PRECISION TEMPERATURE SENSORS
. . . .
DIRECTLY CALIBRATED IN oK 1oC INITIAL ACCURACY OPERATES FROM 450µA TO 5mA LESS THAN 1Ω DYNAMIC IMPEDANCE
Z TO92 (Plastic Package
DESCRIPTION The LM135, LM235, LM335 are precision temperature sensors which can be easily calibrated. They operate as a 2-terminal Zener and the breakdown voltage is directly proportional to theabsolute temperature at 10mV/oK. The circuit has a dynamic impedance of less than 1Ω and operates within a range of current from 450µA to 5mA without alteration of its characteristics. Calibrated at +25oC, the LM135, LM235, LM335 have a typical error of less than 1oC over a 100oC temperature range. Unlike other sensors, the LM135, LM235, LM335 have a linear output. PIN CONNECTIONS
TO92 (Bottom view)V+ 8
D SO8 (Plastic Micropackage)
Part number LM135 LM235 LM335,A Temperature Range –55 C, +150 C –40oC, +125oC –40 C, +100 C
o o o o
Package Z • • • D • • •
SO8 (Top view)
NC 7 NC 6 ADJ 5
1 V 50kΩ 49kΩ 49kΩ 15.6kΩ
3 p F 10kΩ12pF 600Ω 30kΩ
2 AD J
ABSOLUTE MAXIMUM RATINGS
Symbol IR IF Toper Current Reverse Forward Operating Free-air Temperature Range - (note 1) Continuous Intermittent Storage Temperature Range
LM135 15 10 –55 to +150 +150 to +200 –65 to +150
LM235 15 10 –40 to +125 +125 to +150 –65 to +150
LM335,A 15 10
–40 to +100+100 to +125 –65 to +150
Note : 1. Tj ≤ 150 C
Parameter Operating Output Voltage Tcase = +25oC, IR = 1mA Uncalibrated Temperature Error (IR = 1mA) o Tcase = +25 C Tmin. ≤ Tcase ≤ Tmax. Temperature Error with 25oC Calibration Tmin. ≤ Tcase ≤ Tmax., IR = 1mA LM135 - LM235 LM335 LM335A Calibrated Error at Extended TemperatureTcase = Tmax. (intermittent) Non-linearity (IR = 1mA) LM135 - LM235 LM335 LM335A LM135 - LM235 LM335A Min. 2.95 Typ. 2.98 1 2 0.5 0.5 2 0.3 0.3 1 0.3 1.5 1.5 Max. 3.01 3 5 1.5 1 1
LM335 Min. 2.92 Typ. 2.98 2 4 Max.
Unit V 3.04
2 C C
ELECTRICAL CHARACTERISTICS - (note 1)
Parameter Operating output voltage change with current 450µA ≤ IR ≤ 5mA at constanttemperature Dynamic Impedance (IR = 1mA) Output Voltage Temperature Drift Time Constant
o Time Stability (Tcase = +125 C)
LM135 - LM235 Min. Typ. 2.5 0.5 +10 Still Air Air 0.5m/s Stirred Oil 80 10 1 0.2 Max. 10 Min.
LM335,A Typ. 3 0.6 +10 80 10 1 0.2
Unit mV Ω mV/oC s
Note : 1. Accuracy measurements are made in a well-stirred oil bath. For other conditions, selfheating must be considered.
APPLICATION HINTS There is an easy method of calibrating the device for higher accuracies (see typical applications). The single point calibration works because the output of the LM135, LM235, LM335 is proportional to the absolute temperature with the extrapolated output ofsensor going to 0V at 0oK ( –273.15oC). Errors in output voltage versus temperature are only slope. Thus a calibration of the slope at one temperature corrects errors at all temperatures. The output of the circuit (calibrated or not) can be T given by the equation : VOT = VOTO x To where T is the unknown temperature and TO is the reference temperature (in oK). TYPICAL APPLICATIONS BASIC TEMPERATURESENSOR WIDE OPERATING SUPPLY
Vi +5 to +40V LM134, LM234 LM334
Nominally the output is calibrated at 10mV/oK. Precautions should be taken to ensure good sensing accuracy. As in the case of all temperatures sensors, self heating can decrease accuracy. The LM135, LM235, LM335 should operate with a low current, but sufficient to drive the sensor and its calibration circuit to their maximum...