New Power Factor-Corrected AC-DC Drivers for LED Lighting Apps

ON Semiconductor has announced two new series of power factor corrected (PFC) offline AC-DC drivers for high performance LED lighting applications. Extending the NCL3008x family of products, the NCL30085, NCL30086, and NCL30088 address single-stage design implementations up to 60 W that require high power factor. The NCL30030 broadens the existing solutions which support higher power (up to 150 W) two-stage topologies that require low optical ripple and wide LED forward voltage variation.

 

Source: ON Semiconductor

Source: ON Semiconductor

The NCL30085, NCL30086, and NCL30088 use a PFC current control algorithm that makes them suitable for flyback buck-boost and SEPIC topologies. By operating in quasi-resonant mode, they can deliver optimum efficiency across wide line and load levels. The innovative control methodology enables strict current regulation to be achieved (within 2% typically) solely from the primary side.

 

The non-dimmable NCL30088 is complemented by the “smart-dimmable” NCL30086, supporting analog and pulse-width modulation (PWM) dimming with a single input that controls the average LED current. Completing the series is the NCL30085, which supports three levels of log step dimming: 70%, 25%, and 5%. As a result, it permits light output reduction by toggling the AC switch on/off to signal the controller to lower the LED current point. All three devices feature user-configurable current thermal fold-back mechanisms that help prevent overheating and enable manufacturers to support longer lifetime warranties.

 

The NCL30085 and NCL30088 are available in SOIC-8 packages. The NCL30086 is offered in an SOIC-10 package with pricing of the series starting at $0.35 per unit in 10,000-piece quantities.

 

The NCL30030 is a two-stage PFC controller plus quasi-resonant flyback controller optimized for medium and high power LED lighting applications up to 150 W. This device is best suited for commercial lighting such as lowbay, highbay, and streetlighting. The NCL30030 makes use of a proprietary multiplier architecture to achieve low harmonic distortion and near-unity power factor while operating in critical conduction mode (CrM).

The NCL30030 is in an SOIC−16 package with one pin removed for high-voltage spacing. Pricing starts at $0.65 per unit in 10,000-piece quantities.

 

Source: ON Semiconductor

LED Light Engines Deliver Up to 4,000 Lumens

Innovations in Optics has announced  high-power white LED light engines for OEM fiberoptic illumination. LumiBright Light Engines couple directly to liquid light guides and fiber bundles with no additional optics. They deliver up to 4,000 lumens into the light guide.

The 2400-W (Source:

The 2400-W (Source: Innovations in Optics)

Offering substantial cost and operational advantages, white LEDs are becoming popular light guide illumination sources for many technical applications that were historically dominated by tungsten halogen and HID lamps. LumiBright light engines feature patented technologies that encompass non-imaging optics with chip-on-board (COB) LED arrays on metal core circuit boards to provide both optimum luminous efficacy and ideal thermal management. Unlike the so called “big chip” LEDs used in many light guide illuminators, LumiBright light engines feature large source size and emit into a numerical aperture that matches the acceptance cone angle and diameter of light guide systems. The unique design results in many more lumens emitted from light guides relative to the big chip Lambertian emitters.

The LumiBright 2400B-400-W has a 0.66 numerical aperture (NA) and illuminates fiber bundles and light guides sized from 6.0 to 8.0 mm in diameter. Well suited for applications in machine vision and remote source illumination, the light engine generates up to 4,000 lumens. The 2400B-500-W is ideally suited for endoscope and microscope illuminator applications with a 0.60 NA for light guides that are 3.0 to 5.0 mm in diameter. The 2400B-500-W produces up to 1,500 lumens. Available light engine system accessories include thermal management devices, wire harnesses, and driver/controllers.

Source: Innovations in Optics

Data Communication Between “Smart” Pendants

As head of the Computer Science and Software  Engineering department at Penn State Erie, The Behrend College, Chris Coulston is busy.

But not too busy to surf the ‘Net for design inspiration.

And one of his latest projects may earn him the title of “social jewelry designer,” along with college professor and department chair.

In the June issue of Circuit Cellar, Coulston writes about his design and construction of an RGB LED pendant that “cycles through a color sequence, detects when another pendant is brought into its proximity, and communicates color sequence information to the other pendant through its LED.” The heart of the design is a Seoul Semiconductor SFT722 RGB LED.

Coulston was online a few years ago when he ran across the first half of his project inspiration—a Mitsubishi Electric Research Laboratories technical report titled “Very Low-Cost Sensing and Communication Using Bi-directional LEDs.” The report, Coulston says, “describes how an ordinary LED with no additional circuitry can act as a full-duplex communication channel.”

Pendant’s two boards

His remaining inspiration came from an article he recalled appearing in Circuit Cellar a decade ago.

The Mitsubishi labs technical report “got me thinking about Jeff Bachiochi’s article ‘Designing with RGB LEDs’ (Circuit Cellar 159, 2003), in which the challenges associated with designing a piece of LED jewelry are described,” Coulston says. “The fusion of these two ideas was the inspiration for my social jewelry design.”

Coulston’s design includes a pair of circuit boards, the upper containing the LED and analog circuitry and the lower containing the microcontroller.

“The prototype pendant is mainly controlled through a USB-to-USART bridge,” Couston says. “Its power is supplied by the same connection.”

He invites anyone who is  “curious how an LED can be used as a transceiver and how it’s used to build a piece of social jewelry” to read his article. You’ll find it in next month’s issue of Circuit Cellar.

Q&A: Raspberry Pi Innovation

Orlando, FL-based web app developer and blogger Shea Silverman recently received Kickstarter funding for the latest version of PiPlay, his Raspberry Pi-based OS. Shea and I discussed his ongoing projects, his Raspberry Pi book, and what’s next for PiPlay.—Nan Price, Associate Editor

 

silverman

Shea Silverman

NAN: What is your current occupation?

SHEA: Web applications developer with the Center for Distributed Learning at the University of Central Florida (UCF).

NAN: Why and when did you decide to start your blog?

SHEA: I’ve been blogging on and off for years, but I could never keep to a schedule or really commit myself to writing. After I started working on side projects, I realized I needed a place to store tips and tricks I had figured out. I installed WordPress, posted some PhoneGap tips, and within a day got a comment from someone who had the same issue, and my tips helped them out. I have been blogging ever since. I make sure to post every Friday night.

NAN: Tell us about PiPlay, the Raspberry Pi OS. Why did you start the OS? What new developments, if any, are you working on?

piplay-case

Shea’s PiPlay Raspberry Pi OS recently reached 400% funding on Kickstarter.

SHEA: PiPlay is a gaming and emulation distribution for the Raspberry Pi single-board computer. It is built on top of the Raspbian OS, and tries to make it as easy as possible to play games on your Raspberry Pi. My blog got really popular after I started posting binaries and tutorials on how to compile different emulators to the Raspberry Pi, but I kept getting asked the same questions and saw users struggling with the same consistent issues.

I decided I would release a disk image with everything preconfigured and ready to be loaded onto an SD card. I’ve been adding new emulators, games, and tools to it ever since.

I just recently completed a Kickstarter that is funding the next release, which includes a much nicer front end, a web GUI, and a better controller configuration system.

NAN: You wrote Instant Raspberry Pi Gaming. Do you consider this book introductory or is it written for the more experienced engineer?

SHEA: Instant Raspberry Pi Gaming is written like a cookbook with recipes for doing various tasks. Some of them are very simple, and they build up to some more advanced recipes. One of the easier tasks is creating your user account on the Pi Store, while the more advanced recipes have you working with Python and using an API to interact with Minecraft.

Readers will learn how to setup a Raspberry Pi, install and use various emulators and games, a bit about the Minecraft API, and common troubleshooting tips.

pitroller

The Pitroller is a joystick and buttons hooked up to the GPIO pins of a Raspberry Pi, which can act as a controller or keyboard for various emulators.

NAN: You are a member of FamiLAB, an Orlando, FL-based community lab/hackerspace. What types of projects have you worked on at the lab?

miniarcade

Disney director Rich Moore poses with Shea’s miniature arcade machine. The machine was based on Fix It Felix Jr. from Disney’s Wreck It Ralph.

SHEA: I spend a lot of time at the lab using the laser cutter. Creating a 2-D vector in Inkscape, and then watching it be cut out on a piece of wood or acrylic is really inspiring. My favorite project was making a little arcade machine featuring Fix It Felix Jr. from Wreck It Ralph. A marketing person from Disney was able to get it into the hands of the director Rich Moore. He sent me a bunch of pictures of himself holding my little arcade machine next to the full size version.

NAN: Give us a little background information. How did you become interested in technology?

SHEA: My mom always likes to remind me that I’ve been using computers since I was 2. My parents were very interested in technology and encouraged my curiosity when it came to computers. I always liked to take something apart and see how it worked, and then try to put it back together. As the years went on, I’ve devoted more and more time to making technology a major part of my life.

NAN: Tell us about the first embedded system you designed.

SHEA: I have a lot of designs, but I don’t think I’ve ever finished one. I’ll be halfway into a project, learn about something new, then cannibalize what I was working on and repurpose it for my new idea. One of the first embedded projects I worked on was a paintball board made out of a PICAXE microcontroller. I never got it small enough to fit inside the paintball marker, but it was really cool to see everything in action. The best part was when I finally had that “ah-ha!” moment, and everything I was learning finally clicked.

NAN: What was the last electronics-design related product you purchased and what type of project did you use it with?

SHEA: At UCF, one of our teams utilizes a ticket system for dealing with requests. Our department does a hack day each semester, so my coworker and I decided to rig up a system that changes the color of the lights in the office depending on the urgency of requests in the box. We coded up an API and had a Raspberry Pi ping the API every few minutes for updates. We then hooked up two Arduinos to the Raspberry Pi and color-changing LED strips to the Arduinos. We set it up and it’s been working for the past year and a half, alerting the team with different colors when there is work to do.

NAN: Are you currently working on or planning any projects?

SHEA: My Kickstarter for PiPlay just finished at 400% funding. So right now I’m busy working on fulfilling the rewards, and writing the latest version of PiPlay.

NAN: What do you consider to be the “next big thing” in the industry?

SHEA: Wearable computing. Google Glass, the Pebble smart watch, Galaxy Gear—I think these are all great indicators of where our technology is heading. We currently have very powerful computers in our pockets with all kinds of sensors and gadgets built in, but very limited ways to physically interact with them (via the screen, or a keypad). If we can make the input devices modular, be it your watch, a heads-up display, or something else, I think that is going to spark a new revolution in user experiences.

Battery Charger Design (EE Tip #130)

It’s easy to design a good, inexpensive charger. There is no justification for selling cheap, inadequate contraptions. Many companies (e.g., Linear Technology, Maxim, Semtech, and Texas Instruments) supply inexpensive battery management ICs. With a few external parts, you can build a perfect charger for just about any battery.

Texas Instruments’s UC2906 is an older (Unitrode) IC designed to build an excellent sealed lead-acid battery charger with a sophisticated charging profile. Figure 1 shows the recommended charger circuit.

Figure 1: This lead-acid battery charger uses Texas Instruments’s UC2906 IC.

Figure 1: This lead-acid battery charger uses Texas Instruments’s UC2906 IC.

In addition to the IC, only a handful of resistors and a PNP power transistor Q1 are needed to build it. Q1 must be rated for the maximum charging current and fitted with a heatsink.

An LED with its current-limiting resistor R can be connected to pin 7, which is an open-collector NPN transistor, to indicate the presence of power. Similarly, an LED with a series resistor could be connected to pin 9, which is also an open-collector NPN transistor to indicate overcharge (it is not used in Figure 1). The UC2906 datasheet and the Application Note provide tables and equations for selection of resistors Rs, Rt, RA, RB, RC, and RD and suggestions for adding various features.

Editor’s Note: This is an excerpt from an article written by George Novacek, “Battery Basics (Part 3): Battery Management ICs,” Circuit Cellar 280, 2013.