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Semtech SC4809C

High Performance Current Mode PWM Controller


TopologyFlyback Converter
Input voltage90-300 V
Switching frequency50-1100 kHz
Output 15 V / 1 A


The SC4809A/B/C is a 10 pin BICMOS primary side current mode controller for use in Isolated DC-DC and off-line switching power supplies. It is a highly integrated solution, requiring few external components. It featuresa high frequency of operation, accurately programmable maximum duty cycle, current mode control, line voltage monitoring, supply UVLO, low start-up current, and programmable soft start with user accessible reference.It operates in a fixed frequency, highly desirable for Telecom applications. Features a separate sync pin which simplifies synchronization to an external clock. Feeding the oscillator of one device to the sync of another forcesbiphase operation which reduces input ripple and filter size.

The SC4809A/B/C have different threshold and VREF to accommodate a wide variety of applications. These devices are available in the MSOP–10 lead freepackage.


  • Operation to 1MHz
  • Accurate programmable maximum duty cycle
  • Line voltage monitoring
  • External frequency synchronization
  • Bi-phase mode of operation for low ripple
  • Under 100μA start-up current
  • Accessible reference voltage
  • VDD undervoltage lockout
  • -40°C to 105°C operating temperature
  • 10 lead MSOP package. Lead free package available. Fully WEEE and RoHS compliant

Typical applications

  • Networking power supplies
  • Power over LAN applications
  • Telecom equipment and power supplies
  • Industrial power supplies
  • Isolated power supplies