Power chip

The NCP1236 is a new fixed-frequency current-mode controller with dynamic self-supply (DSS) capability. This device is pin compatible with the previous NCP12xx family. The DSS feature activates an internal startup current source to power the controller during transients, greatly simplifying the design of auxiliary power supplies and VCC capacitors. Due to frequency foldback, the controller has excellent energy efficiency at light load conditions while achieving very low standby power consumption. With internal frequency jittering, slope compensation, and a versatile latch input, this controller is ideal for converters where component cost is a key limiting factor. Additionally, the controller includes a novel high-voltage circuit that combines a start-up current source and an undervoltage detector capable of sensing input voltage from a rectified AC line or DC filtered bulk voltage. This high voltage sensing circuit is also used for over power protection purposes. Overpower protection, overload protection, and other protection features increase the safety and reliability of the end application.