ON Semiconductor – AC-DC converter controller offers stable valley switching


The NCP1339 from ON Semiconductor is a highly integrated quasi-resonant flyback controller intended for use in rugged, high-performance AC-DC power supplies and power adaptors.

Its quasi-resonant current-mode flyback stage features proprietary valley lock-out circuitry, ensuring stable valley switching. The device also offers a power-saving mode in which no-load power consumption is kept to less than 10mW.

To help the user to implement a rugged converter design, the controller offers several protection features: internal brown-out, non- dissipative over-power protection for a constant maximum output current regardless of the input voltage, and a latched over-voltage protection through a dedicated pin.

• High-voltage start-up current source
• Active input-filter capacitor-discharge circuitry