LM35 Waterproof Temperature Sensor Probe - Analog

The LM335 Precision Temperature Sensor is a versatile, low-cost solution engineered for accurate thermal measurement in a wide range of electronics applications. Designed for easy integration, it operates as a 2-terminal Zener diode with a breakdown voltage linearly proportional to absolute temperature (Kelvin), making it ideal for digital temperature loggers, environmental monitors, and control systems. With a high degree of accuracy and a wide operational current range from 450µA to 5mA, the LM335 ensures stable performance without the need for calibration or external circuitry.

Unlike thermocouples that demand complex interfacing, or thermistors that require intricate calibration procedures, the LM335 offers a plug-and-play experience with a direct Kelvin output. Its linearity, low dynamic impedance (less than 1 Ohm), and broad sensing range of -40°C to +100°C make it suitable for industrial, automotive, and laboratory-grade applications where precision and dependability are essential.

Key Features

• Direct Kelvin Calibration: Outputs 10mV per Kelvin, simplifying the conversion to Celsius or Fahrenheit.

• High Initial Accuracy: ±1°C accuracy at 25°C without external calibration.

• Wide Operating Current Range: Functions reliably from 450µA to 5mA, providing design flexibility.

• Low Dynamic Impedance: Less than 1 Ohm ensures minimal voltage variation under changing load conditions.

• Extended Temperature Sensing Range: Measures from -40°C to +100°C, suitable for both low and moderate thermal applications.

• No Calibration Required: Provides accurate and linear response out of the box.

• Interface-Free Design: Unlike thermocouples, no signal conditioning or amplifiers needed.

• Easy to Implement: 2-terminal configuration simplifies circuit design and PCB layout.

 

 

Before we can get a Kevlin reading of the temperature, the analog output voltage must first be read. This will be the raw value divided by 1024 times 5000. It is divided by 1024 because a span of 1024 occupies 5V. We get the ratio of the raw value to the full span of 1024 and then multiply it by 5000 to get the millivolt value. Since the output pin can give out a maximum of 5 volts (1024), 1024 represents the full possible range it can give out. The raw voltage over this 1024 (value) therefore represents the ratio of how much power the output pin is outputting against this full range. Once we have this ratio, we then multiply it by 5000 to give the millivolt value. This is because there is 5000 millvolts in 5 volts.

Once this analog voltage in millivolts is calculated, we then can find the temperature in kelvin by the equation: (millivolts/10).

To get the equivalent temperature in Celsius, we subtract the Kelvin value by 273. Once we obtain this Celsius value, we can convert into Fahrenheit with the following equation: (celsius * 1.8 +32). At the end of this program, we put a delay of 1000ms to take the temperature reading every second.