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QR/CCM Operation with HV start

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The AP3128 is a peak-current control, multi-mode (QR+CCM) PWM controller optimized for high performance, low standby power and cost-effective offline flyback converters. At no load or light load, the IC will enter burst mode to minimize standby power consumption. The minimum switching frequency is set to avoid audible noise. When the load increases, the IC will enter QR mode with frequency foldback to improve system efficiency and EMI performance. The maximum switching frequency about 105kHz is set to clamp the QR frequency to reduce switching power loss. Furthermore, the frequency dithering function is built in to reduce EMI emission. Internal piecewise linear line compensation ensures constant output power limit over the entire universal line voltage range. Comprehensive protection features are included, such as brown-out protection, cycle-by-cycle current limit (OCP), VCC Overvoltage Protection (VOVP), Secondary-side Output OVP (SOVP) and UVP (SUVP), internal OTP, Overload Protection (OLP), and pins’ fault protection.


  • 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 Startup Process
  • Frequency Fold Back for High Average Efficiency
  • Constant Over Current Protection
  • Secondary Winding Short Protection with FOCP
  • Frequency Dithering for Reducing EMI
  • Useful Pin Fault Protection:
    • SENSE Pin Floating
    • FB/Opto-Coupler Open/Short
  • Comprehensive System Protection Feature:
    • VCC Overvoltage Protection (VOVP)
    • Overload Protection (OLP)
  • Brown Out Protection (BNO)
  • Secondary Side OVP (SOVP) and UVP (SUVP)
  • Totally Lead-Free & Fully RoHS Compliant 
  • Halogen and Antimony Free. “Green” Device 
  • For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. https://www.diodes.com/quality/product-definitions/


Product Specifications

Product Parameters

Operation Mode QR/CCM
HV Start-UpCircuit Yes
Vcc_MAX(V) 60
UVLOThresholdon/off (V) 15.8/6.5 V
Gate OutputCurrent (mA) -0.375 mA
Maximum OscillationFrequency (kHz) 80 (CCM mode)/105 (QR mode) kHz
BNO Auto-Recover
Release Date 202109

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