Jianwen Shao EDN Due to their light output and long life, high-brightness LEDs are well-suited for use in flashlights. Typically, the LEDs are driven with a constant current. So when the battery voltage drops, the flashlight just stops working. In ...
There is much interest in LED-based lighting due to the availability of high-power, high-efficiency white and other-color LEDs (Reference 1). Because an LED is a current-controlled device, typical control circuits regulate the current through the ...
LED applications are booming: backlighting for LCD TVs, projectors, and computer displays, camera flashes, and vehicle brake lights and taillights are just a few. All require constant-current LED drivers that offer a high dimming ratio, high ...
A common method for driving multiple power LEDs is through two parallel strings. This inexpensive and less critical driver circuit can provide a lower voltage. However, the driver circuit must deliver twice the current of other methods and needs a ...
This Design Idea circuit regulates the current through one or more LEDs, making it almost independent of supply voltage. Its main advantage is a very small dropout voltage, which can be less than 100 mV. The design could find use on LED strips, ...
The circuit in Figure 1 represents a simple and inexpensive way to provide additional bicycling safety. A conventional bicycle-generator lighting system works with the circuit to provide safety lighting for several minutes after the bicycle has ...
Keeping low-voltage outdoor lights illuminated takes some effort. Bulbs burn out, and connections corrode. HB LEDs (high-brightness light-emitting diodes) seem like acceptable replacements, but most are available only in surface-mount packages, ...
High-power LEDs challenge electronics engineers to design accurate and efficient, yet simple, driver circuits. Conventionally, driving high-power strings with accurate current requires dedicated switching regulators. Choosing a discrete driver ...
Tom Gay EDN Most current microcontrollers offer I/O ports that can change their functions during program execution. As outputs, the circuits can sink and source reasonably large amounts of current. This Design Idea shows three alternative methods ...
I needed a simple LED indicator showing that a particular voltage level had been reached specifically, that a capacitor had charged to a particular potential. I was convinced that there must be a way that a programmable zener diode, such as the ...