LM35 Analog Temperature Sensor TO-92

LM35 Analog Temperature Sensor TO-92 is a precision integrated circuit that measures temperature with linear output scaling, making it one of the most popular thermal sensors for electronics prototyping and commercial devices. This sensor provides an output voltage directly proportional to the Celsius (Centigrade) temperature. Consequently, it eliminates the need for complex, and often inaccurate, external calibration circuits or non-linear adjustments required by thermistors. Furthermore, the LM35 boasts high accuracy and a low self-heating effect, ensuring that the measurement reflects the true ambient temperature. You can easily connect and power the device using standard microcontroller boards like Arduino or Raspberry Pi, delivering reliable, real-time temperature data for monitoring and control systems.

Key Features:

• Direct Celsius Output: The sensor provides a linear output scale of 10 mV/°C, simplifying temperature calculation without requiring offset adjustments.
• High Accuracy: Guarantees a typical accuracy of ±0.5°C at 25°C, ensuring reliable temperature readings for critical systems.
• Low Self-Heating: The low operating current (< 60 µA) causes negligible self-heating, typically less than 0.1°C, which preserves measurement integrity.
• Wide Temperature Range: Operates reliably across a broad range from −55°C to +150°C, although the TO-92 package is generally limited to 0°C to +100°C.
• Low Output Impedance: The low output impedance allows the sensor to drive loads efficiently over long wires without significant voltage drop.

Technical Specifications:

• Scale Factor: 10.0 mV/°C (0.01 V/°C)
• Supply Voltage Range (V_S): 4 V to 30 V
• Operating Current (I_Q): Less than 60 µA (quiescent current)
• Output Voltage Range: 0 V to 1.5 V (for 0°C to 150°C operation with single supply)
• Linearity: Very High (Typically ±¼°C over the full range)
• Temperature Range (TO-92): 0°C to +100°C

Mechanical Specifications:

• Package Type: TO-92 (Standard Transistor Package)
• Mounting: Through-Hole Technology (THT)
• Pin Configuration: 3-Pin, single row for easy PCB insertion.
• Thermal Resistance: R_θJA ≈ 200°C/W (Junction to Ambient)

Dimensions:

• Body Diameter: ≈ 4.8 mm
• Body Height: ≈ 4.3 mm
• Lead Spacing (E): 1.27 mm (Standard THT pitch)
• Overall Dimensions: Compact and highly versatile for tight installations.

Pinout and Wiring:

• Pin 1 (V_S): Connect the input voltage supply, typically 5V from a microcontroller or battery.
• Pin 2 (V_OUT): This is the Analog Output. Connect it to an Analog-to-Digital Converter (ADC) pin on your microcontroller.
• Pin 3 (GND): Connect to the system ground (0 V).
• Wiring Note: Therefore, you must ensure you orient the flat side of the sensor correctly when identifying the pins, as reversing the power can damage the IC.

Datasheet Reference:

• Download LM35 Precision Centigrade Temperature Sensor Datasheet

Commonly Used in:

• Educational Projects: A standard component in Arduino and Raspberry Pi based temperature reading tutorials.
• Data Loggers: Integrated into devices that record environmental temperature over time.
• Industrial Monitoring: Utilized in non-critical industrial applications for machinery and enclosure temperature surveillance.

Applications:

• HVAC Systems: Monitoring ambient air temperature for automated heating and cooling controls.
• Temperature Alarms: Triggering alerts when temperatures exceed pre-set thresholds in equipment enclosures or rooms.
• Digital Thermometers: Forming the sensing core of various consumer and industrial thermometers.
• Climate Control Systems: Providing precise input for humidity and thermal management in greenhouses or server racks.

Equivalent Models:

• LM35DZ: The most common derivative of the LM35, specified for the 0°C to +100°C commercial temperature range.
• TMP36: A similar low-cost, low-power sensor, however, it features an output scaled for Kelvin but offset to provide 0V at −50°C.
• LM34: This variant provides an equivalent output scaled for Fahrenheit, consequently requiring different conversion formulas.

Package Includes:

• 1 x LM35 Analog Temperature Sensor IC (TO-92 Package)