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