LM-80 Testing Solutions

Vektrex offers complete LM-80 test solutions that meet all IESNA and Energy Star testing criteria. Vektrex actively participates on the LM-80 committee, chairing the LM-80 working group developing the LM-80 methods and moving this standard through the acceptance process and into IEEE acceptance.

VEKTREX LM-80 Testing Solutions

VEKTREX offers complete solutions for reliability testing and measuring luminous flux and color maintenance for Lasers and LED packages, arrays, and modules

High-capacity VEKTREX LM-80 Systems combine spike-protected, constant or pulsed current LED drive electronics with fully integrated thermal control systems and automated light measurement. Vektrex LM-80 Systems are optimized for LM-80-08 and LM-80-15 compliance testing for low, mid and high power LEDs, modules, COBs, and arrays operating in infrared, visible, or UV. Vektrex LM-80 Systems are also applicable for use with laser diodes.

THE LM80-21 guidelines, based upon over two dozen changes to the previous LM-80-15 guidelines, update testing procedures and factor in the performance characteristics of UV-LEDs, and lasers/laser-diodes.

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Industry-Leading Drive Electronics

Energy-efficient VEKTREX SpikeSafe™ Series current sources supply DC and precision-pulsed drive current up to 50A at voltages up to 400V for LM-80 testing and high-power LED reliability stress applications. Multiple-source channel modules deliver high capacity and high power density with the testing flexibility of independent channel control. SpikeSafe™ load protection continuously monitors voltage and current on all source channels and instantly shuts down when device anomalies are detected. Rapid shutdown preserves the failure device for analysis, protects other devices, reduces failure counts, and improves reliability results.

High-Capacity Thermal Control

Temperature uniformity is essential to successful LM-80 testing. Vektrex Integrated Thermal Control Systems (ITCS) use plant chill water and a closed loop system for uniform thermal control in a compact, energy-efficient footprint. With up to 10kW of power handling capability – at operating temperatures up to 150C – the Vektrex ITCS provides the capacity to test numerous high power devices in a single chamber. Integrated fixturing with convenient slide-out drawers simplify loading and unloading. Available individual drawer temperature controls allow side-by-side testing of multiple device types with different thermal characteristics.

Repeatable Light Measurement

The Vektrex Automated Light Measurement System integrates thermal control and precise electrical and optical instrumentation with easy-to-use software tools for measuring and recording LM-80 photometric and electrical test results. Single pulse, DC and continuous pulse modes are compliant with LM-85 requirements for repeatable high power LED light measurement. With 0.05% flux repeatability, the Vektrex Automated Light Measurement System can detect LED test trends within hours.

Comprehensive Test Software

Vektrex software applications are designed to address and support a wide range of testing needs. The LM-80 software suite includes STARS testing and monitoring software that controls and monitor source channels, loads, and thermal control devices during testing. STARPLOT software application graphically presents a view of reliability data generated by STARS. STARPLOT provides a graphical view of reliability data where defects such as internal shorts in LED arrays, connector wear, and even thermal problems may be identified. From plotting data and identifying trends to failsafe protection and remote thermal control, Vektrex software simplifies test control and accurate data collection.

Confidence

Whether you’re expanding existing test capacity, or stepping up to higher-power LM-80 LED testing systems, Vektrex systems and components give you the flexibility to scale a wide range of LED testing configurations. Leading manufacturers and LM-80 labs worldwide rely on Vektrex systems and components for unmatched power, capacity, and reliable performance.

What is LM-80-21

LM-80-21 is the latest IESNA release documenting requirements for LM-80 testing. An informative presentation given to CORM may be downloaded from Vektrex info page.

Key LM-80 Testing Requirements

Key LM-80 Requirements	Vektrex Exceeds the Requirements
Constant Current Drive (DC Mode) PWM Drive / Pulsed Current Accuracy < 3%	SpikeSafe™ Protected Modular Current Sources, available to 400V, 50A DC and Precision Pulsing Individual Source Channel Control Typical Current Accuracy 0.1% MTBF 175,000 Hours
Accurate Time Keeping Typically 6,000 – 10,000 Hours Duration DUT Failure Recording	Logs Data, Monitors Errors & Faults, Duration Timers, Data Visualization
Two or More Test Temperatures -2 to ∞ Case Temperature Control -5 to ∞ Air Temperature Control	to 150C Operation, 0.2C Stability, up to 10kW / Chamber Load UV, IR, VIS, & Array Device Support
Spectrometer-based Measurements Selectable Measurement Temperature	Automatically Tests up to 80 DUTs Repeatable to 0.05% Flux Measurement LM-85 Capable
Test Timing Uncertainty Analysis	Numerous NVLAP Certified Installations LM-80 Training

What is LM-80 Testing?

Lumen maintenance applies to a range of testing methods used to evaluate light sources and predict the device lifetime. These light sources degrade gradually until they no longer provide sufficient output. A standardized report is output from the lumen maintenance tests. The standards report allows users for these light devices to select the appropriate light source for their application, guarantee their products based upon the data, and reduce risk for excessive support and maintenance.

Approved by the Illuminating Engineering Society of North America (IESNA) and accepted worldwide, LM-80 is a testing method that evaluates how long LED and Laser modules or chips will output adequate light. While manufacturers previously deployed a series of testing methods, LM-80 documents are more uniform test method based upon duration and temperature – one that examines and establishes lumen output and color shift.

Between the two factors; test duration and temperature

LM-80 testing determines how soon and what rate the light source will depreciate, factoring in outside factors like temperature that could accelerate the timeframe.
Color shift examines how much and to what degree the color of light generated will change. Also called chromaticity shift, this test determines when the light will shift from white to red, also factoring in an accelerated timeframe in reference to temperature.
LM-80 testing does not provide information about absolute output, light quality or energy efficiency of a source. Instead, LM-79 photometric testing is performed to gather this data.
LM-80 strictly applies to the LED or Laser array and module – not a full lamp or fixture. The data assists with selection of a light emitting devices for various applications.
LM-80 testing is required to obtain Energy Star Certification in the US and state-level certifications for commercial upgrades intended to reduce energy consumption.

What is TM-21?

TM-21 testing is used in conjunction with LM-80 testing. Once at least 6,000 hours of LM-80 testing has been completed with light measurements taken at the required intervals, TM-21 testing is applied to asses further lumen degradation, basing its results on exsisting data and tracking the devices projected performance up to at least 36,000 hours (and more with extended LM-80 testing). This combined data provides a more thorough picture of an LEDs light output over time and helps manufacturers refine performance.

💡 LM-80 Brochure
💡 ITCS Brochure
💡 Drive Electronics Brochure
💡 Bulk Power Cabinet
💡 STARS Datasheet

💡 Python API and Examples
💡 STARS
💡 STARPLOT

LM-80-21 (2022) Changes

Scope expanded to include lasers and UV LEDs.
Filament lamps are not added since they are better tested as finished products.Working group tasked to add laser diodes and filament LED lamps to the LM-80 standard.
Definitions updated to be more consistent and easy to understand
Ts point is now called TMP temperature; it maybe a point external to the package.
TMP temperature location must be documented with image or drawing. This allows the test to be duplicated at another location; it also allows a comparison measurement in a luminaire to use the same location.
Thermal modeling eliminated as a way to monitor TMP temperature.
Air is now the required atmosphere. LM-80 tests can no longer be performed in spectral atmospheres like helium.
Extrapolation in other documents should be reviewed. TM-21 and other documents should be reviewed prior to commencing testing to ensure measurement intervals, test duration, etc. will meet those requirements
Optical measurements must now capture 98% of light. The DUT must now be coupled to the sphere to capture 98% of the DUT’s light output. A goniospectroradiometer may also be used.
A self-absorption is required at each measurement interval. The self-absorption corrects for changes in the load board housing the DUTs
Chromaticity measurements may use CIE 1976 (uprime, vprime) or CIE 1931 (x, y). The automotive industry uses x,y exclusively.
DUTs may be classified as failures if Vf or If shifts by 50%. This allows test labs to remove DUTs that cannot be driven due to excessively high compliance.
Data reporting clarified. Normalized measurements are now specifically allowed. Chromaticity measurements are clarified. These changes align LM-80 with typical laboratory practice.
LED failure type must be reported. Type of failure (i.e. mechanical, electrical, or optical)
IES TM-27 Spectral Power Distribution added as an optional item to support future use of data for other research applications.
Informative annex on testing COB devices added. The annex discusses best practices for testing COB devices.
Informative annext on laboratory best practices added. The annex discusses various practices contributed by working group members.
Jeff Hulett, Vektrex, chairs their working group.

LM-80-15 (2015) Changes

Scope expanded to include radiant, photon or luminous flux maintenance
Air temperature control required (shall)
Alternate temperature sensor acceptable (RTD, Thermocouple, Thermistor)
Case temperature taken at manufacturers designated measurement point
Any light measurement temperature may be used
Specific methods for monitoring case temperature
All DUTs shall be tracked
No seasoning or aging prior to test
Drive types expanded to include PWM, AC Regulated Voltage, Constant Voltage
Eliminate ripple and total harmonic distortion requirements

LM-80-08 Addendum (2012)

Test temperatures reduced to two, one of which must be 55C or 85C
Different currents may be used at the different test temperatures
Interpolation per TM-21 to predict luminous flux maintenance requires the same drive current for the two temperatures
Testing at three or more temperatures offers more accurate interpolations

Key LM-80-08 (2008)/Energy Star Testing Requirements;

Minimum 20 device test lot per device family
Minimum 10 device test lot for modules
Constant Current (DC mode) only
Current accuracy better than 3%
Three Test Temperatures: 55C, 85C, and one other selected by the manufacturer
Thermocouples MUST be used for temperature measurement (special limits wire)
Case temperature shall be maintained at a temperature greater than or equal to 2C below the test temperature
Air temperature should be maintained at a temperature greater than or equal to 5C below the test temperature
Minimum 6,000 hours test time (10,000 recommended)
Light Measurements collected at T0 and generally every 1,000 hours.
Light Measurements taken at 25C.
Test Timing Uncertainty for the software application must be calculated to ensure minimum testing is achieved
RH less than 65%
Record Lumen Maintenance, Chromaticity, and Catastrophic failures
17025 Lab Certification
NVLAP Self Certification and LM-80 audit

The LM-80 standard is accepted worldwide. The intent is for LEDs and LED devices to be tested in several standardized operating conditions. The data resulting from LM-80 measurements are matrices of lumen maintenance values. LM-80 defines a standardized report output for the data.

LED manufacturers use this data to predict the LED light output over the life, improve their processes, and compare their devices with other competitor devices. Users of LEDs (for example Lighting Designers) use this standardized data to select the appropriate LEDs for their application and, in conjunction with TM21, to correctly define the warranty period. In the USA, LM-80 testing is required for Energy Star Certification.