NCP1236

DATA SHEET www.onsemi.com Fixed Frequency Current Mode Controller for Flyback Converters NCP1236 The NCP1236 is a new fixed−frequency current−mode controller featuring Dynamic Self−Supply (DSS). This device is pin−to−pin compatible with the previous NCP12xx families. The DSS function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal startup current source to supply the controller during transients. Due to frequency foldback, the controller exhibits excellent efficiency in light load condition while still achieving very low standby power consumption. Internal frequency jittering, ramp compensation, and a versatile latch input make this controller an excellent candidate for converters where components cost is the key constraints. In addition, the controller includes a new high voltage circuitry that combines a start−up current source and a brown−out detector able to sense the input voltage either from the rectified ac line or the dc filtered bulk voltage. The high voltage sensing circuitry is used for the overpower protection purposes as well. Overpower protection, overload protection, and next protective features increases safety level of the final application. Finally, due to a careful design, the precision of critical parameters is well controlled over the entire temperature range (−40C to +125C). MARKING DIAGRAM SOIC−7 CASE 751U 8 36Xff ALYW G 1 36Xff = Specific Device Code X = A, B, C or D ff = 65 or 100 A = As...