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.
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.
White paper about matrix LED usage from Integrated Silicon Solution Inc. (ISSI). Link here (PDF)
People today come in contact with a wide range of consumer electronics (CE) devices in their daily lives. CE devices have become increasingly complex with added functionality enabled by MCU’s which provide the intelligence for automating functions. Control panels used in appliances and other equipment leverage MCUs and several integrated circuits to enable functions, such as sensing, process control and user interface (UI).
The user interface consists of input controls, visual and audio feedback used to configure the product to perform complex tasks. An aesthetically pleasing UI is a major differentiating feature for home appliances such as ovens, washing machines and refrigerators. Home appliance UIs commonly use capacitive or inductive touch sensing to provide an easy to clean interface unmatched by mechanical buttons. In addition to touch sensing, a UI has to provide audio and visual feedback in response to the user selection. The UI may not be the most important factor in determining the commercial success of CE devices. However, once parity is established on the major functions such as washing capacity, energy efficiency, etc, the UI becomes a key differentiator. Today, parity has been established on most of the important factors making the UI a product differentiating factor.
As the trend continues to move away from purely mechanical switches to a fully electronic interface expect to see demand for LEDs and drivers to continue increasing.
I got a request, to design and build an electronic metronome. You can find several on the market, but the problem it is ether producing voice or the classical mechanical metronome. The requirement here was a visual effect. To be precise four LEDs for 4/4 beat. It is required for drumming where you have no chance to hear the clicking (or maybe just through headphones).
The defacto ‘hello world’ for microcontrollers is blink a LED at a steady rate. This is exactly what I’m going to do today. I made a small 5×5 development board, soldered it up and started programming. In this first example we not gonna use fancy IRQs or timers to blink at a steady rate, but we insert NOPsas delay. This would give an idea of the RAW performance of the chip. The used code is simple; set up the maximum available clock available and then toggle RA0 for ever.
When debugging algorithms in an autonomous vehicle a light that can show algorithm state in real time was proven to be effective for easier debugging and additional insight to what is going on in the code.
Because all existing signal light were either to bulky or too expensive we decided to build our own. It was actually quite simple with few key elements:
In my post Driving a SparkFun 48-Segment RGB LED Bar Graph, I stated that the hardware built there could be used to drive the LED bar graph with any combination of hardware and software that could drive one of the common 32×32 or 32×16 RGB LED matrices. Today I’m back to prove that point. In this post, I ditch the FPGA and drive the 48-segment RGB LED bar graph using a Teensy 3.2 board and the Pixelmatix SmartMatrix 3 library.
Another white paper from Lumileds about LED thermal resistance. Link here (PDF)
Thermal performance is the most critical factor of a well-designed LED lighting system. A lighting system with proper thermal design has higher efficacy, meaning more light can be extracted using less energy, and better long term reliability.