1、JEDEC STANDARD Guidelines for Combining CIE 127-2007 Total Flux Measurements with Thermal Measurements of LEDs with Exposed Cooling Surface JESD51-52 APRIL 2012 JEDEC SOLID STATE TECHNOLOGY ASSOCIATION NOTICE JEDEC standards and publications contain material that has been prepared, reviewed, and app
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10、tact information. JEDEC Standard No. 51-52 -i- GUIDELINES FOR COMBINING CIE 127-2007 TOTAL FLUX MEASUREMENTS WITH THERMAL MEASUREMENTS OF LEDS WITH EXPOSED COOLING SURFACE CONTENTS Foreword. ii Introduction. ii 1 Scope. 1 2 Normative references 1 3 Terms, definitions, and notations 2 4 Recommended t
11、est environment for LEDs. 3 4.1 General recommendations for measuring the light output 4 4.2 Combined thermal and radiometric LED testing station 6 5 Data reporting . 8 6 Bibliography . 8 JEDEC Standard No. 51-52 -ii- GUIDELINES FOR COMBINING CIE 127-2007 TOTAL FLUX MEASUREMENTS WITH THERMAL MEASURE
12、MENTS OF LEDS WITH EXPOSED COOLING SURFACE Foreword This document has been prepared by the JEDEC JC-15 Committee on Thermal Characterization. It provides guidelines on the implementation of the light output measurement of power LEDs when used in combination with thermal characterization. Introductio
13、n This document is intended to be used in conjunction with the JESD51-50 series of standards, especially with JESD51-51 (Implementation of the Electrical Test Method for the Measurement of Real Thermal Resistance and Impedance of Light-emitting Diodes with Exposed Cooling Surface) document. This pre
14、sent document focuses on the measurement of the total radiant flux of LEDs in combination with the measurement of LEDss thermal characteristics: guidelines on the implementation of the recommendations of the CIE 127-2007 document are provided. Terms and definitions of the JESD51-53 (Terms, Definitio
15、ns and Units Glossary for LED Thermal Testing) document are used here in a way consistent with the relevant definitions of CIE the International Committee of Illumination, given in CIE S 017/E:2011 ILV, CIE 127:2007, CIE 84:1989, and other standards used in the solid-state lighting industry, e.g., A
16、NSI/IESNA RP-16-10. The reason why these guidelines are provided is that the physics determining LEDss light output characteristics is rather complex, which requires special care both in thermal characterization and during light output measurements. The need for measurement guidelines for LEDs has a
17、risen when light-emitting diodes with high power and high energy conversion efficiency emerged. Figure 1 The mutual dependence of LEDss light output and different (macroscopic) quantities characteristic to LEDss operating conditions : Light output IF: Forward current VF: Forward voltage PH: Dissipat
18、ed heating powerTJ: Junction temperature JEDEC Standard No. 51-52 -iii- Introduction (contd) This complexity in the physics as illustrated in Figure 1 becomes manifest in the following: Light output of LEDs is primarily determined by the recombination processes taking place in the pn-junction. The h
19、igher the ratio of the radiative recombination with respect to the non-radiative recombination, the more photons are generated, hence the electrical energy to light conversion efficiency of the LEDs is higher. This ratio is determined by the operating conditions of the LED: the junction temperature
20、and the applied forward current. This efficiency is not a single number because it depends both on the LEDs junction temperature and forward current (as shown in Figure 2). The power dissipated at the active region of an LED is thus determined by the difference between the supplied total electrical
21、energy (VF IF) and the total energy emitted as optical radiation (e emitted total radiant flux, also denoted as Popt): PH= VF IF e(1) This power together with the thermal resistance of the LED determines the junction temperature. For the end-users of the LEDs, the manifestation of this complex and t
22、emperature dependent physics of LEDss operation is the change of the properties of the emitted light: drop in the emitted luminous flux, shift of peak wavelength of the spectrum, and the change of the spectral power distribution of the emitted light (such as shown in Figure 3) resulting also in the
23、chnage of other characteristics of the emitted light. Figure 2 Temperature and forward current dependence of the energy conversion efficiency (also known as radiant efficiency) of a power LED (Popt/Pel emitted optical power / electrical power) 1000IFforward current mA100 200 400 500 700 80010 15 20
24、25 30 eradiant efficiency %Tref = 15oC Tref = 25oC Tref = 35oC Tref = 45oC Tref = 55oC Tref = 65oC 300 600 900 JEDEC Standard No. 51-52 -iv- Introduction (contd) Spectral distribution of light output of a 1W red LED at different current levels and different temperatures00.0020.0040.0060.0080.010.012
25、570 584 598 611 625 638 652 665 678 692 705 719Wavelength nmSpectralintensity W/nmT25_I200T25_I500T50_I200T50_I500T75_I200T75_I500Figure 3 Temperature dependence of spectral distribution of the light output a red LED at different current levels JEDEC Standard No. 51-52 Page 1 GUIDELINES FOR COMBININ
26、G CIE 127-2007 TOTAL FLUX MEASUREMENTS WITH THERMAL MEASUREMENTS OF LEDS WITH EXPOSED COOLING SURFACE (From JEDEC Board Ballot JCB-12-09, formulated under the cognizance of the JC-15 Committee on Thermal Characterization.) 1 Scope These guidelines specify testing procedures and conditions for power
27、light-emitting diodes (power LEDs) and/or high brightness light-emitting diodes (HB LEDs) in the following referred to as LEDs which are typically used in the operating regime of the forward current of 100mA and above, and emit visible light1). The application of these guidelines is recommended for
28、packaged LEDs 1. with a total electrical power consumption above 0.5 W, 2. which have energy conversion efficiency above 5%, 3. that are measured and considered as a single light source. This document is restricted to LEDs which have an exposed cooling surface. Guidelines provided here refer to labo
29、ratory measurements. Issues of high speed bulk measurements of LEDs (such as in-line testing aimed for, e.g., binning) are dealt with by other standardization bodies such as the relevant technical committees of CIE. Recommendations given in this document are valid for LEDs powered by DC forward curr
30、ent only. Measurement issues of AC power driven LEDs will be dealt with in future documents. 2 Normative references The following normative documents contain provisions that, through reference in this text, constitute provisions of this guideline. For dated references, subsequent amendments to, or r
31、evisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative docume
32、nt referred to applies. JESD51-50, Overview of Methodologies for the Thermal Measurement of Single- and Multi-Chip, Single- and Multi-PN-Junction Light-Emitting Diodes (LEDs). JESD51-51, Implementation of the Electrical Test Method for the Measurement of Real Thermal Resistance and Impedance of Ligh
33、t-emitting Diodes with Exposed Cooling Surface. JESD51-53, Terms, Definitions and Units Glossary for LED Thermal Testing. CIE S 017/E:2011 ILV, International Lighting Vocabulary. 1)Strictly speaking, the term LED should only be applied to those diodes which emit visible light. Those, which emit infr
34、a red or UV radiation, should be referred to as IR LEDs or UV LEDs and are not dealt with in this document. JEDEC Standard No. 51-52 Page 2 2 Normative references (contd) CIE 127:2007, Technical Report, Measurement of LEDs, ISBN 978 3 901 906 58 9. CIE 84:1989, Technical Report, The measurement of l
35、uminous flux, ISBN 978 3 900734 21 3. ANSI/IESNA IES Nomenclature Committee, IES RP-16-10, Nomenclature and Definitions of for Illuminating Engineering, ISBN 978-0-87995-208-2 3 Terms, definitions, and notations In this document the notations used in JESD51-50, which is the overview document for the
36、 JESD51-51 through JESD51-53 series of standards, and in JESD51-51 are applied. Generic terms and quantities related to light output measurement are used as defined in the International Lighting Vocabulary, CIE S 017/E:2011; LED specific terms of photometry and radiometry given in CIE 127:2007are al
37、so used. The most important terms and notations referred to in the series of LED thermal testing documents are listed in Table 1. For terms and definitions not listed below refer to JESD51-53. Table 1 Symbols used in this document Symbol Unit of measure Name, description TJoC junction temperature of
38、 the LED as defined in JESD51-50 and JESD51-51, denoted and referred to in CIE 127:2007 as TC, the chip temperature. (In the temperature range of interest using oC is more common.) TJoC or K change of junction temperature (see JESD51-50). For temperature differences oC is commonly used. VFV junction
39、 forward voltage IFA junction forward current PHW heat dissipated at the junction of the LED(see JESD51-50), also denoted as PHand referred to as heating power in JESD51-51. PoptW emitted optical power of the LED referred to as total radiant flux and denoted as ein CIE S 017/E, 2011 ILV. It is also
40、called total radiant power. PelW electrical power supplied to the LED which is equal to the product of the forward voltage and the forward current: Pel= VF IF. This quantity is denoted as P in CIE 127:2007. eW emitted optical power of the LED, alternate notation to Poptas defined and referred to in
41、CIE S 017/E, 2011 ILVas total radiant flux or radiant power. Vlm total luminous flux nm wavelength of the emitted light S() W/nm spectral power distribution indicating the radiant power of the emitted light at a given wavelength. e, WPE % radiant efficiency or energy conversion efficiency or wall pl
42、ug efficiency of the LED: 100 the value of the Poptemitted optical power divided by the Pelsupplied electrical power. Throughout this document WPE is defined for a single LED device. Vlm/W efficacy, the LEDs total luminous flux Vdivided by the Pelsupplied electrical power. ZJX, ZthJXK/W junction-to-
43、specific environment thermal impedance, the temporal change of junction temperature with respect to temperature of environment X, normalized to 1W heating power and scaled in z logarithmic time. IMmA value of the forward current of the LED applied as measuring current. IHmA value of the forward curr
44、ent of the LED applied as heating current. JEDEC Standard No. 51-52 Page 3 3 Terms, Definitions, and notations (contd) The everyday term (high) power LED is somewhat ambiguous, since there is a tendency to package multiple single pn-junction LED chips into a single package (sharing the same cooling
45、assembly and optics) or have multiple elementary pn-junctions on a single chip form an LED device. Also, in many cases, multiple packaged LEDs are assembled to a substrate (usually a high thermal conductivity board such as a metal core PCB or MCPCB in short) to form one single device. In this docume
46、nt, the phrase “LED” means a device used as a single light source with a generic anode and cathode electrical contact. All measured characteristics (e.g., thermal resistance, temperature sensitivity of the overall forward voltage, radiant flux, luminous flux, color, etc.) of array type single light
47、source LED devices are ensemble characteristics of the array. In such cases the array is considered a single chip equivalent device which possesses the measured ensemble characteristics of the array device. In the subsequent sections under term LED (or power LED) or LED device, it is meant either as
48、 an individually available single LED of any LED array arrangement or an equivalent LED of an LED array where elements of the array are not accessible individually, (this equivalent LED being characterized by its ensemble characteristics). Either configuration would have an exposed cooling surface w
49、hich is to be heat-sunk during normal operation. Regarding the term LED see also definition 6.8.5.1 of LED packages and definition 6.8.5.2 of the LED arrays in ANSI/IESNA RP 16-05 Addendum A. The scope of this document does not include any other solid-state lighting device defined in ANSI/IESNA RP 16-05 Addendum A. 4 Recommended test environment for LEDs As a reference environment for thermal and light output measurement of LEDs, temperature controlled cold-plates are recommended. Su
