Pulsed LED application like flash LEDs requires adequate thermal management to counter the heavy heat caused by larger current, here’s an app note from OSRAM discussing on thermal management of LEDs. Link here (PDF)
This application note focuses on how to develop an adequate thermal management for LEDs in camera flash applications. It provides information on critical factors and the thermal properties of LEDs during a range of operation modes as well as information on how to develop an adequate thermal management in flashlight applications.
App note from OSRAM on InGaN LEDs dimming method without penalty on its wavelength. Link here (PDF)
While the InGaN technology produces the brightest light output across Blue, Deep blue, Verde, True green and White, it is important to understand that the wavelength of the light emitted depends on the forward current. In order to avoid shifts in the color, the dimming strategy must be considered carefully.
An App note from OSRAM on an Intelligent control circuitry example using a PIC Microcontroller. Link here (PDF)
Nowadays, applications increasingly make use of LEDs as a replacement for traditional light bulbs. For example, LEDs are frequently used in the design of automobile tail lights, signal lights, traffic signals, and variable message signs.
LEDs provide several advantages over traditional light bulbs, such as smaller size and longer life. In many applications, the LEDs must be driven with intelligent control circuitry. According to the task at hand, this control circuitry must be able to fulfill various functions and tasks.
App note from OSRAM on thermal resistance for LEDs and IREDs (IR emitting diodes). Link here (PDF)
In order to achieve the expected reliability, lifetime and optimal performance of LEDs, especially for high-power LEDs, appropriate thermal management is of the utmost importance. One of the key parameters for good thermal management is the temperature of the active semiconductor layer designated as the junction temperature. The manufacturer’s recommended maximum junction temperature should therefore not be exceeded during operation, in order to prevent damage to the component. Ideally, the junction temperature should be kept as low as possible for the given application.
Due to the design principle of the LEDs, the junction temperature of the LED can not be measured directly.
App note from OSRAM on their ALS device SFH5701, its operation and application method. Link here (PDF)
The SFH5701 is a small, two-wire, linear output current ambient light sensor (ALS) with current amplifier and dark current compensation. The ALS is capable of resolving a wide range of ambient light levels (10 mlx – 10 klx) tailored to the spectral response of the human eye and operational from -40 °C to 100 °C.
Light guide basics app note from OSRAM. Link here (PDF)
Light Guides are used wherever the light of a light source should be distributed homogeneously over a particular area, when there is a spatial distance between light source and the area which is to be illuminated.
App note from OSRAM about different approaches on LED string diagnostic in automotive. Link here (PDF)
One requirement especially in automotive applications is the diagnosis of failures in functions and systems. Therefore light functions realized with LEDs like break light, daytime running light, low and high beam may require a diagnostics function. This application note describes some items which have to be taken into account, when a diagnostic function for a LED string or a multi LED module has to be realized.
Chemical compatibility of LEDs application note from OSRAM. Link here (PDF)
The performance and stability of light emitting diodes (LEDs) may be influenced by various chemical incompatibilities arising from chemicals and materials used, amongst other things, in luminaire construction, or by gases in the proximate environment of LEDs during field operation. Nevertheless, LEDs have to fulfill a wide range of customer needs and requirements in indoor and outdoor applications.
This application note provides information about the chemical compatibility of certain substances with LEDs, particularly with regard to some of their basic components. In this context, the main mechanisms of chemical incompatibility are illustrated using examples of blue and white LEDs.
Brief app note from OSRAM, LEDs for heart rate monitoring through skin reflection of emitted light. Link here (PDF)
This application note provides a short introduction into the general use of LEDs for wearable applications, with a focus on heart rate monitoring.
App note from OSRAM about LED rework on signages and their demand for more sophosticated tools. Link here (PDF)
SMT LEDs have became more and more popular in video wall and signage applications, replacing radial LEDs. This leads to more difficulties during the repair or replacement of failed LEDs on PCBs, especially for QFN (Quad Flat No-lead) packages, as there is no exposed lead. This application note provides basic information on how to rework the SMT LEDs in video wall and signage applications. To describe the rework process the DISPLIX Oval LED was chosen an example, as the rework of this LED is more challenging due to the lack of exposed lead and the oval lens on top. However, the procedure is also suitable for other LEDs. In this application note details on the materials used, examples of suitable equipment and the process are presented and described. Finally, the test results of the LED after the rework process are presented, showing that in this case the rework procedure did not cause any damage to the LED itself.