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NCP1235: Controller, Fixed Frequency, Current Mode, for Flyback Converters

Datasheet: Fixed Frequency Current Mode Controller for Flyback Converters
Rev. P0 (237kB)
Product Overview
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The NCP1235 is a new fixed-frequency current-mode controller featuring Dynamic Self-Supply (DSS). This device is pin-to-pin compatible with the previous NCP12xx families.
The DSS function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal startup current source to supply the controller during transients.
Due to frequency foldback, the controller exhibits excellent efficiency in light load condition while still achieving very low standby power consumption. Internal frequency jittering, ramp compensation, and a versatile latch input make this controller an excellent candidate for converters where component cost is the key constraint.
In addition, the controller includes a new high voltage circuitry that combines a startup current source and a brown-out detector able to sense the input voltage either from the rectified ac line or the dc filtered bulk voltage. The high voltage sensing circuitry is used for the overpower protection purposes as well. Overpower protection, overload protection, and other protective features increase the safety and reliability of the final application.
Features   Benefits
  • Frequency Foldback then Skip Mode in light load and standby conditions
  • High efficiency in light and no load conditions
  • High voltage current source with brown-out detection and dynamic self-supply
  • Directly powered from the high voltage rail with integrated brown-out sensing to detect low input voltage.
  • Frequency Jittering
  • Helps pass EMI requirements by spreading out the energy content of frequency peaks
  • 16.0 ms Soft-Start
  • Minimizes the stress on power components
  • Adjustable Overpower Compensation
  • Monitors the input voltage to limit the amount of power being delivered by the converter
  • Latched Timer-Based Overload Protection
  • Protects against overcurrent
Applications   End Products
  • AC-DC Adapters
  • Consumer Electronics Power Supplies
  • Auxiliary/Housekeeping power supplies
  • Notebooks
  • LCD TVs
  • Printers
Technical Documentation & Design Resources
Data Sheets (1) Package Drawings (1)
Budgetary Price/Unit
Case Outline
NCP1235AD065R2G Obsolete
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NCP1235 SOIC-7 751U 1 260 Tape and Reel 2500  
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