An LED driver is a device that provides a controlled amount of current and voltage to an LED or LED lamp. An LED lamp is a light that contains an array of LEDs configured in an electrical circuit that is designed to operate efficiently. The driver matches the circuit’s voltage and current requirements and controls both current and voltage to ensure proper operation.

 

Light-emitting diodes (LEDs) are two terminal semiconductor devices. An LED’s PN-junction releases photons when a current flows through it in a process called thermoluminescence. The color of an LED is set by the type of material used – which sets the characteristics of the energy band gap specific to the semiconductor.

 

LED drivers receive power from main alternating current (AC) source and is called the primary (PRI) voltage. The driver rectifies this primary voltage to generate a constant DC voltage on the secondary (SEC) side to drive the LED lamp. LED drivers can have bulky iron core transformers to step down the main high voltage to a lower voltage for the LED lamp (12V for example). Most households use a power inverter to step down the voltage for the LED lamp because of their lower cost and small form factor.

 

Many LED drivers contain an extra input to set the LED intensity. This is usually achieved by rapidly switching the power supply to the LED, controlling the on/off ratio (also known as mark/space) of the power supply using a process called pulse width modulation (PWM). LED drivers also have a control loop built into them to maintain a constant current. This enables the LED to work over a large range of voltages with the right intensity output and ensures the LED does not get overdriven, which reduces the bulbs lifespan.  The characteristics of LEDs can change significantly with temperature, which as a result can be damaging unless carefully controlled.

 

In the case where LED driver refers to an individual integrated circuit, it performs the same role as described for a power supply, except that it may support lower LED voltages or a number of different output voltages, and multiple channels of control. Capability is usually described in terms of voltage and current per channel

 

LED drivers are growing in the semiconductor market, matching the demand for efficient long life lighting solutions. It is predicted that by 2020, it will be difficult to buy a light source other than LEDs. By the same time, it is also predicted that the cost will be the same as an incandescent light bulb and consume 85% less energy.