文档库 最新最全的文档下载
当前位置:文档库 › LM50CIM3中文资料

LM50CIM3中文资料

LM50CIM3中文资料
LM50CIM3中文资料

LM50

SOT-23Single-Supply Centigrade Temperature Sensor

General Description

The LM50is a precision integrated-circuit temperature sen-sor that can sense a ?40?C to +125?C temperature range us-ing a single positive supply.The LM50’s output voltage is lin-early proportional to Celsius (Centigrade)temperature (+10mV/?C)and has a DC offset of +500mV.The offset al-lows reading negative temperatures without the need for a negative supply.The ideal output voltage of the LM50ranges from +100mV to +1.75V for a ?40?C to +125?C temperature range.The LM50does not require any external calibration or trimming to provide accuracies of ±3?C at room temperature and ±4?C over the full ?40?C to +125?C temperature range.Trimming and calibration of the LM50at the wafer level as-sure low cost and high accuracy.The LM50’s linear output,+500mV offset,and factory calibration simplify circuitry re-quired in a single supply environment where reading nega-tive temperatures is required.Because the LM50’s quiescent current is less than 130μA,self-heating is limited to a very low 0.2?C in still air.

Applications

n Computers n Disk Drives

n Battery Management n Automotive n FAX Machines n Printers

n Portable Medical Instruments n HVAC

n

Power Supply Modules

Features

n Calibrated directly in degree Celsius (Centigrade)n Linear +10.0mV/?C scale factor n ±2?C accuracy guaranteed at +25?C n Specified for full ?40?to +125?C range n Suitable for remote applications

n Low cost due to wafer-level trimming n Operates from 4.5V to 10V n Less than 130μA current drain

n Low self-heating,less than 0.2?C in still air n

Nonlinearity less than 0.8?C over temp

Connection Diagram

Order SOT-23Supplied As Number Device Marking

LM50BIM3T5B 1000Units on Tape and Reel

LM50CIM3

T5C 1000Units on Tape and Reel

LM50BIM3X T5B 3000Units on Tape and Reel

LM50CIM3X

T5C

3000Units on Tape and Reel

Typical Application

SOT-23

DS012030-1

Top View

See NS Package Number MA03B

DS012030-3

FIGURE 1.Full-Range Centigrade Temperature Sensor (?40?C to +125?C)

July 1999

LM50SOT-23Single-Supply Centigrade Temperature Sensor

?1999National Semiconductor Corporation https://www.wendangku.net/doc/1a13726101.html,

Absolute Maximum Ratings(Note1)

Supply Voltage+12V to?0.2V Output Voltage(+V S+0.6V)to?1.0V Output Current10mA Storage Temperature?65?C to+150?C Lead Temperature:

SOT Package(Note2):

Vapor Phase(60seconds)215?C Infrared(15seconds)220?C T JMAX,Maximum

Junction Temperature150?C ESD Susceptibility(Note3):

Human Body Model

Machine Model

2000V

250V Operating Ratings(Note1)

Specified Temperature Range:T MIN to T MAX LM50C?40?C to+125?C LM50B?25?C to+100?C Operating Temperature Range?40?C to+150?C θJA(Note4)450?C/W Supply Voltage Range(+V S)+4.5V to+10V

Electrical Characteristics

Unless otherwise noted,these specifications apply for V S=+5V DC and I LOAD=+0.5μA,in the circuit of Figure1.Boldface limits apply for the specified T A=T J=T MIN to T MAX;all other limits T A=T J=+25?C,unless otherwise noted.

Parameter Conditions LM50B LM50C Units

(Limit)

Typical Limit Typical Limit

(Note5)(Note5)

Accuracy T A=+25?C±2.0±3.0?C(max) (Note6)T A=T MAX±3.0±4.0?C(max)

T A=T MIN+3.0,?3.5±4.0?C(max) Nonlinearity(Note7)±0.8±0.8?C(max) Sensor Gain+9.7+9.7mV/?C(min) (Average Slope)+10.3+10.3mV/?C(max) Output Resistance2000400020004000?(max) Line Regulation+4.5V≤V S≤+10V±0.8±0.8mV/V(max) (Note8)±1.2±1.2mV/V(max) Quiescent Current+4.5V≤V S≤+10V130130μA(max) (Note9)180180μA(max) Change of Quiescent+4.5V≤V S≤+10V 2.0 2.0μA(max) Current(Note9)

Temperature Coefficient of+1.0+2.0μA/?C Quiescent Current

Long Term Stability(Note10)T J=125?C,for±0.08±0.08?C

1000hours

Note1:Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.DC and AC electrical specifications do not apply when operating the device beyond its rated operating conditions.

Note2:See AN-450“Surface Mounting Methods and Their Effect on Product Reliability”or the section titled“Surface Mount”found in a current National Semicon-ductor Linear Data Book for other methods of soldering surface mount devices.

Note3:Human body model,100pF discharged through a1.5k?resistor.Machine model,200pF discharged directly into each pin.

Note4:Thermal resistance of the SOT-23package is specified without a heat sink,junction to ambient.

Note5:Limits are guaranteed to National’s AOQL(Average Outgoing Quality Level).

Note6:Accuracy is defined as the error between the output voltage and10mv/?C times the device’s case temperature plus500mV,at specified conditions of volt-age,current,and temperature(expressed in?C).

Note7:Nonlinearity is defined as the deviation of the output-voltage-versus-temperature curve from the best-fit straight line,over the device’s rated temperature range.

Note8:Regulation is measured at constant junction temperature,using pulse testing with a low duty cycle.Changes in output due to heating effects can be com-puted by multiplying the internal dissipation by the thermal resistance.

Note9:Quiescent current is defined in the circuit of Figure1.

Note10:For best long-term stability,any precision circuit will give best results if the unit is aged at a warm temperature,and/or temperature cycled for at least46 hours before long-term life test begins.This is especially true when a small(Surface-Mount)part is wave-soldered;allow time for stress relaxation to occur.The ma-jority of the drift will occur in the first1000hours at elevated temperatures.The drift after1000hours will not continue at the first1000hour rate.

https://www.wendangku.net/doc/1a13726101.html,2

Typical Performance Characteristics To generate these curves the LM50was mounted to a printed circuit board as shown in Figure2.

Thermal Resistance

Junction to Air

DS012030-21Thermal Time Constant

DS012030-22

Thermal Response in Still Air

with Heat Sink(Figure2)

DS012030-23

Thermal Response

in Stirred Oil Bath

with Heat Sink

DS012030-24Start-Up Voltage

vs Temperature

DS012030-25

Thermal Response in Still

Air without a Heat Sink

DS012030-26

Quiescent Current vs Temperature(Figure1)

DS012030-27Accuracy vs Temperature

DS012030-28

Noise Voltage

DS012030-29

https://www.wendangku.net/doc/1a13726101.html, 3

Typical Performance Characteristics

To generate these curves the LM50was mounted to a printed

circuit board as shown in Figure 2.(Continued)1.0Mounting

The LM50can be applied easily in the same way as other integrated-circuit temperature sensors.It can be glued or ce-mented to a surface and its temperature will be within about 0.2?C of the surface temperature.

This presumes that the ambient air temperature is almost the same as the surface temperature;if the air temperature were much higher or lower than the surface temperature,the ac-tual temperature of the LM50die would be at an intermediate temperature between the surface temperature and the air temperature.

To ensure good thermal conductivity the backside of the LM50die is directly attached to the GND pin.The lands and traces to the LM50will,of course,be part of the printed cir-cuit board,which is the object whose temperature is being measured.These printed circuit board lands and traces will not cause the LM50s temperature to deviate from the de-sired temperature.

Alternatively,the LM50can be mounted inside a sealed-end metal tube,and can then be dipped into a bath or screwed into a threaded hole in a tank.As with any IC,the LM50and accompanying wiring and circuits must be kept insulated and dry,to avoid leakage and corrosion.This is especially true if the circuit may operate at cold temperatures where conden-sation can occur.Printed-circuit coatings and varnishes such

as Humiseal and epoxy paints or dips are often used to en-sure that moisture cannot corrode the LM50or its connec-tions.

Temperature Rise of LM50Due to Self-Heating (Thermal Resistance,θJA )

SOT-23SOT-23no heat sink *

small heat fin **

Still air 450?C/W

260?C/W Moving air

180?C/W

*Part soldered to 30gauge wire.

**Heat sink used is 1?2"square printed circuit board with 2oz.foil with part at-

tached as shown in Figure 2.

2.0Capacitive Loads

The LM50handles capacitive loading very well.Without any special precautions,the LM50can drive any capacitive load.The LM50has a nominal 2k ?output impedance (as can be seen in the block diagram).The temperature coefficient of the output resistors is around 1300ppm/?C.Taking into ac-count this temperature coefficient and the initial tolerance of the resistors the output impedance of the LM50will not ex-ceed 4k ?.In an extremely noisy environment it may be nec-essary to add some filtering to minimize noise pickup.It is recommended that 0.1μF be added from V IN to GND to by-

Supply Voltage vs Supply Current

DS012030-30

Start-Up Response

DS012030-31

DS012030-19

FIGURE 2.Printed Circuit Board Used for Heat Sink to Generate All Curves.1?2"Square Printed Circuit Board

with 2oz.Foil or Similar

DS012030-7

FIGURE 3.LM50No Decoupling Required

for Capacitive Load

DS012030-8

FIGURE 4.LM50C with Filter for Noisy Environment https://www.wendangku.net/doc/1a13726101.html,

4

2.0Capacitive Loads

(Continued)

pass the power supply voltage,as shown in Figure 4.In a noisy environment it may be necessary to add a capacitor from the output to ground.A 1μF output capacitor with the 4k ?output impedance will form a 40Hz lowpass filter.Since

the thermal time constant of the LM50is much slower than the 25ms time constant formed by the RC,the overall re-sponse time of the LM50will not be significantly affected.For much larger capacitors this additional time lag will increase the overall response time of the LM50.

3.0Typical Applications

DS012030-17

*R2≈2k with a typical 1300ppm/?C drift.

FIGURE 5.Block Diagram

DS012030-11

FIGURE 6.Centigrade Thermostat/Fan Controller

DS012030-13

FIGURE 7.Temperature To Digital Converter (Serial Output)(+125?C Full Scale)

https://www.wendangku.net/doc/1a13726101.html,

5

3.0Typical Applications(Continued)

DS012030-14

FIGURE8.Temperature To Digital Converter(Parallel TRI-STATE?Outputs for

Standard Data Bus toμP Interface)(125?C Full Scale)

DS012030-16

FIGURE9.LM50With Voltage-To-Frequency Converter And Isolated Output

(?40?C to+125?C;100Hz to1750Hz)

https://www.wendangku.net/doc/1a13726101.html,6

Physical Dimensions inches(millimeters)unless otherwise noted

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

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

labeling,can be reasonably expected to result in a

significant injury to the user.

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.

National Semiconductor

Corporation

Americas

Tel:1-800-272-9959

Fax:1-800-737-7018

Email:support@https://www.wendangku.net/doc/1a13726101.html,

National Semiconductor

Europe

Fax:+49(0)180-5308586

Email:europe.support@https://www.wendangku.net/doc/1a13726101.html,

Deutsch Tel:+49(0)180-5308585

English Tel:+49(0)180-5327832

Fran?ais Tel:+49(0)180-5329358

Italiano Tel:+49(0)180-5341680

National Semiconductor

Asia Pacific Customer

Response Group

Tel:65-2544466

Fax:65-2504466

Email:sea.support@https://www.wendangku.net/doc/1a13726101.html,

National Semiconductor

Japan Ltd.

Tel:81-3-5639-7560

Fax:81-3-5639-7507 https://www.wendangku.net/doc/1a13726101.html,

SOT-23Molded Small Outline Transistor Package(M3)

Order Number LM50BIM3,or LM50CIM3

NS Package Number MA03B

LM50

SOT-23

Single-Supply

Centigrade

Temperature

Sensor 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.

相关文档