Diodes Incorporated
SO 8

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Primary Side Regulated Switching Mode Power Supply Controller with external OTP

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The AP3785T is a high performance AC/DC power supply controller for battery charger and adapter applications. It can meet less than 10mW standby power for “Super Star” charger criteria. The device uses Pulse Frequency Modulation (PFM) method to build discontinuous conduction mode (DCM) flyback power supplies.

The AP3785T provides accurate constant voltage (CV), constant current (CC) and outstanding dynamic performance without requiring an opto-coupler. It also eliminates the need of loop compensation circuitry while maintaining stability.

The AP3785T is equipped with both cable drop compensation function to meet various cables with different lengths and gauges and adjustable line voltage compensation function. When AP3785T is used with AP4341 or synchronous rectifier series (for example APR343 + MOSFET, APR3415, APR34330), better under-shoot performance and higher conversion efficiency can be achieved.

The AP3785T has internal over temperature protection for itself, and also provides dedicated pin for external over temperature protection.


  • Primary Side Control -- simplified circuits & Cost effctive
  • 10mW No-load Input Power -- Power Saving
  • External Adjustable Line Compensation -- for tight CC
  • External Adjustable Cable Compensation -- for tight output voltage at cable end
  • Multiple PWM/PFM Control Mode -- to Improve Audio Noise and Efficiency
  • VCS Jitter -- to Reduce System EMI
  • Valley-on -- for the Higher Efficiency and Better EMI
  • Multiple Protections: -- for safety
  • Over Voltage Protection (OVP)
  • Output Short Circuit Protection (Auto-recovery)
  • Transformer Saturation Protection (TSP)
  • External Over Temperature Protection


  • Chargers
  • Adapters
  • Mobile Phones
  • PDAs
  • MP3
  • Standby and Auxiliary Power Supplies

Product Specifications

Product Parameters

OperatingCurrent (µA) 500
StandbyPower (Max) (mW) 10
CableCompensation ADJ
Power Rating (W) 15 W
Release Date 201509

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