Current-mode PWM Controller IC SCM1733ASA

Featured Product from Mornsun America,LLC

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In order to achieve wider application range and lower price requirements, MORNSUN launched a a new current-mode PWM controller SCM1733ASA applied to small and medium-power flyback AC/DC converter with ultra-low standby consumption of ?75mW, a maximum output power of 20W, built-in high-voltage MOS and better price-performance. It features low starting current and working current to achieve reliable start-up and achieving low consumptions.

When the ACDC integrated circuit (IC) is fully loaded, the PWM switching frequency is fixed; after the load is reduced, the green mode is entered, and the switching frequency will step down; during no-load and light load, it will switch the intermittent mode to reduce consumptions. Multiple control modes also can provide soft-start control that reduce MOS stress and frequency jitter control to obtain good EMI. The frequency of intermittent mode is higher than 22KHz without audio noise. And it has a variety of self-recovery protection, such as VDD under voltage lockout (UVLO), VDD overvoltage protection (OVP), cycle-by-cycle current limit protection (OCP), overload protection (OLP), and over temperature protection (OTP).


It can be widely applicable fields such as AC / DC adapter, set-top box power supply, auxiliary power supply, open-frame switching power supply, etc.

Typical application circuit:


  • ra Low Standby Consumption(<75mW)
  • Low VDD Startup and Operating Current
  • Built-in 650V Power MOS
  • Fixed 65KHz Switching Frequency
  • Built-in Leading Edge Blanking and Slope Compensation
  • Power-on Soft Start For Reducing MOS Stress
  • EMI Frequency Jitter for Softened EMI Signature
  • Audio Noise Free Operation
  • (OCP) Cycle-by-Cycle Over Current Limiting
  • VDD Under-Voltage Lockout with Hysteresis (UVLD), Over Load Protection (OLP), Over Temperature Protection (OTP), VDD Over Voltage Protection (OVP) and output short circuit protection