How to Use Buck-Boost Converter: Examples, Pinouts, and Specs

The Buck-Boost Converter (SparkFun COM-15208) is a versatile DC-DC converter capable of stepping up (boosting) or stepping down (bucking) an input voltage to achieve a stable output voltage. This functionality makes it ideal for applications where the input voltage can vary but a consistent output voltage is required. It is widely used in battery-powered devices, renewable energy systems, and embedded electronics.

• Powering microcontrollers and sensors from batteries with fluctuating voltage levels.
• Regulating voltage in portable devices such as smartphones, tablets, and wearables.
• Renewable energy systems, such as solar panels, where input voltage varies with environmental conditions.
• Automotive electronics to stabilize voltage from a car battery.
• Any circuit requiring a stable voltage output from a variable input source.

The following table outlines the key technical details of the SparkFun COM-15208 Buck-Boost Converter:

The SparkFun COM-15208 Buck-Boost Converter has the following pinout:

1. Connect the Input Voltage (VIN):

   • Attach the positive terminal of your power source to the VIN pin.
   • Connect the negative terminal of your power source to the GND pin.

2. Set the Desired Output Voltage:

   • Use the onboard potentiometer to adjust the output voltage.
   • Measure the output voltage at the VOUT pin using a multimeter while adjusting the potentiometer.

3. Connect the Load:

   • Attach the positive terminal of your load to the VOUT pin.
   • Connect the negative terminal of your load to the GND pin.

4. Enable the Converter:

   • Ensure the EN pin is pulled high (connect to VIN or a logic high signal) to enable the converter.
   • If the EN pin is left floating or pulled low, the converter will be disabled.

• Input Voltage Range: Ensure the input voltage remains within the specified range (2.7V to 11.8V) to avoid damaging the converter.
• Output Current Limit: Do not exceed the maximum output current of 2A to prevent overheating or failure.
• Heat Dissipation: For high current loads, consider adding a heatsink or improving airflow around the converter to manage heat.
• Noise Filtering: Add input and output capacitors (e.g., 10µF to 100µF) close to the VIN and VOUT pins to reduce noise and improve stability.
• Feedback Pin (FB): Avoid accidental connections to the FB pin, as it is used internally for voltage regulation.

The Buck-Boost Converter can be used to power an Arduino UNO from a battery. Below is an example circuit and code:

• Connect the battery's positive terminal to the VIN pin of the converter.
• Connect the battery's negative terminal to the GND pin of the converter.
• Adjust the output voltage to 5V using the potentiometer.
• Connect the VOUT pin of the converter to the 5V pin of the Arduino UNO.
• Connect the GND pin of the converter to the GND pin of the Arduino UNO.

// Example code to read a sensor powered by the Buck-Boost Converter
// Ensure the converter is set to output 5V for the Arduino UNO

const int sensorPin = A0; // Analog pin connected to the sensor
int sensorValue = 0;      // Variable to store the sensor reading

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 baud
  pinMode(sensorPin, INPUT); // Set the sensor pin as input
}

void loop() {
  sensorValue = analogRead(sensorPin); // Read the sensor value
  Serial.print("Sensor Value: ");
  Serial.println(sensorValue); // Print the sensor value to the Serial Monitor
  delay(1000); // Wait for 1 second before the next reading
}

1. No Output Voltage:

   • Cause: The EN pin is not connected or is pulled low.
     Solution: Ensure the EN pin is connected to VIN or a logic high signal.
   • Cause: Input voltage is outside the specified range.
     Solution: Verify the input voltage is between 2.7V and 11.8V.

2. Output Voltage is Incorrect:

   • Cause: The potentiometer is not adjusted correctly.
     Solution: Use a multimeter to measure and adjust the output voltage.
   • Cause: Excessive load current.
     Solution: Ensure the load current does not exceed 2A.

3. Overheating:

   • Cause: High current draw or poor ventilation.
     Solution: Reduce the load current or improve heat dissipation with a heatsink.

4. Noise or Instability:

   • Cause: Insufficient input/output capacitors.
     Solution: Add capacitors (10µF to 100µF) close to the VIN and VOUT pins.

Q: Can the Buck-Boost Converter handle reverse polarity on the input?
A: No, the converter does not have reverse polarity protection. Always ensure correct polarity when connecting the input voltage.

Q: Can I use the Buck-Boost Converter to power a Raspberry Pi?
A: Yes, but ensure the output voltage is set to 5V and the load current does not exceed 2A.

Q: How do I know if the converter is working correctly?
A: Measure the output voltage with a multimeter and verify it matches the desired value. Additionally, check for stable operation under load.

Q: Can I use the Buck-Boost Converter with a solar panel?
A: Yes, as long as the solar panel's output voltage is within the input range (2.7V to 11.8V).