Constant-current controller serves offline LED driver applications



The XC9401 is a highly efficient step-down constant-current controller for offline LED driver applications that can operate from 85VAC to 270VAC. The XC9401 uses a constant off-time control method that naturally reduces EMI. To filter high-frequency switching noise from the AC line, a low cost ceramic capacitor can be used instead of a large electrolytic capacitor. The XC9401 also includes circuits that protect against excessive temperature, over-current (on a cycle-by-cycle basis), low input voltage (UVLO) and VDD over-voltage. Due to its architecture, the XC9401 can offer at the same time a high efficiency ( > 82%) and a high power factor ( > 0.9). LED dimming can also be adjusted via a PWM signal at the CE/DIM pin. The width of the CE/DIM pulse controls the average LED current and changes the brightness. The XC9401 is also tested with certified transformers that fulfil the European regulations regarding isolation and utilises the low cost SOT26 package that can be deployed in a variety of circuit configurations including Isolated Flyback and Non-isolated Buck. A fully populated EVB can be provided upon request. Torex Semiconductor