LM235A

Part: LM135, LM135A, LM235, LM235A, LM335, LM335A from Texas Instruments

Type: Precision Temperature Sensor

Description: Precision, easily-calibrated integrated circuit temperature sensors operating as a 2-terminal zener with a breakdown voltage directly proportional to absolute temperature at 10 mV/°K, operating over a current range of 400 μA to 5 mA with less than 1-Ω dynamic impedance.

Operating Conditions:

• Supply current: 400 μA to 5 mA
• Operating temperature:
  • LM135, LM135A: -55 to 150 °C
  • LM235, LM235A: -40 to 125 °C
  • LM335, LM335A: -40 to 100 °C
• Output proportionality: 10 mV/°K

Absolute Maximum Ratings:

• Max supply voltage: Not applicable (2-terminal zener)

Key Specs:

• Output Voltage Proportionality: 10 mV/°K
• Operating Output Voltage (LM135A/LM235A, T_C = 25°C, I_R = 1 mA): 2.97 V to 2.99 V (Typ 2.98 V)
• Uncalibrated Temperature Error (LM135A/LM235A, T_MIN ≤ T_C ≤ T_MAX, I_R = 1 mA): Typ 2 °C, Max 5 °C
• Temperature Error with 25°C Calibration (LM135A/LM235A, T_MIN ≤ T_C ≤ T_MAX, I_R = 1 mA): Typ 0.5 °C, Max 1 °C
• Operating Current Range: 400 μA to 5 mA
• Dynamic Impedance (I_R = 1 mA): Less than 1 Ω
• Non-Linearity (LM135A/LM235A, I_R = 1 mA): Typ 0.3 °C, Max 1.5 °C
• Operating Output Voltage Change with Current (LM135/LM235/LM135A/LM235A, 400 μA ≤ I_R ≤ 5 mA): Typ 2.5 mV, Max 10 mV

Features:

• Directly Calibrated to the Kelvin Temperature
• 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

Applications:

• Power Supplies
• Battery Management
• HVAC
• Appliances

Package:

• TO-46 (3)
• TO-92 (3)
• SOIC (8)

• Directly Calibrated to the Kelvin Temperature
• 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

• Power Supplies
• Battery Management
• HVAC
• Appliances

Pin Functions

6 Specifications

6.1 Absolute Maximum Ratings

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

⁽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.

Refer to RETS135H for military specifications.

6.2 Recommended Operating Conditions

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

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

6.3 Thermal Information

⁽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⁾

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

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³⁾ If Military/Aerospace specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications.

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

See (1).

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

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

⁽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.

Refer to RETS135H for military specifications.

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

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

6.3 Thermal Information

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

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

To insure good sensing accuracy, several precautions must be taken. Like any temperature-sensing device, selfheating 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.