Power supply unit, light emitting apparatus and dimming method thereof

A power supply unit with a dimming function which is adapted for a light emitting apparatus including a power system is provided. The power supply unit includes at least one output channel, a power stage, a detecting unit, and a micro controller unit (MCU). The power stage receives a first output of the power system and provides a first signal. The detecting unit detects a second output of the power system and provides a second signal. The MCU receives the first signal and the second signal, controls the at least one output channel, and is programmed to set a dimming ratio for the at least one output channel according to the first signal and the second signal. Furthermore, a light emitting apparatus and a dimming method are also provided.