XC9401 series off-line controllers for LED lighting from Torex
The XC9401 series from Torex includes off-line controller ICs for LED lighting. Through optimization of the external components, these ICs can be made to operate in a range from 85 VAC to 270 VAC, as well as by DC input, and a diversity of specifications can be achieved by selecting components appropriate for the circuit configuration. Fixed off-time control is used for the basic control method, and by detecting the current that flows to the external power MOSFET, the current that flows to the LED is monitored to provide a stable power supply for LED lighting. The circuit configuration of type A is designed for the power factor, achieving a high power factor by synchronizing the LED current to the input current (sine wave). In this circuit configuration, a high-capacity, high-withstand voltage electrolytic capacitor is not necessary after the bridge rectifier circuit from the AC input. The input filter removes high-frequency switching noise from the AC line, allowing a small-capacity ceramic capacitor to be used. Type B holds the peak current due to switching that flows to the external-power MOSFET constant, enabling the LED current to be kept constant. By keeping the LED current constant, this circuit configuration makes it possible to achieve a stable light source with high efficiency.