In electronics, an LED circuit or LED driver is an electrical circuit used to power a mild-emitting diode (LED). The circuit must present sufficient current to light the LED at the required brightness, energy-efficient bulbs however should limit the current to prevent damaging the LED. The voltage drop across a lit LED is approximately constant over a variety of working current; subsequently, energy-efficient bulbs a small increase in applied voltage drastically increases the present. Quite simple circuits are used for low-energy indicator LEDs. More complex, current supply circuits are required when driving high-power LEDs for illumination to achieve right present regulation. The simplest circuit to drive an LED is through a series resistor. It is often used for indicators and digital shows in many shopper appliances. Nevertheless, this circuit isn't power-efficient, because power is dissipated in the resistor as heat. With a sufficiently high supply voltage, a number of LEDs in sequence will be powered with one resistor.

The voltage versus present characteristics of an LED is just like any diode. Current is approximately an exponential function of voltage in line with the Shockley diode equation, and a small voltage change might end in a big change in current. If the voltage is under or equal to the threshold no current flows and the result's an unlit LED. If the voltage is just too high, energy-efficient bulbs the present will exceed the maximum ranking, overheating and EcoLight probably destroying the LED. LED drivers are designed to handle fluctuation load, providing enough current to realize the required brightness while not allowing damaging levels of present to move. Drivers may be constant present (CC) or constant voltage (CV). In CC drivers, the voltage modifications while the present stays the identical. CC drivers are used when the electrical load of the LED circuit is either unknown or fluctuates, for EcoLight dimmable instance, a lighting circuit the place a variable variety of LED lamp fixtures could also be installed. This will encourage the present to increase.

An active fixed current supply is commonly used for high energy LEDs, stabilizing gentle output over a variety of input voltages which could improve the useful life of batteries. Lively fixed present is often regulated using a depletion-mode MOSFET (metal-oxide-semiconductor subject-impact transistor), which is the best present limiter. Low drop-out (LDO) fixed present regulators also permit the entire LED voltage to be a better fraction of the power supply voltage. Switched-mode power provides (e.g. buck, boost, and buck-boost converters) are used in LED flashlights and family LED lamps. Power MOSFETs are usually used for switching LED drivers, which is an environment friendly solution to drive high-brightness LEDs. Power integrated circuit (IC) chips are broadly used to drive the MOSFETs straight, EcoLight without the need for added circuitry. Series resistors are a easy approach to stabilize the LED current, however energy is wasted within the resistor. Miniature indicator LEDs are usually driven from low voltage DC by way of a present-limiting resistor.

Currents of 2 mA, EcoLight home lighting 10 mA and 20 mA are widespread. Sub-mA indicators could also be made by driving ultra-brilliant LEDs at very low current. A hundred μA are nonetheless sensible. In coin cell powered keyring-type LED lights, the resistance of the cell itself is often the only present limiting device. LEDs with built-in series resistors can be found. These might save printed circuit board area, and energy-efficient bulbs are particularly useful when building prototypes or populating a PCB in a way aside from its designers intended. Nonetheless, the resistor value is ready on the time of manufacture, removing one in every of the important thing methods of setting the LED's intensity. Strings of multiple LEDs are usually connected in collection. In one configuration, the source voltage should be greater than or equal to the sum of the person LED voltages; typically the LED voltages add as much as around two-thirds of the availability voltage. A single present-limiting resistor energy-efficient bulbs could also be used for every string.