App note from Aimtec on dimming LEDs. Link here
With the phenomenal growth of the LED lighting market, there has been a natural growth in demand for highly efficient and controlled LED drivers. Applications from ‘smart’ street lights, flashlights, digital signage and many others require not only highly regulated currents, but in many cases dimming capability in order to sustain the energy efficient scheme and end use flexibility behind LED design.
As there are several ways to achieve dimming of an LED, we describe here the main methods that are used to provide dimming for LED’s from a switch mode LED driver.