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National Semiconductor - LM34 Precision Fahrenheit Temperature Sensors User Guide

Summary

The LM34 series is a high-precision integrated circuit temperature sensor designed specifically for accurate Fahrenheit measurement. Offering linear output directly calibrated in °F, it eliminates the need for complex Kelvin conversions. This technical guide provides comprehensive documentation covering electrical characteristics, accuracy specifications, multiple packages (TO-46, TO-92, SO-8), and detailed application parameters for engineers designing industrial or remote temperature monitoring systems requiring reliable performance from -50°F to +300°F.

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Page 1 Text Content

November

LM recision Fahrenheit Tem perature ensors

LM34 Precision Fahrenheit Temperature Sensors

hermetic TO-46 transistor packages, while the LM34C,

General Description

LM34CA and LM34D are also available in the plastic TO-92

The LM34 series are precision integrated-circuit temperature

transistor package. The LM34D is also available in an 8-lead

sensors, whose output voltage is linearly proportional to the

surface mount small outline package. The LM34 is comple-

Fahrenheit temperature. The LM34 thus has an advantage

ment to the LM35 (Centigrade) temperature sensor.

over linear temperature sensors calibrated in degrees Kelvin, as the user is not required to subtract large con-

Features

stant voltage from its output to obtain convenient Fahrenheit

scaling. The LM34 does not require any external calibration Calibrated directly in degrees Fahrenheit or trimming to provide typical accuracies of ±1⁄2˚F at room Linear +10.0 m V/˚F scale factor

temperature and ±11⁄2˚F over full −50 to +300˚F tempera- 1.0˚F accuracy guaranteed (at +77˚F)

ture range. Low cost is assured by trimming and calibration Rated for full −50˚ to +300˚F range at the wafer level. The LM34’s low output impedance, linear

Suitable for remote applications

output, and precise inherent calibration make interfacing to

Low cost due to wafer-level trimming

readout or control circuitry especially easy. It can be used

Operates from to volts

with single power supplies or with plus and minus supplies.

Less than µA current drain

As it draws only µA from its supply, it has very low

Low self-heating, 0.18˚F in still air

self-heating, less than 0.2˚F in still air. The LM34 is rated to

operate over −50˚ to +300˚F temperature range, while the Nonlinearity only ±0.5˚F typical

LM34C is rated for −40˚ to +230˚F range (0˚F with im- Low-impedance output, 0.4Ω for m A load proved accuracy). The LM34 series is available packaged in

Connection Diagrams

TO-46

Metal Can Package TO-92

(Note 1) Plastic Package

Small Outline Molded Package

DS006685-1 DS006685-2

Order Numbers LM34H, Order Number LM34CZ, LM34AH, LM34CH, LM34CAZ or LM34DZ

DS006685-20

LM34CAH or LM34DH See NS Package

N.C. No Connection

See NS Package Number Z03A Number H03H View

Order Number LM34DM See NS Package Number M08A

Note 1: Case is connected to negative pin (GND).

National Semiconductor Corporation DS006685 www.national.com

Page Summary Contents For National Semiconductor - LM34 Precision Fahrenheit Temperature Sensors User Guide

Page 1 November LM recision Fahrenheit Tem perature ensors LM34 Precision Fahrenheit Temperature Sensors hermetic TO-46 transistor packages, while the LM34C, General Description LM34CA and LM34D are also ava...
Page 2 Typical Applications DS006685-3 FIGURE 1. Basic Fahrenheit Temperature Sensor (+5˚ to +300˚F) DS006685-4 FIGURE 2. Full-Range Fahrenheit Temperature Sensor www.national.com
Page 3 Absolute Maximum Ratings (Note 11) TO-46 Package LM (Soldering, seconds) +300˚C If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ TO-92 Pack...
Page 4 DC Electrical Characteristics (Notes 2, 7) (Continued) Note 8: Accuracy is defined as the error between the output voltage and m V/˚F times the device’s case temperature at specified conditions of vol...
Page 5 Typical Performance Characteristics LM Thermal Resistance Thermal Time Constant Thermal Response in Junction to Air Still Air DS006685-23 DS006685-22 DS006685-24 Thermal Response in Minimum Supply Vol...
Page 6 Typical Performance Characteristics (Continued) Noise Voltage Start-Up Response DS006685-31 DS006685-32 These devices are sometimes soldered to small, Typical Applications light-weight heat fin to dec...
Page 7 Typical Applications LM DS006685-7 FIGURE 3. LM34 with Decoupling from Capacitive Load DS006685-8 FIGURE 4. LM34 with R-C Damper Temperature Rise of LM34 Due to Self-Heating (Thermal Resistance) Condi...
Page 8 Typical Applications (Continued) 4-to-20 m A Current Source Fahrenheit Thermometer (0 to +100˚F) (Analog Meter) DS006685-12 DS006685-11 Expanded Scale Thermometer Temperature-to-Digital Converter (50˚...
Page 9 Typical Applications (Continued) LM Bar-Graph Temperature Display (Dot Mode) DS006685-16 1% or 2% film resistor Trim RB for VB 3.525V Trim RC for VC 2.725V Trim RA for VA 0.085V m V/˚F TAMBIENT Exampl...
Page 10 Typical Applications (Continued) Temperature Controller DS006685-18 Block Diagram DS006685-19 www.national.com
Page 11 Physical Dimensions inches (millimeters) unless otherwise noted LM Order Number LM34H, LM34AH, LM34CH, LM34CAH or LM34DH NS Package H03H Order Number LM34DM NS Package Number M08A www.national.com11
Page 12 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) LM re ci si on Fa hr en he it Te pe ra tu re en so rs Order Number LM34CZ, LM34CAZ or LM34DZ NS Package Z03A LIFE SUPPORT PO...

Manual Details

Brand National
Pages 12
File Size 251.21 KB
Published July 16, 2026
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Frequently Asked Questions

What is the temperature range for the different LM34 packages?

The LM34A/LM34 supports -50˚F to +300˚F; LM34C/LM34CA supports -40˚F to +230˚F; and LM34D supports +32˚F to +212˚F.

Does the LM34 require external calibration?

No, the LM34 does not require any external calibration or trimming for accurate use in Fahrenheit units.

What kind of power supply voltage can the LM34 operate from?

It operates from 5 to 30 volts, compatible with both single and dual power supplies (plus/minus).