NCP1338: PWM Controller, Free Running Quasi-Resonant Current Mode

Description: The NCP1338 combines a true current mode modulator...
  • The NCP1338 combines a true current mode modulator and a demagnetization detector which ensures full Borderline/Critical Conduction Mode in any load/line conditions together with minimum drain voltage switching (Quasi-Resonant operation). The transformer core reset detection is done internally, without using any external signal, due to the Soxyless concept. The frequency is internally limited to 130 kHz, preventing the controller from operating above the 150 kHz CISPR-22 EMI starting limit.
    By monitoring the feedback pin activity, the controller enters skip mode as soon as the power demand falls below a predetermined level. As each restart is softened by an internal Soft-Skip™, and as the frequency cannot go below 25 kHz, no audible noise can be heard.
    The NCP1338 also features an efficient protective circuitry which, in presence of an overcurrent condition, disables the output pulses and enters a safe burst mode, trying to restart. Once the default has gone, the device auto-recovers. Also included is a bulk voltage monitoring function (known as brown-out protection), an adjustable overpower compensation, and a VCC OVP. The Fault Timer is reset by any of these conditions, to ensure that the controller immediately restarts when the condition disappear. Finally, an internal 4.0 ms Soft-Start eliminates the traditional startup stress. NCP1338 can be used in applications where the VCC supply voltage is delivered by an external dc voltage source.

    NCP1338 vs NCP1337: When a BO condition is applied, both controllers stop. When the BO condition is removed, NCP1337 doesn't restart if the fault timer has timed out; whereas NCP1338 always restarts (if Vcc is higher than 12 V).
  • Features
  • Overvoltage Protection - rugged design
  • Internal Leading Edge Blanking - Noise immunity
  • Free-Running Borderline/Critical Mode Quasi-Resonant Operation - Reduces EMI and capacitive losses
  • Soft-Skip Mode with Minimum Switching Frequency for Standby - reduces noise and increases efficiency in stand-by mode
  • Current-Mode
  • Auto-Recovery Short-Circuit Protection Independent of Auxiliary Voltage
  • Brown-Out Protection
  • Two Externally Triggerable Fault Comparators (one for a disable function, and the other for a permanent latch)
  • Internal 4.0 ms Soft-Start
  • 500 mA Peak Current Drive Sink Capability
  • 130 kHz Max Frequency
  • Internal Temperature Shutdown
  • Direct Optocoupler Connection
  • Dynamic Self-Supply with Levels of 12 V (On) and 10 V (Off)
  • SPICE Models Available for TRANsient and AC Analysis
  • Pb-Free Device
  • Applications
  • Ac-dc Adapters for Notebooks, etc.
  • Offline Battery Chargers
  • Auxiliary Power Supplies (USB, Appliances, TVs, etc.)
  • End Products
  • Consumer Electronics (DVD Players, Set-Top Boxes, TVs, etc.)
  • Technical Documentation & Design Resources
    Product Change Notification
    Availability and Samples
  • Status: Active
  • Compliance: Pb-free Halide free 
  • Description: PWM Controller, Free Running Quasi-Resonant Current Mode
  • Package Type: SOIC-7
  • Package Case Outline: 751U
  • MSL: 1
  • Container Type: REEL
  • Container Qty: 2500
  • Inventory

  • Market Leadtime (weeks):2 to 4
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  • Packages
  • Topology: Flyback 
  • Control Mode: Current Mode 
  • fsw Typ (kHz): Variable 
  • Stand-by Mode: Yes 
  • UVLO (V): Yes 
  • Short Circuit Protection: Yes 
  • Latch: Yes 
  • Soft Start: Yes 
  • VCC Max (V): 20 
  • Drive Cap. (mA): 500 / 500 
  • Package Type: SOIC-7 
  • ON Semiconductor Full Web Site