Absolute Maximum Ratings

If MilitaryAerospace specified devices are required

please contact the National Semiconductor Sales

OfficeDistributors for availability and specifications

Supply Current (Externally Set)

10 mA

36V

Feedback Input Voltage Range

Output Short Circuit Duration

Indefinite

Operating Temperature Range

b

Storage Temperature Range

b

Lead Temperature (Soldering 10 seconds)

260 C

Parameter

Conditions

Min

Typ

Max

Units

SENSOR

Output Voltage

236

248

260

V

Output Voltage

288

298

308

V

Output Voltage

346

358

370

V

Linearity

D

05

2

%

Long-Term Stability

03

%

Repeatability

03

%

VOLTAGE REFERENCE

Reverse Breakdown Voltage

655

685

725

V

Reverse Breakdown Voltage

10

35

mV

Change With Current

Temperature Stability

20

85

mV

Dynamic Impedance

30

X

RMS Noise Voltage

30

m

V

Long Term Stability

60

mV

OP AMP

Input Bias Current

35

150

nA

Input Bias Current

45

250

nA

Voltage Gain

2500

15000

VV

Output Leakage Current

02

2

m

A

Output Leakage Current

(Note 3)

10

8

m

A

Output Source Current

10

m

A

Output Sink Current

20

mA

Note 1

Note 2

the feedback sense voltage and includes errors in both the sensor and op amp This voltage is specified for the sensor in a rapidly stirred oil bath The output is

Note 3

Application Hints

Although the LM3911 is designed to be totally trouble-free

certain precautions should be taken to insure the best pos-

sible performance

As with any temperature sensor internal power dissipation

will raise the sensor’s temperature above ambient Nominal

suggested operating current for the shunt regulator is 10

mA and causes 70 mW of power dissipation In free still air

this raises the package temperature by about 12 K Al-

though the regulator will operate at higher reverse currents

and the output will drive loads up to 50 mA these higher

currents will raise the sensor temperature to about 19 K

above ambient-degrading accuracy Therefore the sensor

should be operated at the lowest possible power level

With moving air liquid or surface temperature sensing self-

heating is not as great a problem since the measured

media will conduct the heat from the sensor Also there are

many small heat sinks designed for transistors which will

improve heat transfer to the sensor from the surrounding

medium A small finned clip-on heat sink is quite effective in

free-air It should be mentioned that the LM3911 die is on

the base of the package and therefore coupling to the base

is preferable

The internal reference regulator provides a temperature sta-

ble voltage for offsetting the output or setting a comparison

point in temperature controllers However since this refer-

ence is at the same temperature as the sensor temperature

changes will also cause reference drift For application

where maximum accuracy is needed an external reference

should be used Of course for fixed temperature controllers

the internal reference is adequate

2