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