The NCP1246 is a new fixed−frequency current−mode controller featuring the 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 etc. This device contains a special HV detector which detect the application unplug from the AC input line and triggers the X2 discharge current. This HV structure allows the brown−out detection as well.
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 to reach the extremely low no load input power consumption via “sleeping” whole device and thus minimize the power consumption of the control circuitry.

FEATUREs
• Fixed−Frequency Current−Mode Operation (65 kHz and 100 kHz frequency options)
• Frequency Foldback then Skip Mode for Maximized Performance in Light Load and Standby Conditions
• Timer−Based Overload Protection with Latched (Option A) or Auto−Recovery (Option B) Operation
• High−voltage Current Source with Brown−Out Detection and Dynamic Self−Supply, Simplifying the Design of the VCC Circuitry
• Frequency Modulation for Softened EMI Signature
• Adjustable Overpower Protection Dependant on the Bulk Voltage
• Latch−off Input Combined with the Overpower Protection Sensing Input
• VCC Operation up to 28 V, With Overvoltage Detection
• 500/800 mA Source/Sink Drive Peak Current Capability
• 10 ms Soft−Start
• Internal Thermal Shutdown
• No−Load Standby Power < 30 mW
• X2 Capacitor in EMI Filter Discharging Feature
• These Devices are Pb−Free and Halogen Free/BFR Free

Typical Applications
• AC−DC Adapters for Notebooks, LCD, and Printers
• Offline Battery Chargers
• Consumer Electronic Power Supplies
• Auxiliary/Housekeeping Power Supplies
• Offline Adapters for Notebooks