What is an LED Driver?
To be able to deliver it’s designed light output, consistent with reasonable lifetime, an
LED requires a controlled source of DC power.
An LED is essentially a semiconductor diode and, as such has an anode and a cathode
(positive and negative connections). The power supply for a LED must deliver ripple free
DC (direct current), not AC (alternating current). This can be from a battery (eg, as in a
torch), or via a LED DRIVER, which itself is commonly supplied from AC mains power.
The vast majority of drivers used to power LED lighting in domestic, commercial and
industrial situations have mains power input, and a controlled constant voltage or
constant current DC output which must comply with the specifications as set out by the
LED manufacturer. This output must be stable in regard to time, ambient temperature
and load, or the performance and life of the LED will suffer. Fortunately, this is easily
achievable with modern electronics.
Like any electronic device, an LED driver is designed to work up until it’s maximum
operating temperature is reached. At or just before this point (case temperature
typically 90-100C), internal sensors invoke a protection mechanism and shut the output
down so that the driver does not self destruct. The driver may re-start when the
temperature drops below a pre-determined figure, or upon re-start. Care must
particularly be taken when mounting a driver in a sealed enclosure where lack of free air
circulation can de-rate the output considerably.
In the event that the output current is exceeded or the output is short-circuited, the
driver may current limit or shut down. Auto recovery will occur when the fault is
Different manufacturers use different methods of input protection.Typically, mains
input LED drivers offer an input voltage range of 100 – 305V AC, 47 – 63Hz (or 130 –
430V DC). This enables these models to be used in countries which have different mains
supply voltages and frequencies Some drivers