By ON Semiconductor 137


ON Semiconductor's® NCP1244 and NCP1246 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 startup current source to supply the controller during start-up, transients, latch, stand-by, and more. 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. 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 the robust power-supply designs.

A dedicated OFF mode allows it to reach the extremely-low, no-load input power consumption via sleeping the whole device, and thus minimizing the power consumption of the control circuitry.

  • Frequency foldback and skip mode
  • Timer-based overload protection with latched (A version) or auto-recovery (B version) operation
  • High-voltage startup with Dynamic Self Supply (DSS)
  • Integrated brown-out detection (in NCP1246)
  • Frequency Modulation
  • Internal Frequency Jittering
  • Adjustable over-power protection
  • Latch off input
  • Integrated X2 capacitor discharge
  • Power-saving off mode when used with NCP4353 or NCP4354
  • AC-DC adapters
  • LCD TV power supplies
End Products
  • Notebook computers
  • LCD TV power supplies