How to Use REF-8S: Examples, Pinouts, and Specs

The REF-8S, manufactured by RUET Electra Force, is a precision voltage reference designed to deliver a stable and accurate output voltage. With its low temperature drift and high reliability, the REF-8S is an essential component for applications requiring consistent voltage levels. It is particularly suited for high-accuracy analog systems, such as data acquisition, instrumentation, and precision measurement circuits.

• Analog-to-digital converters (ADCs)
• Digital-to-analog converters (DACs)
• Precision measurement systems
• Industrial control systems
• Test and measurement equipment
• Calibration devices

The REF-8S is engineered to meet the demands of precision applications. Below are its key technical specifications:

The REF-8S is available in an 8-pin SOIC package. The pinout and descriptions are as follows:

1. Power Supply: Connect the VIN pin (Pin 7) to a stable DC power source within the range of 3 V to 15 V. Ensure the power supply is free from noise to maintain the precision of the output voltage.
2. Output Voltage: Connect the VOUT pin (Pin 1) to the load or circuit requiring a stable reference voltage. The output voltage will be 2.5 V, 3.3 V, or 5.0 V, depending on the specific REF-8S model.
3. Ground Connection: Connect the GND pin (Pin 2) to the ground of the circuit.
4. Optional Trimming: If fine-tuning of the output voltage is required, use the TRIM pin (Pin 5) with an appropriate resistor or potentiometer.

• Bypass Capacitors: Place a 0.1 µF ceramic capacitor close to the VIN pin to filter out high-frequency noise. Additionally, a 10 µF electrolytic capacitor can be used for improved stability.
• Thermal Management: Ensure adequate ventilation or heat dissipation if the REF-8S is used in high-temperature environments.
• Avoid Overloading: Do not exceed the ±10 mA output current capability to prevent damage to the component.
• Unused Pins: Leave all NC (No Connection) pins unconnected to avoid interference.

The REF-8S can be used to provide a stable reference voltage for the ADC of an Arduino UNO. Below is an example circuit and code:

• Connect the REF-8S VOUT pin to the AREF pin of the Arduino UNO.
• Connect the REF-8S GND pin to the Arduino GND.
• Connect the REF-8S VIN pin to the Arduino 5V pin.

// Example code to use REF-8S as an external reference for Arduino ADC
void setup() {
  // Configure the ADC to use the external reference voltage
  analogReference(EXTERNAL);

  // Initialize serial communication for debugging
  Serial.begin(9600);
}

void loop() {
  // Read an analog value from pin A0
  int sensorValue = analogRead(A0);

  // Convert the ADC value to voltage (assuming REF-8S provides 2.5V reference)
  float voltage = sensorValue * (2.5 / 1023.0);

  // Print the voltage to the Serial Monitor
  Serial.print("Voltage: ");
  Serial.print(voltage);
  Serial.println(" V");

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

1. No Output Voltage

   • Cause: Incorrect power supply connection or insufficient input voltage.
   • Solution: Verify that the VIN pin is connected to a stable DC voltage within the specified range (3 V to 15 V).

2. Output Voltage is Unstable

   • Cause: Noise on the power supply line or insufficient bypass capacitance.
   • Solution: Add a 0.1 µF ceramic capacitor and a 10 µF electrolytic capacitor close to the VIN pin.

3. Output Voltage is Incorrect

   • Cause: Incorrect model of REF-8S or improper use of the TRIM pin.
   • Solution: Check the model number to ensure the correct output voltage. If using the TRIM pin, verify the resistor or potentiometer value.

4. Component Overheating

   • Cause: Excessive output current or high ambient temperature.
   • Solution: Ensure the load does not exceed the ±10 mA output current limit. Improve ventilation or use a heatsink if necessary.

Q1: Can the REF-8S be used with a 3.3 V power supply?
A1: Yes, the REF-8S operates with input voltages as low as 3 V. Ensure the output voltage model matches your requirements.

Q2: What happens if the TRIM pin is left unconnected?
A2: If the TRIM pin is left unconnected, the REF-8S will output its default precision voltage without any adjustment.

Q3: Can the REF-8S drive multiple loads simultaneously?
A3: Yes, as long as the total current drawn does not exceed the ±10 mA output current capability.

Q4: Is the REF-8S suitable for battery-powered applications?
A4: Yes, its low supply current (1.2 mA typical) makes it suitable for battery-powered systems.