LD7841High Performance Constant-Voltage Primary-Side-Regulation PWM Controller with Power Factor Correction

The LD7841 is a controller targeting for isolated and non− Isolated constant voltage LED drivers. Designed to support flyback, buck-boost topologies, its proprietary voltage mode control algorithm provides near−unity power factor and tightly regulates a constant output voltage from the primary side, thus eliminating the need for a secondary side feedback circuitry or an optocoupler.
The device is highly integrated with a minimum number of external components. A robust suite of safety protection is built in to simplify the design. This device is specifically intended for very compact space efficient designs and also provides a constant voltage regulation of the output if no load is connected to the LED driver.




  • Wide universal input range (85VAC ~ 305 VAC)
  • High Voltage Startup: Start-up time : < 0.5 sec.
  • Low standby power

    - No load power saving : < 0.2W

    - Standby power consumption: < 0.4W at 150mW output

  • Precise CV regulation in the steady state : < ± 5 %
  • CV regulation in the load transient: < ± 15%
  • Total Harmonic Current Optimization : THDi < 10%
  • High Power Factor : PF > 0.92
  • Robust Protection Features

    - Brown−In/Out Detection on HV pin

    - AC Over Voltage Protection on HV pin

    - Programmable Output OVP on FB pin

    - Cycle−by−cycle Peak Current Limit on CS pin

    - Over Load Protection

    - Secondary Diode short Protection

    - Pin Short/Open Circuit Protection on CS and FB pin

    - Winding Short Circuit Protection on FB pin

    - Output Short Circuit Protection

  • 250 mA / -700 mA Totem Pole Driving capability



  • LED Driver Power Supplies
  • Off Line Appliances Requiring Power Factor Correction