LM35 Temperature Sensor (china)

The LM35 Temperature Sensor is one of the most popular and widely used analog temperature sensors in electronics, manufactured originally by Texas Instruments (TI) and available in Chinese-equivalent versions from various manufacturers. What makes this sensor particularly valuable is its simple linear output—it produces an analog voltage that is directly proportional to the Celsius temperature, with a precise scale of 10 millivolts per degree Celsius (10mV/°C). For example, if the output voltage reads 250mV, the temperature is 25°C; if it reads 370mV, the temperature is 37°C. This linear relationship eliminates the need for complex mathematical conversions or lookup tables commonly required with thermistors or thermocouples. The LM35 is housed in a compact TO-92 package, which looks similar to a standard small-signal transistor, with three leads: VCC, GND, and analog output. Unlike many other temperature sensors, the LM35 does not require external calibration or trimming to achieve its rated accuracy of ±0.5°C at room temperature. The sensor operates on a single power supply of 4V to 30V and consumes very little current (around 60µA), making it suitable for battery-powered applications. The LM35C variant is rated for operation from -40°C to +110°C, while the LM35D variant operates from 0°C to +100°C, making them suitable for a wide variety of environmental monitoring applications.

Specifications

• Sensor Type: Analog Linear Temperature Sensor
• Package: TO-92 (3-lead)
• Temperature Range (LM35C): -40°C to +110°C
• Temperature Range (LM35D): 0°C to +100°C
• Output Scale Factor: 10 mV per °C (linear)
• Accuracy at +25°C: ±0.5°C
• Accuracy Over Full Range: ±1°C (typical)
• Supply Voltage Range: +4V to +30V DC
• Current Drain: Less than 60 µA (very low)
• Output Impedance: Low (0.1Ω for 1mA load)
• Non-linearity: ±0.25°C typical
• Self-Heating: Less than 0.08°C in still air
• Calibration Required: No external calibration needed
• Output Type: Analog voltage (directly readable by ADC)
• Response Time: Fast response to temperature changes

Pin Configuration (TO-92 Package)

• Pin 1 (VCC): Positive supply voltage (+4V to +30V).
• Pin 2 (VOUT): Analog output voltage (10 mV/°C).
• Pin 3 (GND): Ground reference.

Applications

• Used in Arduino and Raspberry Pi temperature monitoring projects.
• Essential in weather stations to measure ambient air temperature.
• Employed in HVAC systems for climate control and zone monitoring.
• Used in home automation to track room temperatures.
• Applied in industrial temperature monitoring for equipment safety.
• Common in data loggers and environmental monitoring systems.
• Used in thermostats and temperature regulation circuits.
• Found in incubators and scientific equipment.
• Employed in aquarium and terrarium monitoring.
• Used in refrigeration and cold storage monitoring.
• Applied in automotive temperature sensing for cabin and engine monitoring.
• Common in power supplies and inverters for thermal protection.
• Used in PC and server cooling systems.
• Found in medical devices like digital thermometers.
• Employed in 3D printers for hot-end and bed temperature monitoring.
• Used in greenhouse automation for climate control.
• Applied in battery charging circuits for thermal monitoring.
• Ideal for educational electronics kits and STEM projects.
• Used in smart agriculture systems for soil and air temperature tracking.