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SD4938 is a current mode PWM controller with 150V MOSFET used for SMPS.

SD4938 integrates high-voltage start-up circuit. It enters burst mode at light load to reduce the system standby power dissipation; the frequency reduction function optimizes the conversion efficiency at light load; the soft startup function reduces the stress of device to avoid transformer saturation.

SD4938 features various protections, including VDD undervoltage protection, VDD overvoltage protection, lead edge blanking, over current protection, over temperature protection, etc. Meanwhile, if any protection occurs, the circuit will continue to restart automatically until the system recovers.

Main feature
  • Input voltage: 20V~150V

  • Adjustable output voltage including: 12V, 15V and 18V

  • Output current: 0.5A

  • High-voltage self-startup

  • Burst mode at light load 

  • Frequency reduction

  • Soft startup

  • VDD undervoltage protection

  • VDD overvoltage protection 

  • Leading edge blanking

  • Output overload protection

  • Over current protection 

  • Over temperature protection

Ordering Information
Product Name Package form Marking Hazardous Substance Control Packing Type Remarks
SD4938 SOP-8-225-1.27 SD4938 Halogen free Tube
SD4938TR SOP-8-225-1.27 SD4938 Halogen free Tape & Reel
Block Diagram


title Types of Size (KB) date Download the latest English version
SD4938 Datasheet PDF 249 2020-06-22 SD4938 Datasheet