Diodes Incorporated AP3128 PWM Controller

Diodes Incorporated AP3128 PWM Controller

Diodes Incorporated AP3128 PWM Controller is a peak-current control and multi-mode (QR+CCM) PWM controller. This controller is optimized for high performance, low standby power, and cost-effective offline flyback converters. The AP3128 is designed to enter burst mode at no-load/light-load and minimizes standby power consumption. This controller features a 105kHz maximum switching frequency that clamps the QR frequency to reduce switching power loss and the minimum frequency avoids audible noise. The AP3128 controller offers multi-mode control, soft start during the startup process, frequency foldback for high average efficiency, and secondary winding short protection with FOCP. Typical applications include a cell phone charger, Power Delivery (PD) application, ATX/BTX auxiliary power, Set-Top Box (STB) power supply, open frame switching power supply.


  • Multi-mode control
  • Quasi-Resonant (QR) operation at high line voltage
  • Continuous Current Mode (CCM) operation at low line voltage
  • Non-audible noise quasi-resonant control
  • Soft start during the startup process
  • Frequency fold back for high average efficiency
  • Constant Over Current Protection (OCP)
  • Secondary winding short protection with FOCP
  • Frequency dithering for reducing EMI
  • Useful Pin fault protection:
    • SENSE pin floating
    • FB/optocoupler open/short
  • Comprehensive system protection feature:
    • VCC Overvoltage Protection (VOVP)
    • Overload Protection (OLP)
  • Brown Out Protection (BNO)


  • 10V to 50V supply voltage range
  • -40°C to 150°C operating junction temperature range
  • 80kHz (CCM mode) oscillation frequency
  • 1µA startup current
  • -800mA to 300mA output current range
  • 550mW Power Dissipation (PD) at TA < 25°C

Block Diagram

Application Circuit

more information: https://www.diodes.com/part/view/AP3128

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Mike is the founder and editor of Electronics-Lab.com, an electronics engineering community/news and project sharing platform. He studied Electronics and Physics and enjoys everything that has moving electrons and fun. His interests lying on solar cells, microcontrollers and switchmode power supplies. Feel free to reach him for feedback, random tips or just to say hello :-)

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