scope:

This Technical Report describes methods for the measurement of optical properties of LED modules (with or without integrated control gear) and LED light engines that are connected to DC or AC power supplies. The report includes both continuous operation and also modulated operation where the modulation is fast enough to give the appearance of steady emission. It covers, for example, devices intended for use in lamps and luminaires, signals, signs, backlights and static displays. Both planar and non-planar sources are included. Measurement methods specific to dynamic displays containing video information, flashing lights and devices operated in asynchronous mode are not within the scope of this report.

In particular, this Technical Report deals with all LED products that comprise multiple dice or packages, and/or LED products of which the forward voltage, U_F, of a single LED is not accessible, or does not characterize an average junction temperature, T_J, in case of multiple dice.

This document does not cover single-diode LED packages and single-die, multiple-junction LED packages. Appropriate methods for the measurement of these products are described in the CIE publications 225 (CIE 2017a) using the DC method and 226 (CIE 2017b) using the pulse method. Measurements of LED luminaires and LED lamps are also not covered in this document; such measurements are described in CIE S 025 (CIE 2015a).

LED modules and LED light engines containing chip-on-board (COB) LED arrays, where multiple LED dice or surface-mounted device (SMD) LEDs are packaged onto a single metal core printed-circuit board (PCB) or ceramic board, can be measured according to this Technical Report if there is an on-board thermistor or a temperature reference point is specified for measuring the test-point temperature, T_p. Such products can also be measured using the methods described in CIE publications 225 (CIE 2017a) and 226 (CIE 2017b) provided that a single forward voltage, U_F, characterizes an average junction temperature, T_J, of all junctions.