply voltage dri and ripple. For instance,

5 V to 10 V results in only

A maximum current change, or 1°C equivalent error.

5. e AD590 is electrically durable: it withstands a forward
voltage of
eref
damag

up to 44 V and a reverse voltage of 20 V.

ore, supply irregularities or pin reversal does not

e the device.

AD590

TABLE OF CONTENTS

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

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

General Description ...............................................................

Pin Config

Product Hig

Revision History ...............................................................

Specifications...............................................................

AD590J and AD590K Specifications ......................................... 3

AD590L and AD590M Specifications ....................................... 4

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

ESD Caution...............................................................

General Description ...............................................................

Circuit Description...............................................................

urations ........................................................................... 1

hlights ........................................................................... 1

.......... 1

................ 2

...................... 3

................... 5

.......... 6

........ 6

Ca

libration Error...........................................................................7

or vs. Temperature: with Calibration Error Trimmed

Err

Out...............................................................

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

Nonlinearity...............................................................

Voltage and ermal Envir

General Applications...............................................................

Outline Dimensions...............................................................

onment Effects ...............................8

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

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

....... 10

........ 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 and

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.

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

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.

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

1

±0.1 ±0.1 °C
±0.1 ±0.1 °C

10

10

4

10 10 pA

10

Ω

+223°

°

°

°F

–50°

00° 0° +100° +200° +300°

–1

+273°0°+298°

+32° +70° +21

5
9

9

°F = °C + 32)

5

+25°

(

(

+323°

+50°

32)

+373°

00°

+1

+ 273.15°C = °F – K = °C

2°

+ 459.7R = °F

Figure 4. Temperature Scale Conversion Equations

+42

+15

3°

0°

200-33500

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

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 perma

nent 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 thi
maximum rati

ice reliability.

dev

s specification is not implied. Exposure to absolute

ng conditions for extended periods may affect

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 hea

der and ultrasonically bonded to with 1 mil aluminum

e. Kovar composition: 53% iron nominal; 29% ± 1% nickel;

wir
17% ± 1% cobalt; 0.65% manganese max; 0.20% silicon max;

0.10% alu

minum max; 0.10% magnesium max; 0.10% zirconium

max; 0.10% titanium max; and 0.06% carbon max.

e 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 u

e chip cavity has a nickel underlay between the metallization

lid.
an

d the gold plating. e AD590 chip is eutectically mounted in

sed for the 1.5 mil thick solder ring under the

the chip cavity at 410°C and ultrasonically bonded to with 1 mil

minum wire. Note that the chip is in direct contact with the

alu
ceramic base, not the metal lid. When using the AD590 in die
form, the chip subst

rate must be kept electrically isolated

(floating) for correct circuit operation.

66MI

LS

V+

42MILS

PTAT current. Figure 6 is the schematic diagram of the AD5
In this figure, Q8 and Q11 are the tra

nsistors 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, f
R6 are l

aser-trimmed on the wafer to calibrate the device at 25°C.

orcing the total current to be PTAT. R5 and

Figure 7 shows the typical V–I characteristic of the circuit at
25°C and the temperature extremes.

+

R1

R2

260Ω

10

40Ω

Q2

Q1

BSTRATE

SU

R6

20Ω

8

Figure 6. Schemat

Q7

Q5 Q3

Q6

Q12

R5

146Ω

R3
5kΩ

R4
11kΩ

Q10Q9

C

HIP

–

C1

26pF

Q8

Q4

Q11

400-33500

118

ic Diagram

90.

V–

THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM;

THE CHIP CATALO G FOR DETAILS

CONSULT

Figure 5. Metallizati

CIRCUIT DESCRIPTION

on Diagram

1

e AD590 uses a fundamental property of the silicon

nsistors from which it is made to realize its temperature

tra
proportional characteristic: if two identical transis
operated at a constant ratio of col
then the difference in their base-emit
Because both k (Boltzman’s constant) an

on) are constant, the resulting voltage is directly

electr
proportional to absol

ute temperature (PTAT).

lector current densities, r,

ter voltage is (kT/q)(In r).

d q (the charge of an

tors are

In the AD590, this PTAT voltage is converted to a PTAT current
by low tempe
current of the d

rature coefficient thin-film resistors. e total

evice is then forced to be a multiple of this

423

300-33500

298

µ )A

TUO

I

218

0 1 2

3 4

SUPPLY VOLTAGE (V)

+150°C

5°C

+2

–55°C

5 6 30

500-33500

Figure 7. V–I Plot

1

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

Temperature T
Dec. 1976. Understanding

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

the Specifications–AD590.

Page 6 of 16

AD590

(

V

EXPLANATION OF TEMPERATURE SENSOR
SPECIFICATION

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 specificati
supply volta

e AD590 is a PTAT
current is equal to a scale factor times the temperature of the
sensor in degrees Kelvin. is scale factor is trimmed to 1 µ
at the factory, by a
the output current) to agree with the actual temperature. is is
done with 5 V across the device at a temperature within a few
degrees of 25°C (298.2K). 

ted for accuracy over temperature.

tes

ge and thermal environment on accuracy.

S

ons and the effects of the

1

current regulator. at is, the output

djusting the indicated temperature (that is,

e device is then packaged and

A/K

CALIBRATION ERROR

At final factory test, the difference between the indicated
temperature and the actual temperature is called the calibration

or. Since this is a scale factory error, its contribution to the

err
total err
1°C spe
–55°C to 1.
calibration error w

or of the device is PTAT. For example, the effect of the

cified maximum error of the AD590L varies from 0.73°C at

Fig

42°C at 150°C.

ure 8 shows how an exaggerated

ould vary from the ideal over temperature.

+

5

–

Figure 9. One Temperature Trim

100Ω

950Ω

R

+

AD590

–

= 1mV/K

V

T

+

700-33500

–

ERROR VS. TEMPERATURE: WITH CALIBRATION
ERROR TRIMMED OUT

Each AD590 is tested for error over the temperature range with
the calibrati
be called the variance fr
differenc
PTAT multiplication of the actual current at 25°C. is err
co

nsists of a slope error and some curvature, mostly at the
temperature extremes.
tempe

on error trimmed out. is specification could also

om PTAT, because it is the maximum

e between the actual current over temperature and a

or

Figure 10 shows a typical AD590K

rature curve before and aer calibration error trimming.

2

)C°( RORRE ETULOSBA

BEFORE
C

ALIBRATION

TRIM

CALIBRATION

ER

ROR

ACTUAL

ANSFER

TR

FU

NCTION

I

ACTUAL

µ )A

TUO

I

CALIBRATION

ROR

ER

298.2

298.2
ERATURE (°K)

TEMP

Figure 8. Calibration Error vs. Temperature

IDEAL

TR

ANSFER

FU

NCTION

e calibration error is a primary contributor to the maximum
total err
factor err
most elementary way of ac
the tempe
temperature se

or in all AD590 grades. However, because it is a scale

or, it is particularly easy to trim. Figure 9 shows the

complishing this. To trim this circuit,

rature of the AD590 is measured by a reference

nsor 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

nge. In most applications, there is a current-to-voltage

ra
conversion resistor (or, as with a current input ADC, a
reference) that

can be trimmed for scale factor adjustment.

0

AFTER
CALIBRATION
TRIM

–2

600-33500

ERROR VS. TEMPERATURE: NO USER TRIMS

–55 150

Figure 10. Effect to Scale Factor Trim on Accuracy

ERATURE (°C)

TEMP

800-33500

Using the AD590 by simply measuring the current, the total

or is the variance from PTAT, described above, plus the effect

err
of the calibration err

or over temperature. For example, the

AD590L maximum total err

or 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 fr
line. e nonlinearity of the AD590 over the −55°C to +150°C
range is superior to all convent
senso

rs such as thermocouples, RTDs, and thermistors.

shows the non

1

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

lower temperature.

linearity of the typical AD590K from

ional electrical temperature

om a best-fit straight

Fig

ure 11

Fig

ure 10.

Page 7 of 16

AD590

V

R

A

1.6

)C°( RORRE ETULOSBA

0.8

0.8°C MAX

0

50

0.8°C
MAX

900-33500

0.8

–

–1.6

0.8°C
MAX

–

55 1

TEMPERATU

Figure 11. Nonl

RE (°C)

inearity

Figure 12 shows a circuit in which the nonlinearity is the major
contribut

or to error over temperature. e circuit is trimmed
by adjusting R1 for a 0 V output with the AD590 at 0°C. R2 is
the

n adjusted for 10 V output with the sensor at 100°C. Other
pairs of temperatures can be used with this procedure as long as
the

y are measured accurately by a reference sensor. Note that

for 15 V outp

ut (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

ound, there is no voltage applied across the device.

gr

15

R1

2kΩ

AD581

35.7kΩ

27kΩ

V–

Figure 12. 2-Temperature Trim

2

)C°( ERUT

EPMET

0

–2

–

55 0 1

Fig

TEMPERATU

ure 13. Typical 2-Trim Accuracy

97.6kΩ

AD590

R2

5kΩ

30pF

AD707A

RE (°C)

100mV/°C

= 100mV/°C

V

T

010-33500

110-33500

50100

VOLTAGE AND THERMAL ENVIRONMENT EFFECTS

e power supply rejection specifications show the maximum
expected chang
e insensitivity of the output to input voltage allows the use of
unregulated sup
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 cha
thi

s change is equivalent to a calibration error and can be

removed by the s

e AD590 specifications are guaranteed for use in a low
thermal resistance envir
Large change
change the amount of sel
outpu

t, which are predictable but not necessarily desirable.

e therm
determine
heating and the respo
model of the AD590 that demonstrates these characteristics.

As an example, for the TO-52 package, θJC is the thermal

sistance between the chip and the case, about 26°C/W. θ

re
the therma
an

d 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

gives the sum of θ

Table 4
thermal media for both the H and F pac
used was a comm
rise of an AD590 H package in a stirred bath at 25°C, when
dri

ven with a 5 V supply, is 0.06°C. However, for the same

con

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

suppl

y voltage, the temperature rise varies with the current and
is PTAT. ere
sensor in the same thermal envir
scale factor trim compensates for this effect over the entire
temperature range.

e in output current vs. input voltage changes.

plies. It also means that hundreds of ohms of

nge the PTAT nature of the AD590. In other words,

cale factor trim (see

Figure 10).

onment with 5 V across the sensor.

s in the thermal resistance of the sensor’s environment

f-heating and result in changes in the

al environment in which the AD590 is used

s two important characteristics: the effect of self-

nse of the sensor with time. Figure 14 is a

T

?

T

JC

J

P

C

CH

?

CA

C

+

210-33500

T

C

C

A

–

Figure 14. Thermal Circuit Model

CA

l resistance between the case and the surroundings

, above the

J

, is

A

and θCA for several common

JC

kages. e heat sink

on clip-on. Using Equation 1, the temperature

fore, if an application circuit is trimmed with the

onment in which it is used, the

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

instantaneous temperature change.

e time response of the AD590 to a step change in
temperature is determined by the thermal resistances and the
thermal capacit

ies of the chip, C
about 0.04 Ws/°C for the AD590. C
medium, b

ecause it includes anything that is in direct thermal
contact with the case. e singl
curve of
respo
sever

Figure 15 is usually sufficient to describe the time

nse, T (t). Table 4

shows the effective time constant, τ, for

al media.

, and the case, CC. CCH is

CH

varies with the measured

C

e time constant exponential

T

FINAL

ERUTAREPMET DESNES

) × (1 – e

–t/τ

)

310-33500

T

INITIAL

t) = T

T(

τ

INITIAL

+ (T

FINAL

TIME

– T

INITIAL

4

τ

Figure 15. Time Response Curve

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
P

in 2 are gr

ounded; for Fahrenheit temperature, Pin 4 and Pin 2

are le open.

5

OFFSET

9

C

ALIBRATION

GAIN

4

2

ALING

SC

OFFSET
SC

ALING

410-33500

D590

6

+

–

5

Figure 16. Variabl

8

AD2040

3

GND

e Scale Display

e above configuration yields a 3-digit display with 1°C or 1°F

ution, in addition to an absolute accuracy of ±2.0°C over

resol
the −55°C to +125°C temperature r

ange, if a one-temperature

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

cting several AD590 units in series, as shown in Fig

Conne

ure 17,
allows the minimum of all the sensed temperatures to be
in

dicated. In contrast, using the sensors in parallel yields the

average of the sensed temperatures.

15

+

10kΩ

0.1%)

AD590

–
+

AD590

–
+

AD590

–

+

MIN

V

T

–

+

–

333.3Ω
(0.1%)

5V

+

+

AD590

–

–

+

AVG

V

T

510-33500

–

Figure 17. Series and Parallel Connection

e circuit in Figure 18 demonstrates one method by which
differentia
can be used to tri

l temperature measurements can be made. R1 and R2

m the output of the op amp to indicate a

desired temperature difference. For example, the inherent offset

en the two devices can be trimmed in. If V+ and V− are

betwe
radically different

, then the difference in internal dissipation
causes a differential internal temperature rise. is effect can be
used to measu
sensors in ap

re the ambient thermal resistance seen by the

plications 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 tempera
as the thermoc

en 15°C and 35°C. e circuit is calibrated by adjusting R

betwe

oper meter reading with the measuring junction at a

for a pr
kn

own reference temperature and the circuit near 25°C. Using

nents with the TCs as specified in Fig

compo
accuracy is within ±0.5°C for circuit temperatures
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 resis

7.5

AD580

+

V

OUT

–

ure 19. Cold Junction Compensation Circuit for Type J Thermocouple

Fig

V

R3

1

0kΩ

–

R1
5MΩ

V–

5

0kΩ

R2

Figure 18. Differe

10kΩ

AD707A

(T1 – T2) × (10mV/°C)

+

R4

ntial Measurements

ture. is circuit replaces an ice-bath

ouple reference for ambient temperatures

ure 19, compensation

between

tors are the primary contributors to error.

IRON

CONSTANTAN

+

–

MEASU

RING

–

JUNCTION

AD590

52.3Ω

8.6

6kΩ

1kΩ

+

–

R

T

REFERENCE
JUNCTI

ON

C

METER

RE

U

+

SISTORS ARE 1%, 50ppm/°C

610-33500

T

710-33500

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 fu

ll current range of 4
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
at an intermediate reference temperature. With a suita

is trimmed for proper reading

T

ble 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

–

+

–

10kΩ

ure 20. 4 to 20 mA Current Transmitter

Fig

35.7kΩ

5kΩ

12.7kΩ

10Ω

R

T

–

AD707A

+

V–

30pF

5kΩ 500Ω

810-33500

Figure 21 is an example of a variable temperature control circuit
(thermostat) using the AD590. R
high and low limit
calibrated multi
the AD590 fr
suppl

y variations while maintaining a reasonable voltage (~7 V)

s for R

SET

turn pot, or a switched resistive divider. Powering

om the 10 V reference isolates the AD590 from

across it. Capacitor C1 is oen needed to filter extraneous
fr

om remote sensors. R

trans

istor and the current requirements of the load.

AD581

V+

OUT

V–

1

R

H

AD590

R

SET

R

L

Figure 21. Sim

is determined by the β of the power

B

0V

+

–

C1

1

ple Temperature Control Circuit

and RL are selected to set the

H

. R

could be a simple pot, a

SET

+

R

B

7

2

–

LM311

3

0kΩ

1

+

4

GND

noise

HEATING
ELEMENTS

910-33500

20p

1.2

5kΩ

1kΩ

OUTPUT HIGH­TEMP

7

OUTPUT LOW­TEMP

5.1MΩ

REF

+5V

1.15kΩ

200Ω, 15T

+5V

+2.5V

200Ω

ERATURE ABOVE SETPOINT

ERATURE BELOW SETPOINT

AD580

020-33500

–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

3

2

6.8kΩ

14

LM311

–15V

MC

08/1508

+5V +5V

8

1

4

Figure 22. DAC Setpoint

e voltage compliance and the reverse blocking characteristic
of the AD590 allow it to be powered directly from 5 V CMOS
logic. is permits easy multiplexing, swi
minimum int
connected to a logic high passe
current measuring circuitry,
zero pass ins

ernal heat dissipation. In Figure 23, any AD590

s a signal current through the

while those connected to a logic

ignificant current. e outputs used to drive the

tching, or pulsing for

AD590s can be employed for other purposes, but the additional
capacitance due to

the AD590 should be taken into account.

5

+

D590

CMOS

GATES

+

–

+

–

Figure 23. AD590 Driven from CMOS Logic

–

+

–

1kΩ (0.1%)

120-3350

Figure 22 shows that the AD590 can be configured with an 8-bit
DAC to produce a digitally controlled setpoint. is particular
circuit operates fr
low) in 0.2°C steps. 

teresis, which is usually necessary to guard-band for extraneous

hys

om 0°C (all inputs high) to 51.0°C (all inputs

e comparator is shown with 1.0°C

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

uch switche

s
across the transdu
the principle demonstrated in Figure 23 with an 8-chann
CMOS multiplexer. 
sensors over only 18 wires with a 7-b

s is unimportant as long as 4 V is maintained

cer. Figure 24 shows a circuit that combines

e resulting circuit can select 1 to 80

it binary word.

10

16

3

14

2

4028

CMOS

B

CD-TO-

DECIMAL

DECODER

11

ROW

S

ELECT

12
13
10

8

el

0
1
2

+

–

22

e inhibit input on the multiplexer turns all sensors off for
m

inimum dis

sipation while idling.

Figure 25 demonstrates a method of multiplexing the AD590 in

rim mode (see Fig

the 2-t

d their associated resistors can be added to multiplex up to

an
eight c

hannels of ±0.5°C absolute accuracy over the temperature

ure 12 and Figure 13). Additional AD590s

range of −55°C to +125°C. e high temperature restriction of
125°C is due to the output r
150°C can be achieved by using a 20 V su

+

+

–

+

–

02

12

–

+

+

–

21

+

–

01

11

–

20

ange of the op amps; output to

pply for the op amp.

+

+

AD590

–

00

–

10

COLUMN

S

ELECT

HIBIT

IN

AD581

+15V

+

–

9

10

11

6

10V

16

LOGIC
LEV

INTERFA

7 8

EL

CE

BINARY TO 1-OF-8 DECODER

0131142

15

4

051 CMOS ANALOG

MULTIPLE

10kΩ 10mV/°C

XER

220-33500

Figure 24. Matr

2kΩ

35.7kΩ

2kΩ

35.7kΩ

V

OUT

S1

S2

S8

+15V

–15V

ix Multiplexer

5kΩ

97.6kΩ

5kΩ

97.6kΩ

AD7501

TTL/DTL TO CMOS

INTERFA

DECODER/

DRIVER

CE

AD707A

27kΩ

V+

10mV/°C

–15V

+

+

AD590L

–5V TO –15V

–

AD590L

–

Figure 25. 8

EN

BINARY

CHANNEL

SELECT

-Channel Multiplexer

320-33500

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)

0.500 (12.69)

0.0065 (0.17)

0.0050 (0.13)

0.0045 (0.12)

Figure 2

Dimen

TYP

MIN

6. 2-Lead Ceramic Flat Package [CQFP]

sions 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)

4.8

0 (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

)25.4( 871.0

)48.5( 032.0

)13.5( 902.0

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.

Figure 2

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.

7. 3-Pin Metal Header Package [TO-52]

45° T.P.

0.048 (1.22)

0.028 (0.71)

0.046 (1.17)

0.036 (0.91)

3

1

(H-03)

sions shown in inches and (millimeters)

Dimen

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

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

Narrow Body

(

imen

D

sions shown in millimeters and (inches)

R-8)

× 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 Service
Department will issue an Authorized Return (AR) number immediately upon phone or written request.
Upon examination by OMEGA, if the unit is found to be defective, it will be repaired or replaced at no
charge. OMEGA’s WARRANTY does not 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, or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of
having been tampered with or shows evidence of having been damaged as a result of excessive corrosion;
or current, 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 KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF
TITLE, AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY
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
component upon which liability is based. In no event shall OMEGA be liable 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 application, used on humans, or misused in any way, OMEGA assumes no responsibility
as set forth in our basic WARRANTY/DISCLAIMER language, and, additionally, purchaser will indemnify
OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the
Product(s) in such a manner.

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 RETURN (AR)
NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID PROCESSING
DELAYS). The assigned AR number should then be marked on the outside of the return package and on any
correspondence.

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

FOR WARRANTY RETURNS, please have the
following information available BEFORE contacting
OMEGA:

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

2. Model and serial number of the product under
warranty, and

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 2017 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 the prior
written consent of OMEGA ENGINEERING, INC.

FOR NON-WARRANTY REPAIRS, consult
OMEGA for current repair charges. Have
the following information available BEFORE
contacting OMEGA:

1. Purchase Order number to cover the COST
of the repair,

2. Model and serial number of the product, and

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

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Process Measurement and Control?

OMEGA…Of Course!

Shop online at omega.com

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