Littelfuse LED Protectors

Littelfuse PLED Series is a voltage triggered electronic shunt device that provides a current bypass in the case of a single LED failing into an open circuit condition. When any single LED fails as an open circuit, PLED devices ensure that other LEDs within the string continue to function. PLED devices also protect against ESD (electrostatic discharge) and lightning surge effects. Designed to serve the needs of high brightness outdoor LED lighting applications (advertising and traffic signs, roadway/pathway/runway lighting, aircraft and emergency lighting, etc), PLED devices help assure reliability and lower maintenance requirements.

Littelfuse Delivers High Reliability, Low Maintenance, and Long-Term of LED Lighting Products

Below is an INTERACTIVE circuit diagram, CLICK the 5 green Application Solution links to see the product options to help you deliver the full benefits to your LED lighting solutions.

The light-emitting-diode (LED) lighting market is growing quickly, thanks in part to benefits of energy efficiency, long term life and durability, and low maintenance expectations.

A new problem that lighting system designers, product manufacturers, and end users are recognizing that, just like all electronics, LED strings and power sources are susceptible to damage by transient voltage, surges, and other electrical threats.

Particularly with outdoor applications, a common cause of LED failure is electrostatic-discharge (ESD) induced by nearby lightning strikes. Because these LEDs are used in traffic control and lighting, safety, and other critical use applications, failure is not an option.

PLED (Open LED Protector Series)

The new Littelfuse PLED Series provides added reliability to LED lighting designs by minimizing the impact due to the loss of a single LED in a series string of LEDs.

LED Protector - The open LED protector device (PLEDx) provides an electronic switching shunt path when a single or even multiple LEDs in the lighting string fails open. This insures the functionality of the remaining lighting array, thus providing for highly reliable lighting functions for applications such as roadside warning lights, streets lights, headlights, aircraft runways, etc. This PLED device is compatible with one, two, and three watt LEDs. It is available in two different surface mount packages, the standard DO-214AA and the Quad Flat Pak No-Lead (QFN). The QFN’s low profile, chip scale package (CPS) is ideal for dense board applications.

Features of PLED (Open LED Protector)

  • 1-, 2-and 3-watt LED compatibility that have a nominal 3V forward characteristic
  • Automatic reset after power cycle
  • Compatible with PWM dimming speeds up to 10KHz
  • Available in DO-214 AA and Chip Scale QFN package
  • A single PLED may protect up to four high brightness LEDs, offering a lower cost option for enhanced reliability
  • Reverse battery / power supply polarity protection
  • Electrostatic discharge (ESD) protection

What are PLED devices, and how do they compare?

Littelfuse PLED open-LED protection devices are often incorporated into the circuit designs of high-power LEDs in applications such as roadway lights and outdoor LED advertising display signs.

PLED devices are connected in parallel with each LED in a series string. If one LED should fail open-circuit, then the PLED connected to it will turn on and carry the current that would have gone through the failed LED. This keeps the rest of the string operating, and only a single LED goes dark instead of the whole string.

In the off state, a PLED draws only a few microamps, and thus, it does not affect the circuit. When triggered, it carries the full current of the string with a voltage drop of about 1.3 volts.

The PLED device helps protect the LED from surges induced by nearby lightning strikes and ESD events. In addition, the PLED contains reverse current diodes that will protect the LED string if the power supply is connected with reverse polarity.

PLED devices are typically connected across each LED in a string. However, units are available to connect across two or even three LEDs. While this reduces the cost of protection, it does cause more than one LED to go dark if one fails.

How do they compare to other circuit protection technologies?

  • A PLED provides open LED protection; While an SCR does as well, a Zener does not, because string current will overload it and shorten its life.
  • A PLED provides reverse polarity protection. An SCR and Zener will not.
  • A PLED and a Zener both provide ESD/lightning protection, but an SCR does not.
Features PLED SCR Zener Diode
LED open circuit protection Yes Yes No
Reverse polarity protection Yes No No
ESD/Lightning/EFT protection Yes No Yes
Response time ~100ns ~5µs -
Major disadvantages   Large device size

Typically requires a resistive voltage divider network to set the trigger voltage

Variation of triggering voltage versus temperature is quite large

Reverse blocking voltage is too high and so cannot provide reverse polarity protection
When an LED becomes open circuited, the Zener diode must conduct all of the curent. The Zener diode is not rated for this and so its life will be short.

Why do I need to use LED protectors

LEDs are often designed to connect in strings of five to twenty in series. Often the failure of any single LED will take out an entire string.

In street light or airport runway light applications, the loss of the string may dim or shut down the light, creating a safety hazard. In outdoor LED display advertising signs, it may produce blank spots and result in lost revenue.

In any case, the failure of an LED string is often a costly maintenance issue in outdoor applications.

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PLED


Digi-Key P/N Manufacturer P/N Description Package/Case Packaging
F3574TR-ND PLED5HT LED PROTECTOR 5V BI-DIR SOT-89 TO-243AA Tape & Reel (TR)
F3574CT-ND Cut Tape (CT)
F3574DKR-ND Digi-Reel®
F3575TR-ND PLED5Q12 LED PROTECTOR 5V BI-DIR 2X2 QFN

2-VQFN

Tape & Reel (TR)
F3575CT-ND Cut Tape (CT)
F3575DKR-ND Digi-Reel®
F5814TR-ND
PLED6M
LED PROTECTOR 6V BI-DIR PM-1 POWERMITE®* Tape & Reel (TR)
F5814CT-ND Cut Tape (CT)
F5814DKR-ND Digi-Reel®
F6298TR-ND
PLED6UQ12
LED PROTECTOR 6V UNI-DIR QFN 3X3 2-TDFN Tape & Reel (TR)
F6298CT-ND Cut Tape (CT)
F6298DKR-ND Digi-Reel®
F4111TR-ND PLED6Q12 LED PROTECTOR 6V BI-DIR QFN 3X3 2-TDFN Tape & Reel (TR)
F4111CT-ND Cut Tape (CT)
F4111DKR-ND Digi-Reel®
F6294TR-ND
PLED6US
LED PROTECTOR UNI-DIR 6V DO214 2L DO-214AA, SMB Tape & Reel (TR)
F6294CT-ND Cut Tape (CT)
F6294DKR-ND Digi-Reel®
F3277TR-ND PLED6S LED PROTECTOR 6V BI-DIR DO-214 DO-214AA, SMB Tape & Reel (TR)
F3277CT-ND Cut Tape (CT)
F3277DKR-ND Digi-Reel®
F6277TR-ND
PLED6SW
LED PROTECTOR 9V BI-DIR DO214 2L (WHITE BODY) DO-214AA, SMB Tape & Reel (TR)
F6277CT-ND Cut Tape (CT)
F6277DKR-ND Digi-Reel®
F6299TR-ND
PLED9UQ12
LED PROTECTOR 9V UNI-DIR QFN 3X3 2-TDFN Tape & Reel (TR)
F6299CT-ND Cut Tape (CT)
F6299DKR-ND Digi-Reel®
F4112TR-ND PLED9Q12 LED PROTECTOR 9V BI-DIR QFN 3X3 2-TDFN Tape & Reel (TR)
F4112CT-ND Cut Tape (CT)
F4112DKR-ND Digi-Reel®
F6295TR-ND
PLED9US
LED PROTECTOR 9V UNI-DIR DO-214 2L DO-214AA, SMB Tape & Reel (TR)
F6295CT-ND Cut Tape (CT)
F6295DKR-ND Digi-Reel®
F3278TR-ND PLED9S LED PROTECTOR 9V BI-DIR DO-214 DO-214AA, SMB Tape & Reel (TR)
F3278CT-ND Cut Tape (CT)
F3278DKR-ND Digi-Reel®
F6278TR-ND
PLED9SW
LED PROTECTOR 9V BI-DIR DO214 2L (WHITE BODY) DO-214AA, SMB Tape & Reel (TR)
F6278CT-ND Cut Tape (CT)
F6278DKR-ND Digi-Reel®
F6300TR-ND
PLED13UQ12
LED PROTECTOR 13V UNI-DIR QFN 3X3 2-TDFN Tape & Reel (TR)
F6300CT-ND Cut Tape (CT)
F6300DKR-ND Digi-Reel®
F4110TR-ND PLED13Q12 LED PROTECTOR 13V BI-DIR QFN 3X3 2-TDFN Tape & Reel (TR)
F4110CT-ND Cut Tape (CT)
F4110DKR-ND Digi-Reel®
F6296TR-ND
PLED13US
LED PROTECTOR 13V UNI-DIR DO-214 2L DO-214AA, SMB Tape & Reel (TR)
F6296CT-ND Cut Tape (CT)
F6296DKR-ND Digi-Reel®
F3279TR-ND PLED13S LED PROTECTOR 13V BI-DIR DO-214 DO-214AA, SMB Tape & Reel (TR)
F3279CT-ND Cut Tape (CT)
F3279DKR-ND Digi-Reel®
F6275TR-ND
PLED13SW
LED PROTECTOR 13V BI-DIR DO214 2L (WHITE BODY) DO-214AA, SMB Tape & Reel (TR)
F6275CT-ND Cut Tape (CT)
F6275DKR-ND Digi-Reel®
F6301TR-ND
PLED18UQ12
LED PROTECTOR 18V UNI-DIR  3X3 QFN 2-TDFN Tape & Reel (TR)
F6301CT-ND Cut Tape (CT)
F6301DKR-ND Digi-Reel®
F3577TR-ND PLED18Q12 LED PROTECTOR 18V BI-DIR 3X3 QFN 2-TDFN Tape & Reel (TR)
F3577CT-ND Cut Tape (CT)
F3577DKR-ND Digi-Reel®
F6297TR-ND
PLED18US
LED PROTECTOR 18V UNI-DIR DO-214 2L DO-214AA, SMB Tape & Reel (TR)
F6297CT-ND Cut Tape (CT)
F6297DKR-ND Digi-Reel®
F3576TR-ND PLED18S LED PROTECTOR 18V BI-DIR DO-214 DO-214AA, SMB Tape & Reel (TR)
F3576CT-ND Cut Tape (CT)
F3576DKR-ND Digi-Reel®
F6276TR-ND
PLED18SW
LED PROTECTOR 18V BI-DIR DO214 2L (WHITE BODY) DO-214AA, SMB Tape & Reel (TR)
F6276CT-ND Cut Tape (CT)
F6276DKR-ND Digi-Reel®

 

*POWERMITE® is a registered trademark of Microsemi Corporation.

 




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