How to Use MCP73831: Examples, Pinouts, and Specs

The MCP73831 is a highly integrated linear charge management controller for single-cell Lithium-Ion and Lithium-Polymer batteries. It is designed for space-limited and cost-sensitive applications, providing a simple and efficient solution for charging Li-ion/Li-Po batteries. The MCP73831 integrates current regulation, voltage regulation, charge termination, and charge status indication, making it ideal for portable electronics, such as smartphones, cameras, and personal media players.

• Portable electronic devices
• Wearable technology
• Bluetooth headsets and accessories
• Health and fitness monitors
• Backup power and energy storage solutions

• Charge Regulation Voltage: 4.2V
• Programmable Charge Current: 15mA to 500mA
• Input Voltage Range: 3.75V to 6.0V
• Operating Temperature Range: -40°C to +85°C
• Charge Status Output: Active High

1. Power Supply Connection: Connect a stable voltage source within the input voltage range (3.75V to 6.0V) to the VDD pin.
2. Battery Connection: Connect the positive terminal of the Li-ion/Li-Po battery to the VBAT pin.
3. Ground Connection: Connect the VSS pin to the ground of your power supply and battery.
4. Charge Current Setting: Connect a resistor from the PROG pin to ground to set the desired charge current. Use the formula I_charge = 1000V / R_PROG to calculate the resistor value.
5. Charge Status Indicator: The STAT pin can be connected to an LED with a current-limiting resistor to indicate the charging status or directly interfaced with a microcontroller.

• Ensure the power supply voltage does not exceed the maximum input voltage rating.
• Use a stable power source to avoid fluctuations that could affect the charging process.
• Select a charge current that is safe for your specific battery's charging specifications.
• Avoid placing the MCP73831 in environments that exceed its temperature specifications.
• Ensure proper thermal management to prevent overheating during operation.

• Battery Not Charging: Check the connections to the battery and ensure the input power supply is within the specified range.
• Overheating: Ensure the charge current is not set too high for the battery or the MCP73831's thermal limits.
• No Charge Status Indicator: Verify the STAT pin connection and the functionality of the charge status indicator circuit.

• Double-check all connections, especially the PROG resistor value and its soldering.
• Measure the input voltage and the voltage at the VBAT pin to ensure proper levels.
• If using an LED for charge status, confirm the LED and current-limiting resistor are correctly oriented and functioning.

Q: Can I charge a battery with a higher voltage than 4.2V using the MCP73831? A: No, the MCP73831 is designed for single-cell Li-ion/Li-Po batteries with a charge regulation voltage of 4.2V.

Q: How do I know if the battery is fully charged? A: The STAT pin will be deasserted (logic low) when the battery is fully charged.

Q: Can I use the MCP73831 to charge multiple batteries in series? A: No, the MCP73831 is intended for single-cell battery charging only.

Q: What should I do if the MCP73831 is getting too hot during operation? A: Check the charge current setting and ensure it is within the recommended range for both the battery and the MCP73831. Also, improve heat dissipation with proper PCB layout and possibly a heat sink.

// Example code to monitor the charge status of a battery using MCP73831 and Arduino UNO

const int chargeStatusPin = 2; // Connect the STAT pin of MCP73831 to digital pin 2

void setup() {
  pinMode(chargeStatusPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  int chargeStatus = digitalRead(chargeStatusPin);
  
  // Check if the battery is currently charging
  if (chargeStatus == HIGH) {
    Serial.println("Battery is charging...");
  } else {
    Serial.println("Battery is fully charged or not charging.");
  }
  
  delay(1000); // Wait for 1 second before checking again
}

This code sets up the Arduino to read the charge status from the MCP73831 and print a message to the Serial Monitor indicating whether the battery is charging or fully charged. Make sure to connect the STAT pin of the MCP73831 to digital pin 2 on the Arduino UNO.