CURRENT LIMITATION SWITCHING MODE POWER SUPPLY FOR LIGHT EMITTING ELEMENT

摘要

PURPOSE: A switching mode power supply for a LED lamp is provided to regularly maintain an output current by simultaneously detecting an input voltage and an output voltage. CONSTITUTION: A protective circuit unit(110) secludes an over-current and/or the over-voltage included in a AC power. A first rectifier(120) changes a AC voltage passing through the protective circuit unit to a DC voltage. A power supplying unit(130) abandons in a second side of a transformer outputted from the first rectifier. An input voltage comparing unit(140) outputs an input voltage comparing signal with comparing a first standard voltage with a peak voltage of the AC power. A second rectifier rectifies a secondary side voltage of the transformer. An input voltage controller outputs an input voltage controlling signal corresponding to the input voltage comparing signal.