Understanding Why LED Signage Uses 12V Constant Voltage Drivers

When it comes to LED signages, one of the most intriguing cases is the use of constant voltage (CV) drivers at a specific voltage level, usually 12V. This configuration is prevalent primarily due to the inherent limitations of the signage applications and the flexibility it provides. In this article, we'll delve into the reasons behind this choice and explore the advantages and disadvantages of using 12V constant voltage LED drivers in signage.

Why 12V Constant Voltage LED Drivers?

The primary reason for using 12V constant voltage drivers in signages is the unpredictability of the module requirements. In a backlit glow sign or in characters, there's no way to predict the exact size of the sign, the number of modules needed, or the uniformity required for coverage without dark spots or hotspots. This makes it challenging to design a constant current (CC) driver that can cater to a wide range of loads efficiently.

Theoretical vs. Practical Considerations

Theoretically, one could design a constant current driver with a very high voltage, say 210V DC, and connect 10 to 70 LEDs. However, the current drawn would vary significantly depending on the load, leading to uneven illumination where certain sections might be brighter or dimmer than others. This inconsistency is unacceptable in signage applications.

Moreover, very high voltages pose safety risks, especially concerning electric shock. This is why a more practical and safer approach is to use a constant voltage driver with a relatively lower voltage, such as 12V. A 12V SMPS (Switched Mode Power Supply) conventional type ensures that the output is maintained constant regardless of the load changes or mains voltage fluctuations. This makes it easy to add more LED modules in parallel until the current capacity of the driver is fully utilized.

Practical Advantages

The practical and convenient nature of 12V constant voltage setup allows for easy scalability. You can add as many LED modules as needed in parallel without worrying about the current draw. This setup is especially useful in dynamic signage where the number of illuminated modules can vary.

However, there is a trade-off. This convenient arrangement comes with a reduction in energy efficiency. In this setup, a significant amount of power is wasted in the resistors, which act as simple current limiters. Approximately 25% of the power, calculated as 3V/12V, is dissipated in the resistor. While this is less efficient, it is a small price to pay for the flexibility and convenience it offers.

Alternative Approaches

For most LED lighting applications where the load is well-defined and fixed, dedicated constant current drivers are preferred. These drivers provide the exact current required by the LEDs, ensuring uniform and reliable performance without the need for additional components like resistors.

Energy Efficiency vs. Flexibility

It's important to note that while the 12V constant voltage setup offers convenience, it sacrifices some energy efficiency. Running LEDs in series with a current source is more efficient as the LEDs share the current, but this approach is more sensitive to any breaks in the circuit. Additionally, adding more LEDs in series means ensuring they all have the same current rating, which can be difficult to achieve in practice.

In comparison, the parallel setup with a voltage source can be powered by solar energy or battery, making it more flexible and simple to manage. This is particularly beneficial for outdoor or off-grid signage applications where a direct power source is available and easy to manage.

Conclusion

In summary, the choice of 12V constant voltage drivers in LED signages is driven by practical considerations and the need for flexibility in scaling the number of modules. While this setup comes with a power loss in resistors, it provides a reliable and simple solution for a wide range of applications. Understanding the trade-offs between energy efficiency and flexibility helps in making informed decisions when designing LED signages.

For more information and specific guidance, feel free to reach out to LEDchip Indus P Ltd, a wholly Indian effort in the UJALA mission to save trillions of watts of power in India. Their expertise in LED technology and efficiency can provide valuable insights and solutions for your LED signage needs.

Contact Information

Detailed information and contact details for LEDchip Indus P Ltd can be found on their website or through this link.