LEDs operate from DC and are relatively easy to work with but there are three points that help understand regarding the role of an LED driver:
- Voltage: LEDs in a backlight will be wired in series so in each LED requires 3v and there are 20 LEDs the voltage required will be 60v.
- Current: The driver will maintain a constant current to the LED’s.
- Brightness control: Two normal methods to control brightness are by varying the current or using a technique called Pulse Width Modulation (PWM*).
For a display system design perspective the complex work is done by the LED driver design and usage is as straightforward as following the connection specifications.
* PWM creates the impression of lower light by switching the LEDs on/off but at a frequency faster than our perception. Using PWM the brightness can be lower than achievable by simply reducing the current.