OB2273B is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications.

PWM switching frequency at normal operation is internally fixed and is trimmed to tight range. At no load or light load condition, the IC operates in extended ‘burst mode’ to minimize switching loss. Lower standby power and higher conversion efficiency is thus achieved.

VDD low startup current and low operating current contribute to a reliable power on startup and low standby design with OB2273B.

OB2273B offers complete protection coverage with auto-recovery including Cycle-by-Cycle current limiting (OCP), over load protection (OLP), Brownout protection and VDD under voltage lockout (UVLO). It also provides VDD over voltage protection (OVP) with latched shut down.  Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique.

The tone energy at below 20KHZ is minimized in the design and audio noise is eliminated during operation.

OB2273B is offered in SOT23-6 package.




  • Level 5 compliance with <100mW standby power at universal AC input.

  • Power on Soft Start Reducing MOSFET Vds Stress

  • Frequency shuffling for EMI

  • Extended Burst Mode Control For Improved Efficiency and Minimum Standby Power Design

  • Audio Noise Free Operation

  • Fixed 65KHZ Switching Frequency

  • Comprehensive Protection Coverage

    • VDD Under Voltage Lockout with Hysteresis (UVLO)       

    • Cycle-by-cycle over current threshold setting for constant output power limiting over universal input voltage range

    • Overload Protection (OLP) with auto-recovery

    • Brownout Protection with auto-recovery

    • VDD Over voltage Protection(OVP) with latch shut down



      Offline AC/DC flyback converter for

  • Battery Charger

  • Power Adaptor

  • Set-Top Box Power Supplies

  • Open-frame SMPS