The LT3791 is the latest in Linear Technology’s growing family of high power, high performance LED drivers designed to simplify power delivery to high brightness LEDs. The 4-switch buck-boost controller topology operates from input voltages above, below or equal to the output voltage while delivering constant currents from 1A up to tens of amps. The LT3791 also provides ±4% LED current accuracy and ±1.5% output voltage accuracy to ensure the highest performance LED solutions.
- 4-Switch Single Inductor Architecture Allows VIN Above, Below or Equal to VOUT
- Wide VIN Range: 4.7V to 60V
- Wide VOUT Range: 0V to 60V (55V LED)
- ±2% Output Voltage Accuracy
- Synchronous Switching: Up to 98.5% Efficiency
- ±6% LED Current Accuracy: 0V ≤ VOUT < 60V
LT3791 – 60V 4-Switch Synchronous Buck-Boost LED Driver Controller - [Link]
Simple and interesting circuit to fade LEDs. Watch effect on the link. It’s cool.
LED Fade – Pulsing Effect - [Link]
This is the successor to my old (and lame) RGB LED Ring project. Now you get 6-bit color depth (per color!) and a lot more bang.
Version ’2.0 alpha’ – an intermediate step to true enlightenment – uses one LED driver IC and 3 P-channel MOSFETs cycling through the primary colors. This requires special attention in the code to attempt color balancing (forced dot correction at all times).
As of ’2.0 beta’ (likely to become the final version) it comes with 3 dedicated constant current LED driver chips (MBI5168), which completely avoids multiplexing the LEDs and boosts brightness again. Color balancing is done entirely in hardware using 3 potentiometers. The hardware differences should be taken care of in the core part of the demo code, ‘User-land’ code is mostly the same.
RGB LED Ring V2 - [Link]
The ATTiny Candle is an LED candle. It uses a high brightness LED and some software to mimic the look of a traditional candle without the dangers associated with an open flame. I imagine they could be useful as movie props where you cannot afford to have a candle go out during a take or in your home in places not suitable for traditional candles such as in a wall niche or alcove.
ATTiny Candle - [Link]
This reference design from Maxim is a current controlled boost driver designed for long strings of LEDs. Driving many LEDs in series has advantages over driving them in parallel. In a parallel configuration each LED will need it’s own current limiting resistor or current control, while the series LEDs make use of a single current controlled power supply. The driver must support the combined voltage of all the LEDs in the string. The reference design can supply up to 100 volts, which translates to around 30 LEDs.
App note: Current controlled boost driver for long LED strings - [Link]
LEDs don’t dim well using a an adjustable resistor, instead a pulse-width modulator is usually used to blink them rapidly giving the appearance of less light. Giovanni brings the analog charm back to LED dimming by controlling brightness via an adjustment knob (machine translation). This dimmer reads the value of an adjustable trimmer resistor with an analog to digital converter, and adjusts a the PWM output accordingly.
LED dimmer using an analog knob - [Link]
Ultra-efficient LED puts out more power than is pumped in (Wired UK) – [via]
MIT physicists have managed to build a light-emitting diode that has an electrical efficiency of more than 100 percent. You may ask, “Wouldn’t that mean it breaks the first law of thermodynamics?” The answer, happily, is no.
The LED produces 69 picowatts of light using 30 picowatts of power, giving it an efficiency of 230 percent. That means it operates above “unity efficiency” — putting it into a category normally occupied by perpetual motion machines.
Ultra-efficient LED puts out more power than is pumped in - [Link]
Giorgos Lazaridis writes:
I decided to write this quick tutorial for two reasons: First because there are many people who would like to know more about driving and controlling LED lights, and second because i was provided an excellent LED driver chip from Farnell for test, and i wanted to put it under the microscope. So i will place this chip against some other LED drivers to see how good it is.
The chip that I’m talking about is the A6210 from Allegro Microsystems. It is a Buck-Regulating LED Driver able to drive up to 3A load with constant current, with switching frequencies up to 2 MHz and supply voltage from 9 to 46 volts. It has an optional PWM input to control the brightness of the LED. The sense voltage is down to 0.18 volts for higher efficiency.
LED driving and controlling methods - [Link]
Using constant current to drive LEDs is a good practice, but turning them on instantly can be dangerous for both the LED and the LED driver. Harmful spikes are generated when large currents are instantaneously turned on. This app note from Maxim describes how to soft start LEDs to increase overall lifetime and performance. [via]
An incandescent bulb requires some time to reach full brightness after you switch it on, and that delay gives the eye a comfortable interval for adjusting to the bright light. LED-based lights lack this property. Instead, their brightness goes from zero to 100% almost instantly. That property is welcome in a camera flash, but rather annoying for general lighting.
App note: Soft-Start in LED lighting - [Link]
High luminous intensity and a low height of Kingbright LED KA-3529 series will enable you to use them for displays backlighting and production of various indication panels.
Nowadays, for a backlight of displays or various panels, there are very often used white LEDs. However there are still a lot of reasons why to use a color backlight. In many applications a color backlight can increase contrast ratio or visibility of a display in a given environment, or it is simply more aesthetic.
Advantages / Features:
- high luminous flux 4.2-22 lm/ 150mA, according to a type
- small, only 1.3 mm high PLCC2 package
- low power consumption
- 120° large radiation angle
LEDs Kingbright KA-3529 with a high luminous intensity, maximum current up to 150 mA and small dimensions are very suitable for these purposes. In only 1.3mm high PLCC2 SMT package they require only a minimum of space. KA-3529 are available in blue, green, orange and red version.
LED in a PLCC package not only for a display backlight - [Link]