In electronics, an LED circuit or LED driver is an electrical circuit used to power a light-emitting diode (LED). The circuit must provide sufficient current to light the LED at the required brightness, but must limit the current to prevent damaging the LED. The voltage drop across a lit LED is approximately constant over a. The simplest circuit to drive an LED is through a series resistor. It is commonly used for indicators and digital displays in many consumer appliances. However, this circuit is not energy. The voltage versus current characteristics of an LED is similar to any. Current is approximately an of voltage according to the Series are a simple way to stabilize the LED current, but energy is wasted in the resistor.Miniature indicator LEDs. LEDs are often arranged in ways such that each LED (or each string of LEDs) can be individually turned on and off.Direct drive is the simplest-to-understand approach—it uses many independent single-LED (or single-string) circuits. For example, a person could. An active constant is commonly used for high power LEDs, stabilizing light output over a wide range of input voltages which might increase the useful life of batteries. Active constant current is typically regulated using a Strings of multiple LEDs are normally connected. In one configuration, the source voltage must be greater than or equal to the sum of the individual LED voltages; typically the LED. Unlike, which illuminate regardless of the electrical, will only light with the correct electrical polarity. When the voltage across the is in the correct direction, a significant current flows and the device is said to. In, an LED circuit or LED driver is an used to power a (LED). The circuit must provide sufficient current to light the LED at the required brightness, but must limit the current to prevent damaging the LED. The across a lit LED is approximately constant over a wide range of operating current; therefore, a small increase in applied voltage greatl. LED uses fall into five major categories: • Visual signals where light goes more or less directly from the source to the human eye, to convey a message or meaning• where light is reflected from objects to give visual response of these objects.