How to Use bl 51: Examples, Pinouts, and Specs

The BL 51, manufactured by LG, is a low-power, high-efficiency LED driver designed to power LED arrays in a wide range of applications. It provides a constant current output, ensuring optimal performance and longevity of connected LEDs. The BL 51 is ideal for applications requiring energy-efficient lighting solutions, such as residential lighting, commercial displays, and automotive lighting systems.

• Residential and commercial LED lighting
• Automotive interior and exterior lighting
• LED signage and displays
• Industrial lighting systems

The BL 51 is housed in a compact SOT-23-6 package. Below is the pin configuration:

1. Power Supply: Connect a DC power supply (6V to 24V) to the VIN pin and GND pin.
2. LED Connection: Connect the positive terminal of the LED array to the LED+ pin and the negative terminal to the LED- pin.
3. Enable Pin: To activate the driver, apply a high signal (logic level) to the EN pin. Pulling this pin low will disable the driver.
4. Dimming Control:
   • For PWM dimming, apply a PWM signal (frequency range: 100Hz to 10kHz) to the DIM pin.
   • For analog dimming, apply a DC voltage (0V to 2.5V) to the DIM pin. A higher voltage corresponds to higher brightness.
5. Current Regulation: The BL 51 automatically regulates the current to 350mA, ensuring consistent LED brightness.

• Thermal Management: Ensure adequate heat dissipation, especially in high-power applications. Use a heatsink or place the component on a PCB with good thermal conductivity.
• Input Voltage: Do not exceed the maximum input voltage of 24V to avoid damaging the component.
• Dimming Signal: Ensure the dimming signal is within the specified range to prevent erratic behavior or damage.
• Bypass Capacitor: Place a bypass capacitor (e.g., 10µF) close to the VIN pin to stabilize the input voltage and reduce noise.

The BL 51 can be controlled using an Arduino UNO for PWM dimming. Below is an example circuit and code:

• Connect the VIN pin of the BL 51 to the 5V output of the Arduino.
• Connect the GND pin of the BL 51 to the GND of the Arduino.
• Connect the DIM pin of the BL 51 to a PWM-capable pin on the Arduino (e.g., Pin 9).
• Connect the LED array to the LED+ and LED- pins of the BL 51.

// Example code to control the BL 51 LED driver using PWM dimming
// Connect the DIM pin of the BL 51 to Pin 9 of the Arduino UNO

const int dimPin = 9; // PWM-capable pin connected to the DIM pin of BL 51

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

void loop() {
  // Gradually increase brightness
  for (int brightness = 0; brightness <= 255; brightness++) {
    analogWrite(dimPin, brightness); // Write PWM signal to DIM pin
    delay(10); // Small delay for smooth transition
  }

  // Gradually decrease brightness
  for (int brightness = 255; brightness >= 0; brightness--) {
    analogWrite(dimPin, brightness); // Write PWM signal to DIM pin
    delay(10); // Small delay for smooth transition
  }
}

1. Can the BL 51 drive multiple LEDs? Yes, the BL 51 can drive multiple LEDs connected in series, provided the total forward voltage does not exceed 20V.

2. What happens if the input voltage exceeds 24V? Exceeding 24V can permanently damage the BL 51. Always ensure the input voltage is within the specified range.

3. Can I use the BL 51 without dimming? Yes, the DIM pin can be left unconnected for full brightness operation.

4. What is the recommended PWM frequency for dimming? The recommended PWM frequency range is 100Hz to 10kHz for optimal performance.

By following this documentation, users can effectively integrate the BL 51 into their LED lighting projects and achieve reliable, energy-efficient performance.