ON Semiconductor NCP124x Fixed
Frequency Current Mode Controllers
ON Semiconductor's NCP124x Fixed Frequency Current Mode Controllers are new fixed-frequency current-mode controllers featuring Dynamic Self-Supply. This function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal start-up current source to supply the controller during start-up, transients, latch, stand-by etc. These devices contain a special HV detector which detects the application unplug from the AC input line and triggers the X2 discharge current. The HV structure also includes brown-out detection circuitry (in NCP1246). It features a timer-based fault detection that ensures the detection of overload and an adjustable compensation to help keep the maximum power independent of the input voltage.