**TMP36GT9: A Comprehensive Guide to the Analog Temperature Sensor**
The **TMP36GT9** is a precision, low-voltage, analog temperature sensor from Analog Devices that provides a highly accurate and linear voltage output directly proportional to the Celsius temperature. Its ease of use, reliability, and low cost have made it a staple in countless hobbyist projects and commercial applications, from environmental monitoring systems to thermal protection circuits.
**Operating Principle and Key Features**
At its core, the TMP36GT9 operates by generating an output voltage that scales linearly with the ambient temperature. Its key specifications set it apart:
* **Low Voltage Operation:** It is designed to work on a wide supply voltage range from **2.7 V to 5.5 V**, making it perfectly suited for both 3.3V and 5V microcontroller systems like Arduino, Raspberry Pi, and various development boards.
* **Temperature Range:** It effectively measures temperatures from **-40°C to +125°C**, covering a vast array of potential use cases.
* **High Accuracy:** The sensor boasts an accuracy of **±1°C at +25°C** and typically ±2°C over the entire -40°C to +125°C temperature range, which is more than sufficient for most non-critical measurements.
* **Linear Output:** The output scale factor is **10 mV per °C**. This linear relationship simplifies the code required to convert the analog reading into a temperature value.
* **Low Self-Heating:** The device's extremely low current consumption (below 50 μA) ensures that **minimal self-heating** occurs, preserving the accuracy of the measurement.
**Pin Configuration and Basic Circuit Setup**
The TMP36GT9 comes in a 3-pin TO-92 package:
1. **VS (Pin 1):** The supply voltage input (2.7V - 5.5V).
2. **VOUT (Pin 2):** The analog voltage output pin.
3. **GND (Pin 3):** The ground connection.
The basic circuit is incredibly straightforward. You only need to connect the VS pin to your microcontroller's positive supply (e.g., 3.3V or 5V), connect GND to common ground, and wire the VOUT pin to an **Analog-to-Digital Converter (ADC)** input pin on your microcontroller. A small bypass capacitor (e.g., 0.1μF) placed close to the sensor between VS and GND is often recommended to filter out noise on the power supply line.
**Interpreting the Output and Calculating Temperature**
The output voltage of the TMP36GT9 is calculated using the formula:
**VOUT (in mV) = 500 + (10 * T)**
Where `T` is the temperature in °C. For example:
* At **+25°C**, the output voltage will be 500 mV + (10 mV/°C * 25°C) = **750 mV** or 0.75V.
* At **0°C**, the output voltage is **500 mV**.
* At **-40°C**, the output voltage is 500 mV + (10 mV/°C * -40°C) = **100 mV**.
To get the temperature in code, your microcontroller reads the analog voltage (e.g., a value between 0 and 1023 for a 10-bit ADC on a 5V system). You then convert this reading to a voltage and finally into temperature.
**Sample Arduino Code Snippet**
```cpp
const int sensorPin = A0; // Connect TMP36 Vout to Analog Pin A0
void setup() {
Serial.begin(9600);
}
void loop() {
int reading = analogRead(sensorPin);
float voltage = reading * (5.0 / 1024.0); // Convert ADC reading to voltage (assuming 5V reference)
float temperatureC = (voltage - 0.5) * 100; // Calculate temperature in Celsius
Serial.print("Temperature: ");
Serial.print(temperatureC);
Serial.println(" °C");
delay(1000);
}
```
**Applications and Considerations**
The TMP36GT9 is ideal for:
* **HVAC systems** for basic temperature feedback.
* **Thermal shutdown** protection for other electronics.
* **Weather stations** and home environment monitors.
* **Battery-powered applications** due to its low quiescent current.
When using the sensor, consider protecting it from mechanical stress and excessive moisture. For applications with significant electrical noise, additional filtering on the power and output lines may be necessary to ensure stable readings.
**ICGOODFIND**
The TMP36GT9 stands as a testament to effective and simple analog design. It remains a highly recommended component for beginners and experts alike who need a no-fuss, reliable method for adding temperature sensing to their electronic projects. Its excellent linearity, wide operating voltage, and straightforward interface make it a perennial favorite in the maker community and beyond.
**Keywords:** Analog Temperature Sensor, TMP36GT9, Linear Output, Low Voltage Operation, Arduino-Compatible
