The new iW3606 and iW3608 single-stage, solid state lighting (SSL) LED drivers from iWatt feature a wide, flicker-free dimming range from 100% all the way down to 1% of measured light, to closely match the dimming performance of incandescent bulbs. This enables the smooth, “natural” dimming, with no light drop-out at the low end of the dimming range and virtually no dead travel where the light turns off before the dimmer control reaches the bottom of its travel. The very low internal power consumption of the iW3606 and iW3608 allows them to start at a very low dimming level of <5% of light output. This virtually eliminates pop-on, a phenomenon where the light does not turn on at low dimmer levels and as the dimmer level is raised, the light suddenly turns on. This also helps eliminate popcorning effects, in which various bulbs in multiple-light installations on the same dimmer circuit can turn on at different dimmer setting thresholds. [via]
New LED Drivers Deliver Exceptional Bulb Dimming Performance - [Link]
A versatile kit that can be configured to drive either constant voltage LED arrays or constant current LEDs. Use the kit to dim under-cabinet LED lighting using flexible LED strips or build your own LED desk lamp using High Brightness LEDs.
The majority of the circuit is identical for both types of LEDs. Two inexpensive NPN transistors and a few resistors are added to the circuit for constant current LEDs. It uses the ability of a MOSFET transistor to act either as a digital switch or linear current regulator.
Constant voltage LED arrays include built-in current limiting resistors. Typically these arrays come in a flexible tape form (such as Jameco part number 2128631) but may also be constructed from discrete LEDs and appropriate current limiting resistors (for example a string of 3 white LEDs wired in series with a 120 ohm resistor designed to operate at 20 mA with a 12 VDC power supply). When configured to drive constant voltage LED arrays, the dimmer circuit acts as a digital switch that turns on and off hundreds or thousands of times per second to modulate the LED brightness.
Universal CC/CV LED Dimmer - [Link]
Raj from Embedded Lab posted a new PIC project which is about building a mono color LED matrix marquee that consists of 320 LEDs in total that are arranged in 8 rows and 40 columns. The project uses PIC16F1847 microcontroller which receives the display data from a PC through a serial interface, and display it on the LED matrix scrolling from right to left.
LED Matrix Scrolling Marquee using PIC MCU and Shift Registers - [Link]
Here’s an interesting project by Steve of Tangent Audio the AZIZ project, a microcontroller-based LED microscope illuminator:
AZIZ is an LED microscope illuminator that I designed and built from scratch. It is designed around a Texas Instruments TLC59116 constant-current PWM LED driver chip, and an Atmel ATTiny1634 8-bit microcontroller.
AZIZ: DIY LED microscope illuminator - [Link]
Drawing only microamps (other than load current), this circuit switches in accordance with ambient light levels. Raju Baddi writes:
You can use an LED as a photoelectric sensor. A previous Design Idea shows that such a switch is highly power-efficient, consuming almost no power (Reference 1). However, you cannot adjust that configuration to switch at the desired light intensity. You can adjust the circuit in this Design Idea to any threshold level of light intensity necessary to maintain the on state of the photoelectric switch while retaining almost the same power efficiency of the original circuit
Adjust power-efficient LED switch to any light intensity – [Link]
We enlarged our stock offer of well-proven LEDs in a PLCC-2 package with new improved types.
KA-3528 series of SMT diodes is not a novelty and many of you may know it already for several years, however this series is being continuously enriched with new types. Kingbright as a reliable producer of LEDs always improves their specification, that´s why we also counterchange our offer with new types which overcome their predecessors. It ensures a long-term availability of LEDs in this package and at the same time it ensures still lower power supply demands thanks to a higher luminous intensity of new types.
KA-3528 are universal colour SMT LEDs in a PLCC-2 package, with higher luminous intensity and 20mA nominal current, suitable for backlighting of push-buttons, panels etc. KA-3528 also offers a possibility to choose from several colors (wave lengths) even within one color group.
The PLCC-2 package has good optical properties (reflector) and good thermal properties at the same time, what gives a supposal of a long lifetime. In the recent period we enriched our offer with for example these types – KA-3528LSGS, KA-3528QBCT-G a KA-3528VGS-A.
Detailed information will provide you the datasheets at particular types as well as overview of Kingbright SMT diodes. In case of interest in any Kingbright component, please contact us at email@example.com.
Universal SMT LEDs series KA-3528 will attract attention – [Link]
Researchers at the University of Illinois at Urbana-Champaign and Washington University in St. Louis developed ultrathin, flexible optoelectronic devices – including LEDs the size of individual neurons – that are lighting the way for neuroscientists in the field of optogenetics and beyond.
Optogenetics is the process by which genetically-programmed neurons or other cells can be activated by subjecting them to light. Among other things, the technology helps scientists understand how the brain works, which could in turn lead to new treatments for brain disorders. Presently, fiber optic cables must be wired into the brains of test animals in order to deliver light to the desired regions. That may be about to change, however, as scientists have created tiny LEDs that can be injected into the brain. [via]
Tiny Injectable LEDs Help Neuroscientists Study the Brain - [Link]
Plessey has released samples of their new gallium nitride (GaN) on silicon LEDs. These entry level products, fabricated on 6-inch wafers, are the first LEDs manufactured using GaN on silicon technology to be commercially available anywhere in the world.
Manufactured using Plessy’s proprietary large diameter GaN on silicon process technology, the LEDs are fabricated on a 6-inch line at Plessy’s facility in Plymouth, England. According to Plessey, the combination of standard semiconductor manufacturing processing and the 6-inch fab line provides yields of greater than 95% and fast turnaround , creating significant cost advantage over sapphire and silicon carbide based solutions for LEDs of similar quality. [via]
First GaN on Silicon LEDs Now Available - [Link]
Richard Comerford writes:
The solid-state lighting (SSL) surge has created a concomitant boom market for electronics to drive LEDs in various different applications, ranging from incandescent-replacement light bulbs to architectural lighting to streetlights and more. These new driver ICs and modules do more than simply provide power in the form needed by LEDs. Some devices can perform additional functions that engineers want in designing full-featured lighting system, such as dimming control and thermal regulation. In this article, we will examine some of the latest driver ICs and modules for LEDs, and the choices they offer the designer.
The Latest LED driving ICs and Modules - [Link]
Here is a great application note from Maxim describing the process of designing a high voltage LED driver. The guide goes step by step so it’s easy to follow it.
This application note details a step-by-step design process for the MAX16833 high-voltage high-brightness LED driver. This process can speed up prototyping and increase the chance for first-pass success. A typical design scenario is presented, along with example calculations based on the design constraints. Component selection trade-offs are discussed. A spreadsheet calculator is included to help calculate external component values. This application note focuses on the boost converter topology. However, the same process can be applied to other topologies as long as the underlying equations are understood.
Step-by-Step Design Process for the MAX16833 High-Voltage High-Brightness LED Driver - [Link]