Onsemi NCP1251

Description

Low input, Ultra wide AC input range, E-meter power supplyThe NCP1251 is a highly integrated PWM controller capable ofdelivering a rugged and high performance offline power supply in atiny TSOP−6 package. With a supply range up to 28 V, the controllerhosts a jittered 65 kHz or 100 kHz switching circuitry operated in peakcurrent mode control. When the power on the secondary side starts todecrease, the controller automatically folds back its switchingfrequency down to a minimum level of 26 kHz. As the power furthergoes down, the part enters skip cycle while limiting the peak current.Over Power Protection (OPP) is a difficult exercise especially whenno−load standby requirements drive the converter specifications. TheON proprietary integrated OPP lets you harness the maximumdelivered power without affecting your standby performance simplyvia two external resistors. A latched Over Voltage Protection (OVP) iscombined on the same pin. For ease of implementation, a latched OVPalso monitors the VCC line. They offer an efficient protection in caseof optocoupler destruction or adverse open loop operation.Finally, a timer−based short−circuit protection offers the bestprotection scheme, letting you precisely select the protection trip pointirrespective of a loose coupling between the auxiliary and the powerwindings.

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 LoadConditions
• 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
• Latched or Auto−Recovery OVP Protection on VCC
• +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

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

More information

• Datasheet
• IC product information