Torex Semiconductor’s new XC9401C is a highly efficient, step-down constant current controller for offline LED driver applications that can operate from 85VAC to 270VAC. It uses a constant off-time control method that naturally reduces EMI and provides a stable power supply for LED lighting.
Compared to earlier models the XC9401C benefits from improved ISEN Voltage Accuracy (±2.5%) which helps ensure higher LED current stability and gives the designer more flexibility in the selection of external components.
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 XC9401C 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 XC9401C can offer at the same time a high efficiency ( > 82%) and a high power factor ( > 0.9). LED dimming can be adjusted via a PWM signal at the CE/DIM pin. The average LED current can be set within the range of 1% to 100% by controlling the pulse width of the PWM signal.
The XC9401C is also tested with certified transformers that fulfil the European regulations regarding isolation and utilises the lower cost SOT25 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.