NCP1124: High Voltage Switching Regulator for Offline SMPS

Datasheet: High Voltage Switcher for Offline Power Supplies
Rev. 3 (189kB)
Product Overview
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The NCP1124 switcher offers everything needed to build reliable and compact AC-DC switching power supplies with minimal surrounding elements. Incorporating an avalanche rated 650 V MOSFET, converters built with the NCP1124 can be safely designed for international conditions without jeopardizing the overall reliability.

The NCP1124 implements peak current mode control with adjustable ramp compensation that ensures stability in Continuous Conduction Mode (CCM) operation. With an external resistor, the maximum peak current is adjustable, allowing the designer the ability to inject ramp compensation to stabilize CCM power supplies.

A short circuit fault condition is independently detected from the auxiliary winding voltage resulting in improved short circuit protection with true overload detection. The Source pin provides access to the MOSFET source, allowing for overpower compensation.

With a supply range up to 26 V, the switcher also provides a jittered 65 kHz or 100 kHz switching frequency operated in peak current mode control. When the power on the secondary side starts to decrease, the switcher 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.
Features   Benefits
  • 650 V Avalanche Rated MOSFET
  • Rugged MOSFET for robust design
  • Fixed−Frequency 65 or 100 kHz Current−Mode Control with Adjustable Internal Ramp Compensation
  • Ability to scale for efficiency or size
  • Frequency Foldback Down to 26 kHz and Skip−Cycle for Light Load Efficiency
  • Eliminate acoustic noise and improved efficiency at light loads
  • Adjustable Current Limit with External Resistor
  • Scale for various designs 5W~20W
  • 50 ms Timer-Based Auto-Recovery Short-Circuit Protection
  • Provides more robust protection without worrying about the coupling of the aux winding
  • Frequency Jittering in Normal and Frequency Foldback Modes
  • Improved efficiency at light load / Improved EMI over the entire load
  • Option for Auto-Recovery or Latched Short-Circuit Protection
  • Flexible protection options
  • Less than 100 mW Standby Power at High Line
  • EPS 2.0 Compliant
Applications   End Products
  • Power Supply
  • Power supply for DVD, STB, CD-Player
  • Aux supply for TV, USB, Appliance
Technical Documentation & Design Resources
Design Notes (2) Package Drawings (1)
Data Sheets (1)  
Budgetary Price/Unit
Case Outline
NCP1124AP100G Obsolete
Halide free
NCP1124, 9-Ohm, Latch PDIP-8 626B NA Tube 50  
NCP1124AP65G Obsolete
Halide free
NCP1124, 9-Ohm, Latch PDIP-8 626B NA Tube 50  
NCP1124BP100G Obsolete
Halide free
NCP1124, 9-Ohm, Auto-recovery PDIP-8 626B NA Tube 50  
NCP1124BP65G Obsolete
Halide free
NCP1124 PDIP-8 626B NA Tube 50  
Market Leadtime (weeks) : Contact Factory
Market Leadtime (weeks) : Contact Factory
Market Leadtime (weeks) : Contact Factory
Market Leadtime (weeks) : Contact Factory
Case Outlines
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