LED drivers are electrical devices that regulate the power of LEDs. What makes them different from conventional power supplies is their ability to respond to the ever-changing need of LEDs in a circuit by supplying a constant amount of power as electrical properties change with temperature.
The PCA9622 is an I2C-bus controlled 16-bit LED driver optimized for voltage switch dimming and blinking 100 mA Red/Green/Blue/Amber (RGBA) LEDs. Each LED output has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at 97 kHz with a duty cycle that is adjustable from 0 % to 99.6 % to allow the LED to be set to a specific brightness value. An additional 8-bit resolution (256 steps) group PWM controller has a fixed frequency of 190 Hz and an adjustable frequency between 24 Hz to once every 10.73 seconds with a duty cycle that is adjustable from 0 % to 99.6 % that is used to either dim or blink all LEDs with the same value.
These LED drivers are based on system-centric, mixed-signal LED driver technology for backlighting and solid-state lighting (SSL) applications. This broad-based and rapidly growing market includes LCD TVs, PC monitors, specialty panels (industrial, military, medical, avionics, etc.) and general illumination for the commercial, residential, industrial and government market segments. LED drivers utilize a proprietary and patented combination of analog and digital circuit techniques and power control schemes.
- PCA9622 I2C-bus controlled 16-bit LED driver
- 2C-BUS/SMBus MASTER
- Resistor 10kΩ ( 27 units)
- LED (88 units)
- Voltage Source 40Vdc
- Voltage Source 5Vdc
I2C Bus Controlled LED Drivers for backlighting and SSL applications – [Link]
by Hua (Walker) Bai:
The meaning of the term “high power LED” is rapidly evolving. Although a 350mA LED could easily earn the stamp of “high power” a few years ago, it could not hold a candle to the 20A LEDs or the 40A laser diodes of today. High power LEDs are now used in DLP projectors, surgical equipment, stage lighting, automotive lighting, and other applications traditionally served by high intensity bulbs. To meet the light output requirements of these applications, high power LEDs are often used in series. The problem is that several series-connected LEDs require a high voltage LED driver circuit. LED driver design is further complicated by applications that require fast LED current response to PWM dimming signals.
Design Notes: 60V, Synchronous Step-Down High Current LED Driver - [Link]
There is a new 8mm RGB LED introduced to the WS2812 family of LEDs. cpldcpu writes:
There is a new addition to the popular WS2812 family of RGB LEDs with integrated controller: A 8mm through hole version. Right now they seem to be in pilot production stage. The only place that has them is Soldering Sunday where they are called PixelBits. My understanding is that they will also be available at the usual sources later this year. I got a couple of them to test for compatibility with my light_ws2812 library.
New member of the WS2812 RGB LED family - [Link]
This project is a simple LED tester and LED polarity checker. It can be used to check 1206, 0805, 0603 and 5mm LEDs. All parts are readily available and they are very cheap. Usage is very simple. Just press the tack switch to first check the battery is good. The blue led will turn on. Now you are ready to test your leds and check their polarity.
Simple SMD LED tester - [Link]
“Click And See “ is a system supporting the search of electronic components. The idea came during yesterday’s shopping in one of the electronics stores , cabinets with electronic components fill the entire wall. When buying several different components , the seller needs time to find them first in your computer , then in the appropriate bins , and the queue of customers getting longer … To facilitate this, I designed a simple , wireless and easy to expand the system to highlight the drawer of the element that want to buy .
more info here: CLICK_AND_SEE_ENG
Click and See – find electronics parts with a click - [Link]
James Wood designed a simple circuit that is able to indicate when the battery of a system is low and needs replacement. He writes:
The Design Idea in Figure 1 indicates a low-battery condition in an audio test instrument that is powered by four AA cells. As the instrument was otherwise an all-discrete design, this same approach seemed more in keeping with the spirit of the project than the use of a single-sourced integrated circuit.
A garden-variety red LED serves as both the indicator and the voltage reference. A small current through R5 forward biases the LED, but its glow at this low value is barely visible, even in a dark room.
Simple circuit indicates a low battery - [Link]
This is a heart-shaped LED chaser would be a nice gift for Valentine’s Day. Circuit is very simple and uses the 555 timer IC (configured as astable multivibrator) and CD4017B decade counter.
The object of your desire will not be able to resist a heart-shaped LED chaser, lovingly hand-crafted on perfboard with a CD4017B decade counter and 555 astable. But you probably can’t go wrong with flowers and chocolates as well. Just to be on the safe side.
Heart-shaped LED chaser for Valentine’s Day - [Link]
Greeeg at the 430h forum has been working on a RGB LED ring clock:
The clock is comprised of 2 rings of 60 LEDs each. the LEDs are WS2812 parts, which include a built-in driver. The PCB is one of the interesting parts of this clock. I designed the board in altium as a single 6 LED segment. and then left pads at each end to allow them to be soldered onto another segment. Currently I am using a MSP-EXP430FR5739 board to drive it, using some very in-efficient assembly code that requires a 20MHz clock.
RGB LED ring clock - [Link]
Nick Leijenhorst build a 555 PWM circuit to dim his room LED lighting. He writes:
I wanted to dim my room LED lighting with a potentiometer, and decided on creating a solution from scratch to make it more fun and educative. I decided to go with the fairly well-known 555 PWM circuit. To decrease size and for learning purposes I decided on using surface-mount components for the first time. The reason I wanted to make this 555 PWM circuit is actually just to see if I could solder SMD components on home-etched PCB’s, and to see how hard it actually is.
Surface-mount 555 PWM circuit - [Link]