How to Use 5V UPS: Examples, Pinouts, and Specs

A 5V Uninterruptible Power Supply (UPS) is a compact power management device designed to provide a stable 5V output to electronic devices during power outages or fluctuations. It ensures uninterrupted operation by seamlessly switching to a rechargeable battery when the primary power source is unavailable. This makes it an essential component for critical systems, IoT devices, Raspberry Pi boards, and other low-power electronics that require reliable power delivery.

• Backup power for Raspberry Pi, Arduino, and other microcontroller-based systems.
• IoT devices deployed in remote or unstable power environments.
• Network equipment such as routers and modems.
• Portable electronics requiring stable 5V power.
• Data logging systems to prevent data loss during power interruptions.

The following table outlines the key technical details of the 5V UPS:

The 5V UPS typically includes the following pins or connectors:

1. Connect the Input Power Source:
   Attach a 5V DC power source to the VIN and GND pins. Ensure the input voltage is within the specified range to avoid damage.

2. Connect the Load:
   Connect the device or circuit requiring backup power to the VOUT and GND pins. Verify that the load does not exceed the maximum output current (2A).

3. Attach the Battery:
   If the UPS requires an external battery, connect the positive and negative terminals of the battery to the BAT+ and BAT- pins, respectively. Use a compatible lithium-ion or lithium-polymer battery.

4. Monitor Indicators (Optional):

   • Use the CHG_IND pin to monitor the charging status of the battery.
   • Use the PWR_GOOD pin to check if the output voltage is stable.

5. Test the UPS Functionality:
   Disconnect the input power source to simulate a power outage. Verify that the UPS seamlessly switches to battery power and maintains a stable 5V output.

• Battery Selection: Use a battery with sufficient capacity to meet the runtime requirements of your application. Ensure the battery voltage matches the UPS specifications.
• Heat Management: Avoid placing the UPS in enclosed spaces without ventilation, as heat may build up during operation or charging.
• Load Limitations: Do not exceed the maximum output current (2A) to prevent damage to the UPS or connected devices.
• Regular Maintenance: Periodically check the battery health and replace it if the capacity significantly degrades.

The following example demonstrates how to connect a 5V UPS to an Arduino UNO for uninterrupted operation:

• Connect the VOUT pin of the UPS to the 5V pin of the Arduino UNO.
• Connect the GND pin of the UPS to the GND pin of the Arduino UNO.
• Optionally, monitor the PWR_GOOD pin to detect power stability.

// Example code to monitor the PWR_GOOD pin of a 5V UPS
const int powerGoodPin = 2; // Connect PWR_GOOD pin to Arduino digital pin 2
const int ledPin = 13;      // Built-in LED on Arduino UNO

void setup() {
  pinMode(powerGoodPin, INPUT); // Set PWR_GOOD pin as input
  pinMode(ledPin, OUTPUT);      // Set LED pin as output
  digitalWrite(ledPin, LOW);    // Turn off LED initially
  Serial.begin(9600);           // Initialize serial communication
}

void loop() {
  int powerStatus = digitalRead(powerGoodPin); // Read PWR_GOOD pin status

  if (powerStatus == HIGH) {
    // Power is stable, turn off LED
    digitalWrite(ledPin, LOW);
    Serial.println("Power is stable.");
  } else {
    // Power is unstable, turn on LED
    digitalWrite(ledPin, HIGH);
    Serial.println("Power is unstable! Running on battery.");
  }

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

1. UPS Not Switching to Battery Power

   • Cause: Battery is not connected or is discharged.
   • Solution: Verify the battery connections and ensure the battery is charged.

2. Output Voltage Drops Below 5V

   • Cause: Load exceeds the maximum output current or battery is low.
   • Solution: Reduce the load or replace/charge the battery.

3. Battery Overheating During Charging

   • Cause: Faulty battery or inadequate ventilation.
   • Solution: Replace the battery and ensure proper ventilation.

4. CHG_IND or PWR_GOOD Pins Not Responding

   • Cause: Incorrect wiring or damaged pins.
   • Solution: Check the connections and test the pins with a multimeter.

Q1: Can I use the 5V UPS with a 3.3V device?
A1: No, the 5V UPS is designed to provide a stable 5V output. Use a voltage regulator or level shifter for 3.3V devices.

Q2: How long will the UPS run on battery power?
A2: The runtime depends on the battery capacity and the power consumption of the connected load. For example, a 2000mAh battery powering a 500mA load will last approximately 4 hours.

Q3: Can I charge the battery while the UPS is powering a device?
A3: Yes, most 5V UPS modules support simultaneous charging and powering of the load.

Q4: Is the UPS compatible with solar panels?
A4: Yes, as long as the solar panel provides a stable 5V output within the input voltage range of the UPS.