Low−Standby High Performance PWM Controller

Housed in SO−16 the NCP1239 represents a major leap toward ultra−compact Switch Mode Power Supplies specifically tailored for medium to high power off−line applications, e.g. notebook adapters. The NCP1239 offers everything needed to build a rugged and efficient power supply, including a dedicated event management to drive a Power Factor Correction (PFC) front−end circuitry.
The circuit disables the front−end PFC stage while still in fault or standby conditions by interrupting the PFC controller powering for improved no−load consumption figures. As soon as normal operating mode recovers, the NCP1239 feeds back the PFC that wakes−up.

FEATUREs
• Current−Mode Operation with Internal Ramp Compensation
• Internal High−Voltage Current Source for loss−less Startup
• Adjustable Skip−Cycle Capability
• Selectable Soft−Start Period
• Internal Frequency Dithering for Improved EMI Signature
• Go−to−Standby Signal for PFC Front−Stage
• Large VCC Operation from 12.2 V to 36 V
• 500 mV Overcurrent Limit
• 500 mA/−800 mA Peak Current Capability
• 5 V/10 mA Pinned−out Reference Voltage
• Adjustable Switching Frequency up to 250 kHz.
• Overload Protection Independent of the Auxiliary VCC
• Adjustable Over Power Compensation (NCP1239F)
• Programmable Maximum Duty Cycle (NCP1239V)
• Pb−Free Packages are Available*

Typical Applications
• High Power AC/DC Adapters for Notebooks etc.
• Offline Battery Chargers
• Telecom and PC Power Supplies
• Flyback Applications (NCP1239F) and Forward Applications
   (NCP1239V)