Semtronics Micro Systems

Internal MOSFET

SM5718 is a high performance offline PWM Controller for low power AC/DC charger and adaptor applications. It operates in primary-side sensing and regulation mode. Consequently, TL431 and opt coupler could be eliminated.

In Constant Current(CC) control, the current and output power setting can be adjusted externally by the sense resistor Rs at CS pin. In Constant Voltage(CV) control, multi-mode operations are utilized to achieve high performance and high efficiency. In addition, good load regulation is achieved by the built-in cable drop compensation.SM5718 operates in PFM in CC mode, and it operates in PWM in CV mode with frequency reduction at light/medium load.

SM5718 provides power on soft start control and protection coverage with auto-recovery features including Cycle-by-Cycle current limiting, VDD Over-Voltage Protection(OVP), VDD clamp and Under-Voltage Lockout(UVLO).SM5718 integrates frequency shuffling technique which can help engineers to achieve excellent EMI performance.


  • 5% Constant Voltage Regulation and 5% Constant Current Regulation at Universal AC input.
  • Primary-side Sensing and Regulation Without TL431 and Opto-coupler.
  • Programmable CV and CC Regulation.
  • Adjustable Constant Current and Output Power Setting.
  • Built-in Constant Current Control with Primary Side Feedback l Built-in Adaptive Current Peak Regulation
  • Built-in Primary winding inductance Compensation
  • Programmable Cable drop Compensation
  • Power on Soft-start
  • Built-in Leading Edge Blanking (LEB)
  • Cycle-by-Cycle Current Limiting
  • VDD Under Voltage Lockout with Hysteresis(UVLO) l VDD OVP, VDD Clamp


  • Cell Phone Charger
  • Power Adaptor for PDA and Digital Camera
  • Auxiliary Power for PC, TV etc.
  • Linear Regulator/RCC Replacement
  • Open-frame SMPS

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