Soft−Skip Mode Standby PWM Controller with Adjustable Skip Level and External Latch

The NCP1271 represents a new, pin to pin compatible, generation of the successful 7−pin current mode NCP12XX product series. The controller allows for excellent stand by power consumption by use of its adjustable Soft−Skip mode and integrated high voltage startup FET. This proprietary Soft−Skip also dramatically reduces the risk of acoustic noise. This allows the use of inexpensive transformers and capacitors in the clamping network. Internal frequency jittering, ramp compensation, timer−based fault detection and a latch input make this controller an excellent candidate for converters where ruggedness and component cost are the key constraints.

FEATUREs
• Fixed−Frequency Current−Mode Operation with Ramp Compensation and Skip Cycle in Standby Condition
• Timer−Based Fault Protection for Improved Overload Detection
• “Soft−Skip Mode” Technique for Optimal Noise Control in Standby
• Internal High−Voltage Startup Current Source for Lossless Startup
• 5% Current Limit Accuracy over the Full Temperature Range
• Adjustable Skip Level
• Internal Latch for Easy Implementation of Overvoltage and Overtemperature Protection
• Frequency Jittering for Softened EMI Signature
• +500 mA/−800 mA Peak Current Drive Capability
• Sub−100 mW Standby Power can be Achieved
• Pin−to−Pin Compatible with the Existing NCP120X Series
• This is a Pb−Free Device

Typical Applications
• AC−DC Adapters for Notebooks, LCD Monitors
• Offline Battery Chargers
• Consumer Electronic Appliances STB, DVD, DVDR