Digital lighting technologies, i.e. illumination based on semiconductor light sources, such as light-emitting diodes (LEDs), offer a viable alternative to traditional fluorescent, HID, and incandescent lamps. Functional advantages and benefits of LEDs include high energy conversion and optical efficiency, durability, lower operating costs, and many others. Recent advances in LED technology have provided efficient and robust full-spectrum lighting sources that enable a variety of lighting effects in many applications. Under various conditions, such as start up, mains brownout, or turn off, output current in a LED driver can overshoot resulting in flicker or flash from the LED(s) and potential LED failure due to excessive current. This can be due to lack of control over the timing of the power supplies (for the power stage integrated circuits (ICs)) and reference ICs, and can also be due to initial conditions of regulator ICs, etc., of the LED driver. In traditional LED drivers, the current reference value is either a fixed value or merely controlled by a dimming interface. At start up, the output current of the driver is zero. Because of the large error between the driver output current and the current reference signal, a large feedback signal is provided. When the driver suddenly reacts to such a very large feedback signal, the output current of the driver rises at a rapid rate. This may lead to overshoot of the driver output current, causing the LED light output to flash and flicker. Also, depending on the initial condition of the inputs of regulator ICs, driver can start with high output current.
Thus, there is a need in the art to control the power supplies of the various power stage ICs, and to control reference values and/or initial conditions of the feedback control circuits of the LED driver.