How to Use TMP117: Examples, Pinouts, and Specs

The TMP117 is a high-accuracy digital temperature sensor designed to provide precise temperature readings with a resolution of 0.1°C. It features an I2C interface, enabling seamless integration with microcontroller-based systems. The TMP117 operates over a wide temperature range of -55°C to +150°C, making it suitable for a variety of applications, including industrial monitoring, medical devices, HVAC systems, and consumer electronics.

• Industrial temperature monitoring
• Medical devices requiring precise temperature measurements
• HVAC systems for environmental control
• Consumer electronics for thermal management
• IoT devices and data loggers

The TMP117 comes in a 6-pin WSON package. Below is the pinout description:

1. Power Supply: Connect the VDD pin to a regulated power supply (1.8V to 5.5V) and the GND pin to ground.
2. I2C Interface: Connect the SDA and SCL pins to the corresponding I2C data and clock lines of your microcontroller. Use pull-up resistors (typically 4.7 kΩ) on both lines.
3. Address Selection: Use the ADD0 pin to configure the I2C address. Tie it to GND or VDD to select one of two possible addresses.
4. Alert Pin: Optionally, connect the ALERT pin to monitor temperature threshold events.

• Ensure proper decoupling by placing a 0.1 µF capacitor close to the VDD pin.
• Avoid placing the sensor near heat sources to prevent inaccurate readings.
• Use appropriate pull-up resistors for the I2C lines to ensure reliable communication.
• The TMP117 supports standard and fast I2C modes (up to 400 kHz).

Below is an example of how to interface the TMP117 with an Arduino UNO using the Wire library:

#include <Wire.h>

#define TMP117_ADDRESS 0x48 // Default I2C address when ADD0 is tied to GND
#define TEMP_RESULT_REG 0x00 // Register for temperature result

void setup() {
  Wire.begin(); // Initialize I2C communication
  Serial.begin(9600); // Start serial communication for debugging

  // Check if TMP117 is connected
  Wire.beginTransmission(TMP117_ADDRESS);
  if (Wire.endTransmission() != 0) {
    Serial.println("TMP117 not detected. Check connections.");
    while (1); // Halt execution if sensor is not found
  }
  Serial.println("TMP117 detected successfully.");
}

void loop() {
  float temperature = readTemperature();
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
  delay(1000); // Wait 1 second before the next reading
}

float readTemperature() {
  Wire.beginTransmission(TMP117_ADDRESS);
  Wire.write(TEMP_RESULT_REG); // Point to the temperature result register
  Wire.endTransmission();

  Wire.requestFrom(TMP117_ADDRESS, 2); // Request 2 bytes of data
  if (Wire.available() == 2) {
    int16_t rawData = (Wire.read() << 8) | Wire.read(); // Combine MSB and LSB
    return rawData * 0.0078125; // Convert to Celsius (0.0078125°C/LSB)
  } else {
    Serial.println("Error reading temperature.");
    return NAN; // Return NaN if data is unavailable
  }
}

1. TMP117 Not Detected on I2C Bus:

   • Verify the wiring, especially the SDA and SCL connections.
   • Ensure pull-up resistors are present on the I2C lines.
   • Check the ADD0 pin configuration to confirm the correct I2C address.

2. Inaccurate Temperature Readings:

   • Ensure the sensor is not placed near heat sources or in direct sunlight.
   • Verify the power supply voltage is within the specified range (1.8V to 5.5V).
   • Check for proper decoupling with a 0.1 µF capacitor near the VDD pin.

3. I2C Communication Errors:

   • Confirm the I2C clock speed does not exceed 400 kHz.
   • Check for loose or faulty connections in the circuit.

Q: Can the TMP117 operate at 3.3V?
A: Yes, the TMP117 operates within a supply voltage range of 1.8V to 5.5V, so 3.3V is within the acceptable range.

Q: How do I set temperature thresholds for the ALERT pin?
A: The TMP117 allows you to configure high and low temperature thresholds via specific registers. Refer to the TMP117 datasheet for details on programming these registers.

Q: What is the default I2C address of the TMP117?
A: The default I2C address is 0x48 when the ADD0 pin is tied to GND. If ADD0 is tied to VDD, the address changes to 0x49.