**The NCP1207A/B combines a true current mode modulator and a

demagnetization detector to ensure full borderline/critical Conduction Mode in any load/line conditions and minimum drain voltage switching (Quasi−Resonant operation). Due to its inherent skip cycle capability, the controller enters burst mode as soon as the power demand falls below a predetermined level. As this happens at low peak current, no audible noise can be heard. For the NCP1207A, an internal 8.0μs timer prevents the free−run frequency to exceed 125 kHz (therefore below the 150 kHz CISPR−22 EMI starting limit), while the skip adjustment capability lets the user select the frequency at which the burst foldback takes place. For the NCP1207B, the internal timer duration is reduced to 4.5 s to allow operation at higher frequencies (up to 200 kHz).**

• Free−Running Borderline/Critical Mode Quasi−Resonant Operation

• Current−Mode with Adjustable Skip−Cycle Capability
• No Auxiliary Winding VCC Operation
• Auto−Recovery Overcurrent Protection
• Latching Overvoltage Protection
• External Latch Triggering, e.g. Via Overtemperature Signal
• 500 mA Peak Current Source/Sink Capability
• Undervoltage Lockout for VCC Below 10 V
• Internal 1.0 ms Soft−Start
• Internal 8.0μs Minimum TOFF for NCP1207A,
4.5 s Minimum TOFF for NCP1207B
• Adjustable Skip Level
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• SPICE Models Available for TRANsient Analysis
• These are Pb−Free and Halide−Free Devices

Typical Applications

• AC/DC Adapters for Notebooks, etc.
• Offline Battery Chargers
• Consumer Electronics (DVD Players, Set−Top Boxes, TVs, etc.)
• Auxiliary Power Supplies (USB, Appliances, TVs, etc.)