App note: Thermal consideration of flash LEDs

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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: Dimming InGaN LEDs

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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.

App note: Driving LEDs with a PIC Microcontroller

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: Package-related thermal resistance of LEDs

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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.

RTC based automatic LED lamp

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Dilshan Jayakody published a new build:

This is real-time clock based automatic LED lamp which we originally designed to use as night light. This lamp can programmed to turn on and off at the specific time of the day. For example, it can program to turn on at 6 PM on each day and to turn off at 4 AM next day.
The core component of this project is PIC16F883 MCU and it’s firmware is developed using MikroC Pro for PIC. We select this MCU because of it’s 7 KB flash memory, I2C, UART, E2PROM and built-in 8-bit and 16-bit timers.

See the full post on his blog.

Minimalistic 1D pong

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Here’s a minimalistic 1D Pong game from Vagrearg:

How little do you need for a game
An exercise in futility. That is what many would call this endeavor. How few elements (signifiers and affordances) do you need to not only recognize a game for what it is, but also are able to play it?
It turns out that you only need very little to do very much.

Project info at vagrearg.org.

App note: Pulsed Over-Current Driving of LEDs

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App note from CREE on driving LEDs over its specified current capability. Link here (PDF)

The Applications Engineering team at Cree is often asked whether it is safe to operate Cree XLamp® LEDs with pulsed currents above the maximum data-sheet rating. This question is usually asked in the context of legitimate product requirements such as those posed by emergency-vehicle applications, specialized stroboscopic illumination and even pulsed modulation for general-illumination dimming applications.

The short answer is “it depends.” Multiple variables affect both initial and long-term performance and reliability of an LED. These include thermal resistance, pulse duration, as well as current amplitude, frequency and duty cycle.

App note: Avoidance of ceramic-substrate-based LED chip cracking induced by PCB bending or flexing

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Application note from CREE on the causes of ceramic-substrate-based failures due to PCB board stresses and how to minimize their occurrence. Link here (PDF)

Printed circuit board (PCB) bending and/or flexing is an unavoidable phenomenon that is known to exist and is easily encountered during electronic board assembly processes. PCB bending and/or flexing is the fundamental source of tensile stress induced on the electronic components on the board assembly. For more brittle components, like ceramic-based electronic components, micro-cracks can be induced, which can eventually lead to a fatal failure of the components. For this reason, many standards organizations throughout the world specify the methods under which electronic board assemblies must be tested to ensure their robustness, sometimes as a precondition to more rigorous environmental tests such as thermal cycling or thermal shock.

App note: Preventing LED failures caused by corrosive material

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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.