The NCP1250 is a highly integrated PWM controller capable of
delivering a rugged and high performance offline power supply in a
tiny TSOP−6 or PDIP−8 package. With a supply range up to 28 V, the
controller hosts a jittered 65 kHz or 100 kHz switching circuitry
operated in peak current mode control. When the power on the
secondary side starts to decrease, the controller automatically folds
back its switching frequency down to a minimum level of 26 kHz. As
the power further goes down, the part enters skip cycle while limiting
the peak current.
Over Power Protection (OPP) is a difficult exercise especially when
no−load standby requirements drive the converter specifications. The
ON proprietary integrated OPP lets you harness the maximum
delivered power without affecting your standby performance simply
via two external resistors. An Over Voltage Protection input is also
combined on the same pin and protects the whole circuitry in case of
optocoupler failure or adverse open loop operation.
Finally, a timer−based short−circuit protection offers the best
protection scheme, letting you precisely select the protection trip point
irrespective of a loose coupling between the auxiliary and the power windings.

Features
• Fixed−Frequency 65 or 100 kHz Current−Mode Control Operation
• Internal and Adjustable Over Power Protection (OPP) Circuit
• Frequency Foldback Down to 26 kHz and Skip−Cycle in Light Load
Conditions
• Internal Ramp Compensation
• Internal Fixed 4 ms Soft−Start
• 100 ms Timer−Based Auto−Recovery Short−Circuit Protection
• Frequency Jittering in Normal and Frequency Foldback Modes
• Option for Auto−Recovery or Latched Short−Circuit Protection
• OVP Input for Improved Robustness
• Up to 28 V VCC Operation
• +300 mA/−500 mA Source/Sink Drive Capability
• Less than 100 mW Standby Power at High Line
• EPS 2.0 Compliant
• These are Pb−Free Devices

Typical Applications
• ac−dc Converters for TVs, Set−top Boxes and Printers
• Offline Adapters for Notebooks and Netbooks