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The AP3303 is a peak-current control, Quasi-Resonant (QR) PWM controller which is specially designed for offline power supply that requires ultra-low standby power, high-power density and comprehensive protection. It can coordinate with secondary side USBPD or quick charger controller which can provide a flyback charger solution.

At no load or light load, the IC will enter the burst mode to minimize standby power consumption. The minimum switching frequency (typical: 24kHz) is set to avoid the 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 (typical: 120kHz) is set to clamp the QR frequency to reduce switching power loss. Furthermore, the frequency dithering function is built in to reduce EMI emission.

The AP3303 provides an inner high-voltage start-up function through HV pin which can reduce the standby loss. Moreover, The AP3303 integrates a VCC LDO circuitry, allowing the LDO to regulate the wide range VCC_IN to an acceptable value. This makes the AP3303 to be a good choice in wide range output voltage application.

Internal piecewise linear line compensation ensures constant output power limit over entire universal line voltage range.

Comprehensive protection features are included, such as brown out protection, cycle-by-cycle current limit, VCC Over Voltage Protection (VOVP), Secondary-side Output OVP (SOVP) and UVP (SUVP), internal OTP, Over Load Protection (OLP) and pins’ fault protection. Combined with Diodes Incorporated’s synchronous controller APR347, the AP3303 system can achieve the higher power conversion efficiency and the better thermal performance.


  • Switching AC-DC Adapter/Charger
  • ATX/BTX Auxiliary Power
  • Set-Top Box (STB) Power Supply
  • Open Frame Switching Power Supply


  • Quasi-Resonant Operation under all Line and Load Condition
  • Non-Audible-Noise Quasi-Resonant Control
  • High-Voltage Startup
  • Embedded VCC LDO to Guarantee Wide Range VCC_IN Voltage
  • Low VCC Charge Current Reduces Standby Power in Output Short Situation
  • Adaptive Burst Mode Operation with Output Voltage
  • Adaptive Output Power Limit with Output Voltage
  • 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
  • VCC Maintain Mode
  • Useful Pin Fault Protection:

SENSE Pin Floating

FB/Opto-Coupler Open/Short

  • Comprehensive System Protection Feature:

Programmable External OTP

Over Load Protection (OLP)

Brown In/Out Protection

Secondary-Side OVP (SOVP) and UVP (SUVP)

  • SSOP-9 (Type CJ) is Available

Product Specifications

Product Parameters

HV Start-Up Circuit Yes
Startup Current 1 µA
UVLO Threshold on/off 15.8/6.7 V
Gate Output Current 350 mA
Oscillation Frequency 65 kHz
CTRL Pin Low Auto-recover
CTRL Pin High Auto-recover
VOVP Auto-recover
BNO Auto-recover
LOVP Auto-recover

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Orderable Part Number Buy from Distributor / Contact Sales Request Samples


Authorized Distributor Quantity Inventory Date Countries/Regions Buy Online
Digi-Key Electronics 3920 3/2/2021 Europe, Asia, North America Buy Now
Mouser Electronics Inc. 7889 3/2/2021 South America, North America, Asia, Europe, Middle East Buy Now
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