How to Use MW LRS-350-12: Examples, Pinouts, and Specs

The MW LRS-350-12 is a high-performance 12V DC switching power supply manufactured by MEAN WELL. It delivers a maximum output current of 29A, providing up to 350W of power. Designed for reliability and efficiency, this power supply is ideal for a wide range of applications, including powering LED lighting systems, industrial automation equipment, and other devices requiring stable and regulated DC power.

Key features of the LRS-350-12 include:

• Compact and lightweight design for easy integration.
• High efficiency of up to 89%.
• Built-in protections against overvoltage, overcurrent, and short circuits.
• Convection-cooled operation for silent performance.

• LED lighting systems (e.g., LED strips, signage, and displays).
• Industrial automation and control systems.
• Test and measurement equipment.
• DIY electronics projects requiring a stable 12V DC power source.

The LRS-350-12 features screw terminal connections for input and output. Below is the pin configuration:

1. Input Connection:

   • Connect the AC input terminals (L and N) to a suitable AC power source (85-264VAC).
   • Ensure the FG terminal is connected to earth ground for safety.

2. Output Connection:

   • Connect the V+ terminal to the positive input of your load.
   • Connect the V- terminal to the ground of your load.
   • Use appropriately rated wires to handle the maximum output current (29A).

3. Voltage Adjustment:

   • If necessary, use the V ADJ potentiometer to fine-tune the output voltage within ±10% of 12V (10.8V to 13.2V).

4. Power On:

   • After verifying all connections, power on the AC input. The power supply will provide a stable 12V DC output.

• Cooling: Ensure adequate ventilation around the power supply to prevent overheating. Avoid enclosing the unit in a sealed space without airflow.
• Load Requirements: Do not exceed the maximum output current of 29A or the total power rating of 350W.
• Safety: Always disconnect the power supply from the AC source before making any wiring changes.
• Protection Features: The LRS-350-12 includes built-in protections. If the power supply shuts down due to overvoltage, overcurrent, or short circuit, resolve the issue before restarting.

The LRS-350-12 can be used to power an Arduino UNO and other peripherals. Below is an example circuit and code:

1. Connect the V+ terminal of the LRS-350-12 to the VIN pin of the Arduino UNO.
2. Connect the V- terminal of the LRS-350-12 to the GND pin of the Arduino UNO.
3. Ensure the output voltage is set to 12V using the V ADJ potentiometer.

// Example code to blink an LED connected to pin 13 of the Arduino UNO
// Ensure the Arduino is powered by the LRS-350-12 (12V DC input).

void setup() {
  pinMode(13, OUTPUT); // Set pin 13 as an output
}

void loop() {
  digitalWrite(13, HIGH); // Turn the LED on
  delay(1000);            // Wait for 1 second
  digitalWrite(13, LOW);  // Turn the LED off
  delay(1000);            // Wait for 1 second
}

1. Can the LRS-350-12 be used with a battery?

   • No, the LRS-350-12 is designed for AC input only. It cannot be directly connected to a battery.

2. What is the maximum wire gauge recommended for connections?

   • Use wires rated for at least 30A for the output terminals to handle the maximum current safely.

3. Can the output voltage be adjusted beyond 12V?

   • Yes, the output voltage can be adjusted within a range of 10.8V to 13.2V using the V ADJ potentiometer.

4. Is the LRS-350-12 suitable for outdoor use?

   • No, the LRS-350-12 is not weatherproof. It should be used in a dry, indoor environment.

5. What happens if the load exceeds 29A?

   • The power supply will activate overcurrent protection and shut down to prevent damage. Reduce the load and restart the power supply.

This concludes the documentation for the MW LRS-350-12. For further assistance, refer to the official MEAN WELL datasheet or contact technical support.