LMx35, LMx35A Precision Temperature Sensors
- SNIS160E May 1999 – February 2015 LM135 , LM135A , LM235 , LM235A , LM335 , LM335A
  
  PRODUCTION DATA.

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DATA SHEET

LMx35, LMx35A Precision Temperature Sensors

1 Features

Directly Calibrated to the Kelvin Temperature Scale
1°C Initial Accuracy Available
Operates from 400 μA to 5 mA
Less than 1-Ω Dynamic Impedance
Easily Calibrated
Wide Operating Temperature Range
200°C Overrange
Low Cost

2 Applications

Power Supplies
Battery Management
HVAC
Appliances

3 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/°K. With less than 1-Ω dynamic impedance, the device operates over a current range of 400 μA to 5 mA with virtually no change in performance. When calibrated at 25°C, the LM135 has typically less than 1°C error over a 100°C temperature range. Unlike other sensors, the LM135 has a linear output.

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

The LM135 operates over a −55°C to 150°C temperature range while the LM235 operates over a −40°C to 125°C temperature range. The LM335 operates from −40°C to 100°C. The LMx35 devices are available packaged in hermetic TO transistor packages while the LM335 is also available in plastic TO-92 packages.

Device Information⁽¹⁾

PART NUMBER	PACKAGE	BODY SIZE (NOM)
LM135	TO-46 (3)	4.699 mm × 4.699 mm
LM135A	TO-46 (3)	4.699 mm × 4.699 mm
LM235	TO-92 (3)	4.30 mm × 4.30 mm
LM235A	TO-92 (3)	4.30 mm × 4.30 mm
LM335	SOIC (8)	4.90 mm × 3.91 mm
LM335A	SOIC (8)	4.90 mm × 3.91 mm

For all available packages, see the orderable addendum at the end of the datasheet.

Basic Temperature Sensor Simplified Schematic

Calibrated Sensor

4 Revision History

Changes from D Revision (March 2013) to E Revision

Added Pin Configuration and Functions section, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information sectionGo

Changes from C Revision (November 2012) to D Revision

Changed layout of National Data Sheet to TI formatGo

5 Pin Configuration and Functions

TO-46 (NDV)

3 Pins

Bottom View

TO-92 (LP)

3 Pins

Bottom View

SOIC (D)

8 Pins

Top View

Pin Functions

PIN				I/O	DESCRIPTION
NAME	TO-46	TO-92	SO8	I/O	DESCRIPTION
N.C.	—	—	1	—	No Connection
	—	—	2
	—	—	3
–	—	—	4	O	Negative output
ADJ	—	—	5	I	Calibration adjust pin
N.C.	—	—	6	—	No Connection
N.C.	—	—	7	—	No Connection
+	—	—	8	I	Positive input

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)⁽¹⁾⁽³⁾⁽²⁾⁽⁴⁾

		MIN	MAX	UNIT
Reverse Current			15	mA
Forward Current			10	mA
Storage temperature, T_stg	8-Pin SOIC Package	−65	150	°C
Storage temperature, T_stg	TO / TO-92 Package	−60	150	°C

(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications.

(3) Refer to RETS135H for military specifications.

(4) Soldering process must comply with the Reflow Temperature Profile specifications. Refer to http://www.ti.com/packaging.

6.2 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)

			MIN	NOM	MAX	UNIT
Specified Temperature	LM135, LM135A	Continuous (T_MIN ≤ T_A ≤ T_MAX)	−55		150	°C
	LM135, LM135A	Intermittent ⁽¹⁾	150		200	°C
	LM235, LM235A	Continuous (T_MIN ≤ T_A ≤ T_MAX)	−40		125	°C
	LM235, LM235A	Intermittent ⁽¹⁾	125		150	°C
	LM335, LM335A	Continuous (T_MIN ≤ T_A ≤ T_MAX)	−40		100	°C
	LM335, LM335A	Intermittent ⁽¹⁾	100		125	°C
Forward Current			0.4	1	5	mA

(1) Continuous operation at these temperatures for 5,000 hours for LP package may decrease life expectancy of the device.

6.3 Thermal Information

THERMAL METRIC⁽¹⁾		LM335 / LM335A	LM235 / LM235A	LM135 / LM135A	UNIT
		SOIC (D)	TO-92 (LP)	TO-46 (NDV)
		8 PINS	3 PINS	3 PINS
R_θJA	Junction-to-ambient thermal resistance	165	202	400	°C/W
R_θJC	Junction-to-case thermal resistance	—	170	—	°C/W

(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

6.4 Temperature Accuracy: LM135/LM235, LM135A/LM235A⁽¹⁾

PARAMETER		TEST CONDITIONS	LM135A/LM235A			LM135/LM235			UNIT
PARAMETER		TEST CONDITIONS	MIN	TYP	MAX	MIN	TYP	MAX	UNIT
Operating Output Voltage		T_C = 25°C, I_R = 1 mA	2.97	2.98	2.99	2.95	2.98	3.01	V
Uncalibrated Temperature Error		T_C = 25°C, I_R = 1 mA		0.5	1		1	3	°C
Uncalibrated Temperature Error		T_MIN ≤ T_C ≤ T_MAX, I_R = 1 mA		1.3	2.7		2	5	°C
Temperature Error with 25°C		T_MIN ≤ T_C ≤ T_MAX, I_R = 1 mA		0.3	1		0.5	1.5	°C
Calibration	Calibrated Error at Extended	T_C = T_MAX (Intermittent)		2			2		°C
Temperature	Non-Linearity	I_R = 1 mA		0.3	0.5		0.3	1	°C

6.5 Temperature Accuracy: LM335, LM335A⁽¹⁾

PARAMETER		TEST CONDITIONS	LM335A			LM335			UNIT
PARAMETER		TEST CONDITIONS	MIN	TYP	MAX	MIN	TYP	MAX	UNIT
Operating Output Voltage		T_C = 25°C, I_R = 1 mA	2.95	2.98	3.01	2.92	2.98	3.04	V
Uncalibrated Temperature Error		T_C = 25°C, I_R = 1 mA		1	3		2	6	°C
Uncalibrated Temperature Error		T_MIN ≤ T_C ≤ T_MAX, I_R = 1 mA		2	5		4	9	°C
Temperature Error with 25°C		T_MIN ≤ T_C ≤ T_MAX, I_R = 1 mA		0.5	1		1	2	°C
Calibration	Calibrated Error at Extended	T_C = T_MAX (Intermittent)		2			2		°C
Temperature	Non-Linearity	I_R = 1 mA		0.3	1.5		0.3	1.5	°C

6.6 Electrical Characteristics

See ⁽¹⁾.

PARAMETER	TEST CONDITIONS	LM135/LM235/LM135A/LM235A			LM335/LM335A			UNIT
PARAMETER	TEST CONDITIONS	MIN	TYP	MAX	MIN	TYP	MAX	UNIT
Operating Output Voltage Change with Current	400 μA ≤ I_R ≤ 5 mA, At Constant Temperature		2.5	10		3	14	mV
Dynamic Impedance	I_R = 1 mA		0.5			0.6		Ω
Output Voltage Temperature Coefficient			10			10		mV/°C
Time Constant	Still Air		80			80		sec
	100 ft/Min Air		10			10		sec
	Stirred Oil		1			1		sec
Time Stability	T_C = 125°C		0.2			0.2		°C/khr

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

6.7 Typical Characteristics

Figure 1. Reverse Voltage Change

Figure 3. Reverse Characteristics

Figure 5. Dynamic Impedance

Figure 7. Thermal Resistance Junction To Air

Figure 9. Thermal Response In Still Air

Figure 11. Forward Characteristics

Figure 2. Calibrated Error

Figure 4. Response Time

Figure 6. Noise Voltage

Figure 8. Thermal Time Constant

Figure 10. Thermal Response In Stirred Oil Bath

7 Detailed Description

7.1 Overview

The LM135 operates over a −55°C to 150°C temperature range while the LM235 operates over a −40°C to 125°C temperature range. The LM335 operates from −40°C to 100°C.

Operating as a 2-terminal zener, the LM135 has a breakdown voltage directly proportional to absolute temperature at 10 mV/°K. With less than 1-Ω dynamic impedance, the device operates over a current range of 400 μA to 5 mA with virtually no change in performance. When calibrated at 25°C, the LM135 has typically less than 1°C error over a 100°C temperature range. Unlike other sensors, the LM135 has a linear output.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Temperature Calibration Using ADJ Pin

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 (as shown in Figure 12) 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 0-V output at 0 K (−273.15°C). 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:

Equation 1.

where

T is the unknown temperature in degrees Kelvin
T_o is a reference temperature 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/K.

Calibrate for 2.982V at 25°C

Figure 12. Calibrated Sensor

7.4 Device Functional Modes

The LM135 has two functional modes calibrated and uncalibrated. For optimum accuracy, a one point calibration is recommended. For more information on calibration, see Temperature Calibration Using ADJ Pin.