Primary-side controlled switch-mode power supply controller for driving LED with constant current and method thereof

摘要

The present invention discloses a primary-side controlled switch-mode power supply controller for driving LED with constant current and method thereof as well as an apparatus for controlling switch-mode power supply having the switch-mode power supply controller. The switch-mode power supply controller includes an input dimming phase detection circuit, a multiplier, a turn-on signal control circuit, a zero-crossing detection circuit, a comparator, a trigger and a driving circuit. The circuit controls to drive LED with constant current by means of a primary-side controlled method. The circuit realizes the triac dimming function, ensures a constant output current regardless of a high voltage or a low voltage, and obtains a high power factor. The direct use of the isolation transformer improves the safety of the circuit, and simplifies the peripheral circuit, thereby reducing the cost of the circuit and minimizing the size of the PCB layout, which is favorable in minimizing the product.