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The NCP1252 controller offers everything needed to build cost−

effective and reliable ac−dc switching supplies dedicated to ATX

power supplies. Thanks to the use of an internally fixed timer,

NCP1252 detects an output overload without relying on the auxiliary

Vcc. A Brown−Out input offers protection against low input voltages

and improves the converter safety. Finally a SOIC−8 package saves

PCB space and represents a solution of choice in cost sensitive project.

特性 Features

• Peak Current Mode Control

• Adjustable Switching Frequency up to 500 kHz

• Jittering Frequency ±5 of the Switching Frequency

• Latched Primary Over Current Protection with 10 ms Fixed Delay

• Delay Extended to 150 ms in E Version

• Delayed Operation Upon Start−up via an Internal Fixed Timer

(A, B and C versions only)

• Adjustable Soft−start Timer

• Auto−recovery Brown−Out Detection

• UC384X−like UVLO Thresholds

• Vcc Range from 9 V to 28 V with Auto−recovery UVLO

• Internal 160 ns Leading Edge Blanking

• Adjustable Internal Ramp Compensation

• +500 mA / –800 mA Source / Sink Capability

• Maximum 50 Duty Cycle: A Version

• Maximum 80 Duty Cycle: B Version

• Maximum 65 Duty Cycle: C Version

• Maximum 47.5 Duty Cycle: D & E Versions

• Ready for Updated No Load Regulation Specifications

• SOIC−8 and PDIP−8 Packages

• These are Pb−Free Devices

Typical Applications

• Power Supplies for PC Silver Boxes, Games Adapter...

• Flyback and Forward Converter