NSC LM335MWC, LM335M, LM335H, LM335AM, LM335Z Datasheet

May 1999

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 +10 mV/ÊK. With less than 1Ω dynamic impedance the device operates over a current range of 400 µA to 5 mA with virtually no change in performance. When calibrated at 25ÊC the LM135 has typically less than 1ÊC error over a 100ÊC temperature range. Unlike other sensors the LM135 has a linear output.

Applications for the LM135 include almost any type of temperature sensing over a −55ÊC to +150ÊC temperature range. The low impedance and linear output make interfacing to readout or control circuitry especially easy.

The LM135 operates over a −55ÊC to +150ÊC temperature range while the LM235 operates over a −40ÊC to +125ÊC

temperature range. The LM335 operates from −40ÊC to +100ÊC. The LM135/LM235/LM335 are available packaged in hermetic TO-46 transistor packages while the LM335 is also available in plastic TO-92 packages.

Features

nDirectly calibrated in ÊKelvin

n1ÊC initial accuracy available

nOperates from 400 µA to 5 mA

nLess than 1Ω dynamic impedance

nEasily calibrated

nWide operating temperature range

n200ÊC overrange

nLow cost

Schematic Diagram

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

© 1999 National Semiconductor Corporation

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Connection Diagrams

TO-92	SO-8
Plastic Package		TO-46
	Surface Mount Package
		Metal Can Package*

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	Bottom View		DS005698-26
	Order Number LM335Z
		DS005698-25	*Case is connected to negative pin
	or LM335AZ
		Order Number LM335M	Bottom View
	See NS Package
		See NS Package	Order Number LM135H,
	Number Z03A
		Number M08A	LM135H-MIL, LM235H,
			LM335H, LM135AH,
			LM235AH or LM335AH
			See NS Package
			Number H03H

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Absolute Maximum Ratings (Note 4)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Reverse Current	15 mA
Forward Current	10 mA
Storage Temperature
TO-46 Package	−60ÊC to +180ÊC
TO-92 Package	−60ÊC to +150ÊC
SO-8 Package	−65ÊC to +150ÊC

Specified Operating Temp. Range
	Continuous	Intermittent
		(Note 2)
LM135, LM135A	−55ÊC to +150ÊC	150ÊC to 200ÊC
LM235, LM235A	−40ÊC to +125ÊC	125ÊC to 150ÊC
LM335, LM335A	−40ÊC to +100ÊC	100ÊC to 125ÊC

Lead Temp. (Soldering, 10 seconds)
TO-92 Package:	260ÊC
TO-46 Package:	300ÊC
SO-8 Package:	300ÊC
Vapor Phase (60 seconds):	215ÊC
Infrared (15 seconds):	220ÊC

Temperature Accuracy (Note 1)

LM135/LM235, LM135A/LM235A

Parameter	Conditions	LM135A/LM235A			LM135/LM235			Units
		Min	Typ	Max	Min	Typ	Max
Operating Output Voltage	TC = 25ÊC, IR = 1 mA	2.97	2.98	2.99	2.95	2.98	3.01	V
Uncalibrated Temperature Error	TC = 25ÊC, IR = 1 mA		0.5	1		1	3	ÊC
Uncalibrated Temperature Error	TMIN ≤ TC ≤ TMAX, IR = 1 mA		1.3	2.7		2	5	ÊC
Temperature Error with 25ÊC	TMIN ≤ TC ≤ TMAX, IR = 1 mA		0.3	1		0.5	1.5	ÊC
Calibration
Calibrated Error at Extended	TC = TMAX (Intermittent)		2			2		ÊC
Temperatures
Non-Linearity	IR = 1 mA		0.3	0.5		0.3	1	ÊC

Temperature Accuracy (Note 1)

LM335, LM335A

Parameter	Conditions		LM335A			LM335		Units
		Min	Typ	Max	Min	Typ	Max
Operating Output Voltage	TC = 25ÊC, IR = 1 mA	2.95	2.98	3.01	2.92	2.98	3.04	V
Uncalibrated Temperature Error	TC = 25ÊC, IR = 1 mA		1	3		2	6	ÊC
Uncalibrated Temperature Error	TMIN ≤ TC ≤ TMAX, IR = 1 mA		2	5		4	9	ÊC
Temperature Error with 25ÊC	TMIN ≤ TC ≤ TMAX, IR = 1 mA		0.5	1		1	2	ÊC
Calibration
Calibrated Error at Extended	TC = TMAX (Intermittent)		2			2		ÊC
Temperatures
Non-Linearity	IR = 1 mA		0.3	1.5		0.3	1.5	ÊC

Electrical Characteristics (Note 1)

		LM135/LM235				LM335
Parameter	Conditions	LM135A/LM235A				LM335A		Units
		Min	Typ	Max	Min	Typ	Max
Operating Output Voltage	400 µA≤IR≤5 mA		2.5	10		3	14	mV
Change with Current	At Constant Temperature
Dynamic Impedance	IR=1 mA		0.5			0.6		Ω
Output Voltage Temperature			+10			+10		mV/ÊC
Coefficient
Time Constant	Still Air		80			80		sec
	100 ft/Min Air		10			10		sec
	Stirred Oil		1			1		sec
Time Stability	TC=125ÊC		0.2			0.2		ÊC/khr

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Electrical Characteristics (Note 1) (Continued)

Note 1: Accuracy measurements are made in a well-stirred oil bath. For other conditions, self heating must be considered.

Note 2: Continuous operation at these temperatures for 10,000 hours for H package and 5,000 hours for Z package may decrease life expectancy of the device.

Note 3:

Thermal Resistance	TO-92	TO-46	SO-8
θJA (junction to ambient)	202ÊC/W	400ÊC/W	165ÊC/W
θJC (junction to case)	170ÊC/W	N/A	N/A

Note 4: Refer to RETS135H for military specifications.

Typical Performance Characteristics

Reverse Voltage Change Calibrated Error Reverse Characteristics

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Response Time	Dynamic Impedance		Noise Voltage

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Thermal Resistance	Thermal Time Constant	Thermal Response in Still Air
Junction to Air

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Typical Performance Characteristics (Continued)

Thermal Response in Stirred Oil Bath

Forward Characteristics

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Application Hints

CALIBRATING THE LM135

Included on the LM135 chip is an easy method of calibrating the device for higher accuracies. A pot connected across the LM135 with the arm tied to the adjustment terminal allows a 1-point calibration of the sensor that corrects for inaccuracy over the full temperature range.

This single point calibration works because the output of the LM135 is proportional to absolute temperature with the extrapolated output of sensor going to 0V output at 0ÊK (−273.15ÊC). Errors in output voltage versus temperature are only slope (or scale factor) errors so a slope calibration at one temperature corrects at all temperatures.

The output of the device (calibrated or uncalibrated) can be expressed as:

where T is the unknown temperature and To is a reference temperature, both expressed in degrees Kelvin. By calibrating the output to read correctly at one temperature the output at all temperatures is correct. Nominally the output is calibrated at 10 mV/ÊK.

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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.

If the sensor is used in an ambient where the thermal resistance is constant, self heating errors can be calibrated out. This is possible if the device is run with a temperature stable current. Heating will then be proportional to zener voltage and therefore temperature. This makes the self heating error proportional to absolute temperature the same as scale factor errors.

WATERPROOFING SENSORS

Meltable inner core heat shrinkable tubing such as manufactured by Raychem can be used to make low-cost waterproof sensors. The LM335 is inserted into the tubing about 1¤2" from the end and the tubing heated above the melting point of the core. The unfilled 1¤2" end melts and provides a seal over the device.

Typical Applications

Basic Temperature Sensor

Calibrated Sensor

Wide Operating Supply

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*Calibrate for 2.982V at 25ÊC

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