How to Use Sensor NTC LM393: Examples, Pinouts, and Specs

The Sensor NTC LM393 is a temperature sensing device that utilizes a Negative Temperature Coefficient (NTC) thermistor to measure temperature changes. The LM393 component of the sensor is a dual differential comparator integrated circuit, which is used to compare the voltage level from the NTC thermistor with a reference voltage. This sensor is widely used in applications such as temperature monitoring systems, environmental controls, and electronic thermometers due to its sensitivity and quick response to temperature changes.

• Operating Voltage (Vcc): 3.3V to 5V
• Temperature Measurement Range: Typically -55°C to 150°C (dependent on the NTC thermistor used)
• Output Type: Digital (comparator output)
• Comparator IC: LM393
• Accuracy: Dependent on the NTC thermistor and external circuitry

1. Power Supply: Connect the Vcc pin to a 3.3V or 5V power supply and the GND pin to the ground of your circuit.
2. Output Connections: The DO pin provides a digital output which can be connected to a digital input pin on a microcontroller like an Arduino. The AO pin provides an analog output that represents the temperature reading and can be connected to an analog input pin.
3. Setting Reference Voltage: The reference voltage at pin 6 can be set using a potentiometer or a fixed voltage divider to create a temperature threshold for the digital output.

• Ensure that the power supply voltage does not exceed the maximum rating of the sensor.
• Use appropriate pull-up or pull-down resistors on the output lines as required by your microcontroller.
• Calibrate the sensor for accurate temperature readings by adjusting the reference voltage and using a known temperature source for comparison.
• Avoid placing the sensor near heat-generating components to prevent false readings.

// Define the digital and analog pin connections
const int digitalOutputPin = 2; // DO pin connected to digital pin 2
const int analogOutputPin = A0; // AO pin connected to analog pin A0

void setup() {
  pinMode(digitalOutputPin, INPUT); // Set the digital pin as input
  Serial.begin(9600); // Start serial communication at 9600 baud rate
}

void loop() {
  int analogValue = analogRead(analogOutputPin); // Read the analog value
  bool isHot = digitalRead(digitalOutputPin); // Read the digital value

  // Convert the analog value to a temperature (example conversion)
  float temperature = (analogValue * 5.0 / 1023.0) * 100.0; // Assuming linear scaling

  // Print the temperature and hot status
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.print(" C, Hot: ");
  Serial.println(isHot ? "Yes" : "No");

  delay(1000); // Wait for 1 second before reading again
}

• Inaccurate Temperature Readings: Ensure that the sensor is properly calibrated and that there is no self-heating affecting the readings.
• No Output from DO Pin: Check the reference voltage setting and ensure that the temperature has crossed the threshold set by the reference voltage.
• Fluctuating Readings: Ensure that there are no drafts or sudden temperature changes affecting the sensor. Also, check for stable power supply and good connections.

• Calibrate the sensor using a known temperature source and adjust the reference voltage accordingly.
• Use a stable and noise-free power supply to prevent fluctuations in readings.
• Ensure that the sensor is placed in a location with minimal temperature interference for accurate readings.

Q: Can the sensor be used with both 3.3V and 5V systems? A: Yes, the sensor can operate within a range of 3.3V to 5V.

Q: How can I improve the accuracy of the sensor? A: Calibration is key. Use a precise temperature source and adjust the reference voltage to match the known temperature.

Q: What is the purpose of the LM393 in this sensor? A: The LM393 is a comparator IC that compares the voltage from the NTC thermistor with a reference voltage to provide a digital output when a certain temperature threshold is reached.