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TL/H/5698

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

February 1995

LM135/LM235/LM335, LM135A/LM235A/LM335A

Precision Temperature Sensors

General Description

The LM135 series are precision, easily-calibrated, integrat-

ed circuit temperature sensors. Operating as a 2-terminal

zener, the LM135 has a breakdown voltage directly propor-

tional to absolute temperature at

10 mV/

K. With less

than 1X dynamic impedance the device operates over a

current range of 400 mA to 5 mA with virtually no change in

performance. When calibrated at 25

C the LM135 has typi-

cally 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 tem-

perature sensing over a

Cto

150

C temperature

range. The low impedance and linear output make interfac-

ing to readout or control circuitry especially easy.

The LM135 operates over a

Cto

150

C temperature

range while the LM235 operates over a

Cto

125

temperature range. The LM335 operates from

Cto

100

C. The LM135/LM235/LM335 are available pack-

aged in hermetic TO-46 transistor packages while the

LM335 is also available in plastic TO-92 packages.

Features

Directly calibrated in

Kelvin

C initial accuracy available

Operates from 400 mAto5mA

Less than 1X dynamic impedance

Easily calibrated

Wide operating temperature range

200

C overrange

Low cost

Schematic Diagram

TL/H/5698–1

Connection Diagrams

TO-92

Plastic Package

TL/H/5698–8

Bottom View

Order Number LM335Z or LM335AZ

See NS Package Number Z03A

SO-8

Surface Mount Package

TL/H/5698–25

Order Number LM335M or

LM335AM

See NS Package Number M08A

TO-46

Metal Can Package*

TL/H/5698–26

Bottom View

*Case is connected to negative pin

Order Number LM135H,

LM135H-MIL, LM235H, LM335H,

LM135AH, LM235AH or LM335AH

See NS Package Number H03H

1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

Summary of content (12 pages)

PAGE 1
LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors General Description The LM135 series are precision, easily-calibrated, integrated circuit temperature sensors. Operating as a 2-terminal zener, the LM135 has a breakdown voltage directly proportional to absolute temperature at a 10 mV/§ K. With less than 1X dynamic impedance the device operates over a current range of 400 mA to 5 mA with virtually no change in performance.
PAGE 2
Absolute Maximum Ratings Specified Operating Temp. Range If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications.
PAGE 3
Typical Performance Characteristics Reverse Voltage Change Calibrated Error Reverse Characteristics Response Time Dynamic Impedance Noise Voltage Thermal Resistance Junction to Air Thermal Time Constant Thermal Response in Still Air Thermal Response in Stirred Oil Bath Forward Characteristics TL/H/5698 – 3 3
PAGE 4
Application Hints 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 drive both the sensor and the calibration pot at the maximum operating temperature as well as any external loads.
PAGE 5
Typical Applications (Continued) Isolated Temperature Sensor TL/H/5698 – 20 Simple Temperature Controller TL/H/5698 – 5 Simple Temperature Control TL/H/5698 – 21 5
PAGE 6
Typical Applications (Continued) Centigrade Thermometer Ground Referred Fahrenheit Thermometer TL/H/5698–22 *Adjust R2 for 2.554V across LM336. TL/H/5698 – 23 Adjust R1 for correct output. *Adjust for 2.7315V at output of LM308 Fahrenheit Thermometer TL/H/5698 – 24 *To calibrate adjust R2 for 2.554V across LM336. Adjust R1 for correct output.
PAGE 7
Typical Applications (Continued) Single Power Supply Cold Junction Compensation *Select R3 and R4 for thermocouple type THERMOR3 R4 COUPLE J 1.05K 385X T 856X 315X K 816X 300X S 128X 46.3X SEEBECK COEFFICIENT 52.3 mV/§ C 42.8 mV/§ C 40.8 mV/§ C 6.4 mV/§ 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 T K S 14.32 mV 11.79 mV 11.17 mV 1.
PAGE 8
Typical Applications (Continued) Differential Temperature Sensor TL/H/5698 – 14 Variable Offset Thermometer ³ ² 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 ³ Output reads difference between temperature and dial setting of 10T pot TL/H/5698 – 15 8
PAGE 9
Typical Applications (Continued) Ground Referred Centigrade Thermometer Air Flow Detector* TL/H/5698 – 17 *Self heating is used to detect air flow TL/H/5698 – 16 Definition of Terms Calibrated Temperature Error: The error between operating output voltage and case temperature at 10 mV/§ K over a temperature range at a specified operating current with the 25§ C error adjusted to zero.
PAGE 10
PAGE 11
Physical Dimensions inches (millimeters) Metal Can Package (H) Order Number LM135H, LM235H, LM335H, LM135AH, LM235AH or LM335AH NS Package Number H03H 8-Lead Molded Small Outline Package (M) Order Number LM335M or LM335AM NS Package Number M08A 11
PAGE 12
LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors Physical Dimensions inches (millimeters) (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 OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1.