Rainbow Electronics LM335A User Manual

LM135/LM235/LM335, LM135A/LM235A/LM335A
Precision Temperature Sensors

LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors

November 2000

General Description

The LM135 series are precision, easily-calibrated, integrated
circuit temperature sensors.Operatingasa2-terminalzener,
the LM135 has a breakdown voltage directly proportional to
absolute temperature at +10 mV/˚K. With less than 1Ω dy­namic impedance the device operates over a current range
of 400 µA to 5 mA with virtually no change in performance.
When calibrated at 25˚C the LM135 has typically less than
1˚C error over a 100˚C temperature range. Unlike other
sensors the LM135 has a linear output.

Applications for the LM135 include almost any type of tem­perature sensing over a −55˚C to +150˚C temperature
range. The low impedance and linear output make interfac­ing to readout or control circuitry especially easy.

The LM135 operates over a −55˚C to +150˚C temperature
range while the LM235 operates over a −40˚C to +125˚C

Schematic Diagram

temperature range. The LM335 operates from −40˚C to
+100˚C. The LM135/LM235/LM335 are available packaged
in hermetic TO-46 transistor packages while the LM335 is
also available in plastic TO-92 packages.

Features

n Directly calibrated in ˚Kelvin
n 1˚C initial accuracy available
n Operates from 400 µA to 5 mA
n Less than 1Ω dynamic impedance
n Easily calibrated
n Wide operating temperature range
n 200˚C overrange
n Low cost

DS005698-1

© 2000 National Semiconductor Corporation DS005698 www.national.com

Connection Diagrams

TO-92

Plastic Package

DS005698-8

Bottom View

Order Number LM335Z

or LM335AZ

See NS Package

Number Z03A

LM135/LM235/LM335, LM135A/LM235A/LM335A

SO-8

Surface Mount Package

DS005698-25

Order Number LM335M

See NS Package

Number M08A

TO-46

Metal Can Package*

DS005698-26

*Case is connected to negative pin

Bottom View

Order Number LM135H,

LM135H-MIL, LM235H,

LM335H, LM135AH,

LM235AH or LM335AH

See NS Package

Number H03H

www.national.com 2

Absolute Maximum Ratings (Note 4)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Reverse Current 15 mA
Forward Current 10 mA
Storage Temperature

TO-46 Package −60˚C to +180˚C
TO-92 Package −60˚C to +150˚C
SO-8 Package −65˚C to +150˚C

Temperature Accuracy (Note 1)

LM135/LM235, LM135A/LM235A

Parameter Conditions LM135A/LM235A LM135/LM235 Units

Operating Output Voltage T
Uncalibrated Temperature Error T
Uncalibrated Temperature Error T
Temperature Error with 25˚C T
Calibration
Calibrated Error at Extended T
Temperatures
Non-Linearity I

= 25˚C, IR= 1 mA 2.97 2.98 2.99 2.95 2.98 3.01 V

C

= 25˚C, IR= 1 mA 0.5 1 1 3 ˚C

C

≤ TC≤ T

MIN

≤ TC≤ T

MIN

C=TMAX

= 1 mA 0.3 0.5 0.3 1 ˚C

R

MAX,IR
MAX,IR

(Intermittent) 2 2 ˚C

LM135/LM235/LM335, LM135A/LM235A/LM335A

Specified Operating Temp. Range

Continuous Intermittent

(Note 2)
LM135, LM135A −55˚C to +150˚C 150˚C to 200˚C
LM235, LM235A −40˚C to +125˚C 125˚C to 150˚C
LM335, LM335A −40˚C to +100˚C 100˚C to 125˚C
Lead Temp. (Soldering, 10 seconds)

TO-92 Package: 260˚C
TO-46 Package: 300˚C
SO-8 Package: 300˚C

Vapor Phase (60 seconds): 215˚C
Infrared (15 seconds): 220˚C

Min Typ Max Min Typ Max

= 1 mA 1.3 2.7 2 5 ˚C
= 1 mA 0.3 1 0.5 1.5 ˚C

Temperature Accuracy (Note 1)

LM335, LM335A

Parameter Conditions LM335A LM335 Units

Min Typ Max Min Typ Max

Operating Output Voltage T
Uncalibrated Temperature Error T
Uncalibrated Temperature Error T
Temperature Error with 25˚C T

= 25˚C, IR= 1 mA 2.95 2.98 3.01 2.92 2.98 3.04 V

C

= 25˚C, IR=1mA 13 26˚C

C
MIN
MIN

≤ TC≤ T
≤ TC≤ T

=1mA 25 49˚C

MAX,IR

= 1 mA 0.5 1 1 2 ˚C

MAX,IR

Calibration
Calibrated Error at Extended T

C=TMAX

(Intermittent) 2 2 ˚C
Temperatures
Non-Linearity I

= 1 mA 0.3 1.5 0.3 1.5 ˚C

R

Electrical Characteristics (Note 1)

LM135/LM235 LM335

Parameter Conditions LM135A/LM235A LM335A Units

Min Typ Max Min Typ Max

Operating Output Voltage 400 µA≤I
Change with Current At Constant Temperature
Dynamic Impedance I

=1 mA 0.5 0.6 Ω

R

Output Voltage Temperature +10 +10 mV/˚C
Coefficient
Time Constant Still Air 80 80 sec

100 ft/Min Air 10 10 sec
Stirred Oil 1 1 sec

Time Stability T

C

≤5 mA 2.5 10 3 14 mV

R

=125˚C 0.2 0.2 ˚C/khr

www.national.com3

Electrical Characteristics (Note 1) (Continued)

Note 1: Accuracy measurements are made in a well-stirred oil bath. For other conditions, self heating must be considered.
Note 2: Continuous operation at these temperatures for 10,000 hours for H package and 5,000 hours for Z package may decrease life expectancy of the device.
Note 3:

Thermal Resistance TO-92 TO-46 SO-8

θ

(junction to ambient) 202˚C/W 400˚C/W 165˚C/W

JA

θ

(junction to case) 170˚C/W N/A N/A

JC

Note 4: Refer to RETS135H for military specifications.

Typical Performance Characteristics

Reverse Voltage Change

LM135/LM235/LM335, LM135A/LM235A/LM335A

Response Time

DS005698-27

Calibrated Error

Dynamic Impedance

DS005698-28

Reverse Characteristics

DS005698-29

Noise Voltage

DS005698-30

Thermal Resistance

Thermal Time Constant

Junction to Air

DS005698-33

www.national.com 4

DS005698-31

DS005698-34

DS005698-32

Thermal Response in Still Air

DS005698-35

Typical Performance Characteristics (Continued)

LM135/LM235/LM335, LM135A/LM235A/LM335A

Thermal Response in Stirred Oil Bath

DS005698-36

Application Hints

CALIBRATING THE LM135

Included on the LM135chip is an easy methodof calibrating
the device for higher accuracies.A pot connectedacross the
LM135 with the arm tied to the adjustment terminal allows a
1-point calibration of the sensor that corrects for inaccuracy
over the full temperature range.

This single point calibration works because the output of the
LM135 is proportional to absolute temperature with the ex­trapolated output of sensor going to 0V output at 0˚K
(−273.15˚C). Errors in output voltage versus temperature are
only slope (or scale factor) errors so a slope calibration at
one temperature corrects at all temperatures.

The output of the device (calibrated or uncalibrated) can be
expressed as:

where T is the unknown temperature and Tois a reference
temperature, both expressed in degrees Kelvin. By calibrat­ing the output to read correctly at one temperature the output
at all temperatures is correct. Nominally the output is cali­brated at 10 mV/˚K.

Forward Characteristics

DS005698-37

To insure good sensing accuracy several precautions must
be taken. Like any temperature sensing device, self heating
can reduce accuracy. The LM135 should be operated at the
lowest current suitable for the application. Sufficient current,
of course, must be available to driveboth the sensor andthe
calibration pot at the maximum operating temperature as
well as any external loads.

If the sensor is used in an ambient where the thermal resis­tance is constant, self heating errors can be calibrated out.
This is possible if the device isrun witha temperature stable
current. Heating will then be proportional to zener voltage
and therefore temperature. This makes the selfheating error
proportional to absolute temperature the same as scale
factor errors.

WATERPROOFING SENSORS

Meltable inner core heat shrinkable tubing suchas manufac­tured by Raychem canbe usedto makelow-cost waterproof
sensors. The LM335 is inserted into the tubing about
from the end and the tubing heated above the melting point
of the core. The unfilled

1

⁄2" end melts and provides a seal

over the device.

1

⁄2"

Typical Applications

Basic Temperature Sensor

DS005698-2

Calibrated Sensor

*Calibrate for 2.982V at 25˚C

Wide Operating Supply

DS005698-9

DS005698-10

www.national.com5

Typical Applications (Continued)

Minimum Temperature Sensing

LM135/LM235/LM335, LM135A/LM235A/LM335A

DS005698-4

Average Temperature Sensing

DS005698-18

Remote Temperature Sensing

DS005698-19

Wire length for 1˚C error due to wire drop

IR=1

IR= 0.5 mA

mA

AWG FEET FEET

14 4000 8000
16 2500 5000
18 1600 3200
20 1000 2000
22 625 1250
24 400 800

*

For IR= 0.5 mA, the trim pot must be deleted.

*

Isolated Temperature Sensor

DS005698-20

www.national.com 6

Typical Applications (Continued)

LM135/LM235/LM335, LM135A/LM235A/LM335A

Simple Temperature Controller

DS005698-5

Simple Temperature Control

Ground Referred Fahrenheit Thermometer

*Adjust R2 for 2.554V across LM336.
Adjust R1 for correct output.

DS005698-22

DS005698-21

Centigrade Thermometer

DS005698-23

*Adjust for 2.7315V at output of LM308

www.national.com7

Typical Applications (Continued)

*To calibrate adjust R2 for 2.554V across LM336.
Adjust R1 for correct output.

Fahrenheit Thermometer

DS005698-24

LM135/LM235/LM335, LM135A/LM235A/LM335A

*

Select R3 for proper thermocouple type

THERMOCOUPLE COLD JUNCTION COMPENSATION

Compensation for Grounded Thermocouple

DS005698-6

THERMO- R3 SEEBECK

COUPLE (

±

1%) COEFFICIENT

J 377Ω 52.3 µV/˚C

T 308Ω 42.8 µV/˚C
K 293Ω 40.8 µV/˚C
S 45.8Ω 6.4 µV/˚C

Adjustments: Compensates for both sensor and resistor tolerances

1. Short LM329B

2. Adjust R1 for Seebeck Coefficient times ambient temperature (in degrees K) across R3.

3. Short LM335 and adjust R2 for voltage across R3 corresponding to thermocouple type

J 14.32 mV K 11.17 mV
T 11.79 mV S 1.768 mV

www.national.com 8

Typical Applications (Continued)

Single Power Supply Cold Junction Compensation

LM135/LM235/LM335, LM135A/LM235A/LM335A

*

Select R3 and R4 for thermocouple type

DS005698-11

THERMO- R3 R4 SEEBECK

COUPLE COEFFICIENT

J 1.05K 385Ω 52.3 µV/˚C
T 856Ω 315Ω 42.8 µV/˚C
K 816Ω 300Ω 40.8 µV/˚C
S 128Ω 46.3Ω 6.4 µV/˚C

Adjustments:

1. Adjust R1 for the voltage across R3 equal to the Seebeck Coefficient times ambient temperature in degrees Kelvin.

2. Adjust R2 for voltage across R4 corresponding to thermocouple

J 14.32 mV
T 11.79 mV
K 11.17 mV
S 1.768 mV

www.national.com9

Typical Applications (Continued)

Centigrade Calibrated Thermocouple Thermometer

LM135/LM235/LM335, LM135A/LM235A/LM335A

Terminate thermocouple reference junction in close proximity to LM335.

Adjustments:

1. Apply signal in place of thermocouple and adjust R3 for a gain of 245.7.

2. Short non-inverting input of LM308Aand output of LM329B to ground.

3. Adjust R1 so that V

4. Remove short across LM329B and adjust R2 so that V

5. Remove short across thermocouple.

= 2.982V@25˚C.

OUT

Fast Charger for Nickel-Cadmium Batteries

= 246 mV@25˚C.

OUT

DS005698-12

Differential Temperature Sensor

DS005698-7

†

Adjust D1 to 50 mV greater VZthan D2.

Charge terminates on 5˚C temperature rise. Couple D2 to battery.

www.national.com 10

DS005698-13

Typical Applications (Continued)

LM135/LM235/LM335, LM135A/LM235A/LM335A

Differential Temperature Sensor

DS005698-14

Variable Offset Thermometer

†

Adjust for zero with sensor at 0˚C and 10T pot set at 0˚C

*Adjust for zero output with 10T pot set at 100˚C and sensor at 100˚C

Output reads difference between temperature and dial setting of 10T pot

DS005698-15

www.national.com11

Typical Applications (Continued)

Ground Referred Centigrade Thermometer

LM135/LM235/LM335, LM135A/LM235A/LM335A

Definition of Terms

Operating Output Voltage: The voltage appearing across

the positive and negative terminalsof the device at specified
conditions of operating temperature and current.

Uncalibrated Temperature Error: The error between the
operating output voltage at 10 mV/˚K and case temperature
at specified conditions of current and case temperature.

DS005698-16

Air Flow Detector

*Self heating is used to detect air flow

Calibrated Temperature Error: The error between operat­ing output voltageand case temperature at 10 mV/˚K over a
temperature range at a specified operating current with the
25˚C error adjusted to zero.

*

DS005698-17

www.national.com 12

Physical Dimensions inches (millimeters) unless otherwise noted

Metal Can Package (H)

Order Number LM135H, LM235H, LM335H, LM135AH, LM235AH or LM335AH

NS Package Number H03H

LM135/LM235/LM335, LM135A/LM235A/LM335A

8-Lead Molded Small Outline Package (M)

Order Number LM335M

NS Package Number M08A

www.national.com13

Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

Plastic Package

Order Number LM335Z or LM335AZ

NS Package Z03A

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or

LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors

systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the

2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.

labeling, can be reasonably expected to result in a
significant injury to the user.

National Semiconductor
Corporation

Americas
Tel: [phone]
Fax: [phone]
Email: [e-mail]

www.national.com

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.

National Semiconductor
Europe

Fax: [phone]

Email: [e-mail]
Deutsch Tel: [phone]
English Tel: [phone]
Français Tel: [phone]

National Semiconductor
Asia Pacific Customer
Response Group

Tel: [phone]
Fax: [phone]
Email: [e-mail]

National Semiconductor
Japan Ltd.

Tel: [phone]
Fax: [phone]