LM35 vs. TMP36: Understanding the Differences in Temperature Sensors
The LM35 and TMP36 are both analog temperature sensors widely used for measuring temperature, but they differ in several key aspects. This article will explore the differences in their output voltage, temperature range, accuracy, power supply, and calibration methods. By understanding these differences, you can choose the right sensor for your specific application needs.
Output Voltage
Both the LM35 and TMP36 output voltages are proportional to the temperature, but the scaling factor differs. The LM35 outputs a voltage that is directly proportional to the Celsius temperature, with a sensitivity of 10 mV per °C. For example, at 25°C, the output voltage will be 250 mV. On the other hand, the TMP36 has a sensitivity of 20 mV per °C, so at the same 25°C, the output voltage would be 750 mV.
Temperature Range
The LM35 operates in a wider temperature range of -55°C to 150°C, making it suitable for a variety of environments. The TMP36, however, has a more limited temperature range, operating between -40°C and 125°C. This narrower range may be more appropriate for applications with less extreme temperature conditions.
Accuracy
The LM35 is known for its high accuracy, typically ±0.5°C at room temperature, which makes it ideal for applications requiring precise temperature measurements. The TMP36, on the other hand, has a typical accuracy of ±2°C, which is less precise than the LM35. This accuracy difference is crucial when deciding which sensor to use, especially in critical applications where temperature readings must be as accurate as possible.
Power Supply
The power supply requirements for the LM35 and TMP36 are also different. The LM35 can operate from a power supply ranging from 4V to 30V, making it suitable for a wide range of power sources. The TMP36, however, operates at a lower voltage range, typically between 2.7V and 5.5V. This makes the TMP36 more suitable for battery-powered devices and applications with limited power supply options.
Calibration
Both the LM35 and TMP36 are calibrated in Celsius, but they have different calibration methods. The LM35 is straightforward to use because it requires no external adjustment and can be directly connected to a microcontroller or sensor interface. The TMP36, however, has an included offset that simplifies interfacing with microcontrollers, as it provides a more consistent voltage output at 0°C. This makes the TMP36 easier to use in low-voltage systems.
Summary
In summary, the LM35 and TMP36 sensors have distinct characteristics. The LM35 is a high-precision sensor with a wide temperature range and higher voltage operation, making it ideal for applications where accuracy and a broader temperature range are crucial. The TMP36, with its lower power supply range and easier interfacing, is more suitable for low-voltage systems and battery-powered devices.
When choosing between these two sensors, consider the specific requirements of your application, such as accuracy, operating range, and power supply constraints. It's important to read the datasheets carefully and pay attention to the accuracy error graphs for each sensor to ensure that you are making the best choice for your project.