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NCP1251 - Current-Mode PWM Controller

Description

The controller ground.

Hooking an optocoupler collector to this pin will allow regulation.

A resistive divider from the auxiliary winding to this pin sets the OPP compensation level.

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.
  • Re.

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Datasheet preview – NCP1251

Datasheet Details

Part number NCP1251
Manufacturer onsemi
File Size 426.87 KB
Description Current-Mode PWM Controller
Datasheet download datasheet NCP1251 Datasheet
Additional preview pages of the NCP1251 datasheet.

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Full PDF Text Transcription

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DATA SHEET www.onsemi.com Current-Mode PWM Controller for Off-line Power Supplies NCP1251 The NCP1251 is a highly integrated PWM controller capable of delivering a rugged and high performance offline power supply in a tiny TSOP−6 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.
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