Diodes Incorporated
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Active Clamp Flyback (ACF) Operation, embedded LDO for full range USB PD3.0 (3.3~21V), Optimized for 45~65W Output Power with HV start-up circuit

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The AP3306 is a highly integrated Active Clamp Flyback (ACF) controller optimally designed for offline power supplies to meet ultra-low standby power, high power density, and comprehensive protection requirements. The controller realizes non-complimentary high-low-side control mechanisms to achieve Leakage Energy Recycling and Zero Voltage Switching (ZVS) for supreme-efficiency performance. The AP3306 provides a high-voltage start-up function through the HV pin, reducing standby loss. Moreover, the AP3306 integrates a VCCL LDO circuit, allowing the LDO to regulate the wide range VCCL to an acceptable value. This makes the AP3306 an ideal candidate for wide-range output-voltage applications, such as USB-PD. The built-in frequency dithering function greatly eases EMI design as well. At no load or light load, the IC will enter burst mode to minimize standby power consumption. The minimum switching frequency (about 22kHz) is set to avoid audible noise. When the load increases, the IC will enter ACF mode with frequency foldback to improve system efficiency and EMI performance. The maximum switching frequency (about 130kHz or 200kHz optional) is set to clamp the switching frequency to reduce switching power loss. Comprehensive protection features are included, such as Brown-Out Protection (BNO), Cycle-by-Cycle Overcurrent Protection (OCP), VCC Overvoltage Protection (VOVP), Secondary-Side Output OVP (SOVP) and UVP (SUVP), internal Overtemperature Protection (OTP), Overload Protection (OLP), and Pin Fault Protection.


  • Active Clamp Flyback Topology with Recycled Leakage Energy and Pseudo Zero Voltage Switching Functions
  • High-Voltage Startup
  • Embedded VCC LDO for VCCL Pin to Guarantee Wide Range Output Voltage
  • Non-Audible-Noise Quasi-Resonant Control
  • Soft Start During Startup Process
  • Frequency Foldback for High Average Efficiency
  • Secondary Winding Short Protection with FOCP
  • Frequency Dithering for Reducing EMI
  • X-CAP Discharge Function
  • Useful Pin Fault Protection
  • CS Pin Floating Protection
  • FB/Opto-Coupler Open/Short Protection
  • Comprehensive System Protection Features:
    • VCC Overvoltage Protection (VOVP)
    • Overload Protection (OLP)
    • Brown-Out Protection (BNO)
    • Secondary-Side OVP (SOVP) and UVP (SUVP)
  • Packaged in the SO-10 (Type A1)
  • 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/


  • Smart Phone Quick Chargers
  • Notebook Computer Adapters
  • High Power Density Adapters/Chargers: 30W/inch3
  • Compact Switching AC-DC Adapter/Charger
  • Suitable for Variable Output Voltage Applications (USB-PD, QC, SCP, VSCP, VOOC, AFC, etc.)
  • ATX/BTX Auxiliary Power Applications
  • Set-Top Box (STB) Power Supplies
  • Open Frame Switching Power Supplies

Product Specifications

Product Parameters

Operation Mode ACF
HV Start-UpCircuit Yes
Vcc_MAX(V) 120 (VCCH)
UVLOThresholdon/off (V) 15.8/6.5 V
Gate OutputCurrent (mA) -0.375 mA
Maximum OscillationFrequency (kHz) 125 (ACF mode) kHz
BNO Auto-Recover
Release Date 202108

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