Diodes Incorporated

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Multi-Mode PWM Controller with Light-Load High Efficiency and Peak-Power Mode

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The AP3129 is a highly integrated multi-mode peak current controller, which specially provides high efficiency at light load for IoT application. Meanwhile, the AP3129 features a proprietary audible noise elimination technology to ease the acoustic noises from electronic and magnetic components.

The AP3129 is a multi-mode controller, which changes operating mode according to load conditions. Under heavy-load condition, the device operates in CCM (continuous-conduction mode) with a fixed switching frequency of 65kHz, which is helpful to system design with small transformer size. When the loading is decreasing, it enters QR (Quasi Resonant) or Green mode with valley switching for the higher power conversion efficiency. At light load or no load, the IC will operate with its proprietary burst mode to minimize power consumption with the minimum switching frequency (about 22kHz).

The controller architecture is designed to authorize a transient peak power excursion for peak load. It means the frequency can be increased from 65kHz to 130kHz until the peak event disappears.

In addition, piecewise linear line compensation ensures accurate constant output power limit over an entire line voltage range.


  • Multiple Operation Modes
    • 130kHz Maximum Frequency for Peak Load
    • 65kHz Fixed-Frequency CCM Operation for Full Load
    • 80kHZ Maximum Clamping Frequency for QR Mode
    • Valley Switching Operation in Green Mode
    • Burst Mode Control for Light Load
  • High Efficiency at Light Load (> 90% Efficiency at 10% Load)
  • Proprietary Audible Noise Elimination Technology
  • Soft Start During Startup Process
  • Internal Slope Compensation
  • Frequency Dithering for Reducing EMI
  • VCC Maintain Mode
  • Low No-Load Consumption
  • Comprehensive System Protection Features
    • Secondary Winding Short Protection
    • VCC Overvoltage Protection (VOVP)
    • Line Overvoltage Protection (LOVP)
    • Overload Protection (OLP)
    • Cycle-by-Cycle Overcurrent Protection
    • Pin-Fault Protection
    • Brown-In/Out Protection (BNI/BNO)
    • Secondary Side OVP (SOVP) and UVP (SUVP)
    • Internal OTP
  • SOT26 (Type CJ) is Available
  • Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
  • Halogen and Antimony Free. “Green” Device (Note 3)
  • For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/104/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. https://www.diodes.com/quality/product-definitions/


  • IoT (Internet of Thing) offline power
  • Home appliances: smart speakers, AC fans, rice cookers, shavers, milk machines
  • TV/Monitor standby power
  • AC/DC adapters or quick chargers

Product Specifications

Product Parameters

Operation Mode QR/CCM
HV Start-UpCircuit N/A
Vcc_MAX(V) 32
UVLOThresholdon/off (V) 18/6.3 V
Gate OutputCurrent (mA) -0.6 mA
Maximum OscillationFrequency (kHz) 65 (CCM mode) / 130 (Peak Load) kHz
BNO Auto-Recovery
LOVP Auto-Recovery
Release Date 202307

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