High-performance outdoor LED lighting protection solution

As the cost of LEDs continues to drop, and governments around the world are paying more and more attention to energy conservation and environmental protection, the market prospects for LED lights are becoming increasingly broad. High-brightness LED lights have appeared in a variety of occasions, from outdoor billboards, TV LED backlights to traffic lights, airport runway navigation lights, etc. The advantages of LED lights are also particularly prominent, such as long life, high energy efficiency and rich colors.

However, the first thing LED lamp designers must consider is the reliability of the lamp. For many occasions, the importance of reliability is self-evident: for example, some outdoor lighting with high maintenance costs, and some applications that are prone to safety hazards, including traffic lights, navigation lights, etc. LED is also a fragile semiconductor solid-state device. Its light-emitting principle is that the forward voltage bias of the PN junction of the diode produces a light source. Both LED arrays and power supplies are at risk of being damaged by transient voltages, surge currents and other electronic problems. Especially in outdoor lighting applications, electrostatic discharge (ESD) caused by nearby lightning strikes can easily cause LED failures. As a leading global manufacturer and solution provider of protection devices, Littelfuse has a wide range of optional products that can provide high-performance LED protection solutions for the above threat sources.

Power supply protection scheme

In the switching power supply part, LF recommends the following overcurrent and overvoltage protection solutions:

TVS Tube

AK6 and AK10 series are transient voltage suppressors (TVS) with extremely high rated current, specially designed to protect AC and DC input circuits from transient voltage damage, with ratings of 6kA (8x20us) and 10kA (8x20us); 15KPA and 30KPA are TVS rated at 15,000 W and 30,000 W respectively, both of which are ideal for protecting LED lighting in harsh environments. 1.5SMC series is a TVS rated at 1500W, which is ideal for protecting DC-DC converters from transient voltage damage.

TMOV Thermal Protection Varistor

TMOV integrates thermal components, helping TVSS modules meet UL1449 standards for cable-attached and permanent-attached applications using appropriate enclosures. TMOV offers faster thermal response and lower inductance than most discrete solutions, resulting in improved clamping performance for fast response to voltage transients.

As the cost of LEDs continues to drop, and governments around the world are paying more and more attention to energy conservation and environmental protection, the market prospects for LED lights are becoming increasingly broad. High-brightness LED lights have appeared in a variety of occasions, from outdoor billboards, TV LED backlights to traffic lights, airport runway navigation lights, etc. The advantages of LED lights are also particularly prominent, such as long life, high energy efficiency and rich colors.

However, the first thing LED lamp designers must consider is the reliability of the lamp. For many occasions, the importance of reliability is self-evident: for example, some outdoor lighting with high maintenance costs, and some applications that are prone to safety hazards, including traffic lights, navigation lights, etc. LED is also a fragile semiconductor solid-state device. Its light-emitting principle is that the forward voltage bias of the PN junction of the diode produces a light source. Both LED arrays and power supplies are at risk of being damaged by transient voltages, surge currents and other electronic problems. Especially in outdoor lighting applications, electrostatic discharge (ESD) caused by nearby lightning strikes can easily cause LED failures. As a leading global manufacturer and solution provider of protection devices, Littelfuse has a wide range of optional products that can provide high-performance LED protection solutions for the above threat sources.

Power supply protection scheme

In the switching power supply part, LF recommends the following overcurrent and overvoltage protection solutions:

TVS Tube

AK6 and AK10 series are transient voltage suppressors (TVS) with extremely high rated current, specially designed to protect AC and DC input circuits from transient voltage damage, with ratings of 6kA (8x20us) and 10kA (8x20us); 15KPA and 30KPA are TVS rated at 15,000 W and 30,000 W respectively, both of which are ideal for protecting LED lighting in harsh environments. 1.5SMC series is a TVS rated at 1500W, which is ideal for protecting DC-DC converters from transient voltage damage.

TMOV Thermal Protection Varistor

TMOV integrates thermal components, helping TVSS modules meet UL1449 standards for cable-attached and permanent-attached applications using appropriate enclosures. TMOV offers faster thermal response and lower inductance than most discrete solutions, resulting in improved clamping performance for fast response to voltage transients.

Fuse

The AC line fuse uses the 464 series, which provides a minimized, fast-response surface-mount 250VAC fuse that complies with the IEC60127-4 standard. The 464 is specifically designed for power supply and lighting system design applications.

High-voltage DC fuses can be selected from the 477 or 505 series. Both series are designed for high-energy and power applications. The 477 series provides 400VDC/500VDC rated voltage, time-delay, and surge-resistant fuses in a 5x20mm package; the 505 series provides 500VAC/VDC rated voltage fuses with an upper interruption rating of up to 50kA in a 6.3 x 32mm package.

LED array partial protection solution: PLED open circuit protector

The above solution can effectively deal with the surge threat generated by the power supply part and protect the LED from damage. However, we all know that LED lights are usually composed of a certain number of LED tubes connected in series or in parallel to form an array. The damage of a single LED will cause the entire LED array to stop working. Traditional fuses, MOVs, and TVS cannot guarantee such problems. Therefore, at the LED array end, LF has developed a PLED LED open circuit protector specifically for LED open circuits, as shown in the figure:

PLED LED open circuit protector

The PLED series is a voltage-triggered switch-on element, which is used as a bypass in series with the LED lamp in the circuit. When the LED is open, the voltage drops to the PLED. Then, the PLED is activated and turned on. This shunt path bypasses the open LED and allows current to flow into other LEDs in the series circuit, thereby eliminating the impact caused by the damage of a certain LED and improving the stability of the LED lighting design. PLED can protect up to 4 high-brightness LEDs at the same time, providing strong protection at a lower cost. It is mainly suitable for 1W, 2W, 3W and other high-brightness LED lamps, with a maximum current of 1000mA.

Compared with traditional LED protection solutions, Littelfuse PLED devices can provide a simpler and more economical circuit design. Its features and advantages include:

1. Ensure the entire LED string continues to work when one LED is damaged

2. Available in DO-214AA, chip-level QFN and Powermite packages

3. Can protect up to 4 high-brightness LED tubes, providing strong protection at a lower cost

4. Two-in-one protection (open circuit fault protection, and additional surge and ESD protection)

5. The protection action will not cause any negative impact on the power supply

6. Reverse connection protection function

7. Compatible with 10KHz PWN dimming speed

8. Automatic reset after LED open circuit recovery

Conclusion

Littelfuse's high reliability and low maintenance outdoor LED lighting overall protection solutions have greatly reduced the maintenance cost of LED lamps, extended their service life, and enhanced the brand value of the products. As the largest agent of Littelfuse in China, Asiacom is dedicated to providing customers with the most thoughtful technical support and supply services, creating more value for Chinese LED lamp manufacturers.