Peeragarhi, New Delhi, Delhi
GST No. 07AAPFB5172M1ZY
Inelectronics, anLED circuitorLED driveris anelectricalcircuitused to power alight-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. Thevoltage dropacross an LED is approximately constant over a wide range of operating current; therefore, a small increase in applied voltage greatly increases the current. Very simple circuits are used for low-power indicator LEDs. More complex,current sourcecircuits are required when driving highpower LEDs for illumination to achieve correct current regulation.
Basic of Led Driver
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-efficient, because energy is dissipated in the resistor as heat.
An LED has a voltage drop specified at the intended operating current.Ohm's lawandKirchhoff's circuit lawsare used to calculate the appropriate resistor value, by subtracting the LED voltage drop from the supply voltage and dividing by the desired operating current. With a sufficiently high supply voltage, multiple LEDs in series can be powered with one resistor.
If the supply voltage is close or equal to the LED forward voltage, then no reasonable value for the resistor can be calculated, so some other method of current limiting is used.Power source considerations Led Driver
The voltage versus current characteristics of an LED are similar to anydiode. Current is approximately anexponential functionof voltage according to theShockley diode equation, and a small voltage change may result in a large change in current. If the voltage is below or equal to the threshold no current flows and the result is an unlit LED. If the voltage is too high the current exceeds the maximum rating, overheating and potentially destroying the LED.
As an LED heats up, its voltage drop decreases (band gap decrease). This can encourage the current to increase.