The NCP1239 is a fixed-frequency current-mode controller featuring a high-voltage start-up current source to provide a quick and lossless power-on sequence. 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.

FEATUREs
• Fixed-Frequency 65-kHz or 100-kHz Current-Mode Control
   Operation
• Frequency Foldback Down to 26 kHz and Skip Mode to
   Maximize Performance in Light Load Conditions
• Adjustable Over Power Protection (OPP) Circuit
• High-Voltage Current Source with Brown-Out (BO) Detection
• Internal Slope Compensation
• Internal Fixed Soft-Start
• Frequency Jittering in Normal and Frequency Foldback Modes
• 64-ms Timer-Based Short-Circuit Protection with Auto-Recovery
   or Latched Operation
• Pre-Short Ready for Latched OCP Versions
• Latched OVP on VCC – Autorecovery for C and E Versions
• Latched OVP/OTP Input for Improved Robustness
• 35-V VCC Operation
• ±500 mA Peak Source/Sink Drive Capability
• Internal Thermal Shutdown
• Extremely Low No-Load Standby Power
• Pin-to-Pin Compatible with the Existing NCP1236/1247 Series
• These Devices are Pb-Free and are RoHS Compliant

Typical Applications
• AC-DC Converters for TVs, Set-Top Boxes and Printers
• Offline Adapters for Notebooks and Netbooks