LD7839High Performance Primary Side LED Controller With dimming function and Thermal Fold back

The LD7839 is a controller with active power factor correction. It supports high power factor across a wide range input of line voltages, and it drives the converter in the Quasi-Resonant (QR) mode to achieve the higher efficiency. By using Primary Side Regulation (PSR), the LD7839 controls the output current accurately without a shunt regulator and an opto-coupler at secondary side, reducing the external component count, the cost, and volume of the driver board. Designed to support flyback or buck boost topologies in voltage mode technical.

The LD7839 is compatible with analog dimming. The output current can be modulated by PWM duty ratio or average level of DIM pin.

The LD7839 housed in the standard SOIC10, The device is highly integrated with a minimum number of external components. A robust suite of safety protections is built in to simplify the design as LED open circuit , LED short circuit , VCC under voltage lockout (UVLO), VCC over voltage (VCC_OVP), over load, input under/ over voltage , external / internal over temperature , cycles by cycles current limitation…. ect. To ensure reliable operation at elevated temperatures, a user configurable current fold-back circuit is also provided.




  • Wide Input Voltage Range: 85~277Vac
  • Fast Start up Controller by ST pin (< 0.5Sec)
  • Primary Side Feedback Controller
  • Line Feed forward for Enhanced Accuracy
  • Tight Constant Current Regulation (+/-2%,typ.)
  • Power Factor Correction (> 0.9,typ)
  • Optimization Total Harmonic (< 10%,typ )
  • Dimming function by DIM pin
    - DC dimming input range : 0.5V~2.5V
    - PWM dimming input range : 800Hz~2KHz

  • Robust Protection Features
    - Brown−In/Out Detections by VS pin
    - AC input Over Voltage Protection by VS pin
    - Over Voltage Protection on VCC pin
    - Programmable Open LED (OVP) Protection on ZCD or SD pin
    - Cycle−by−cycle Peak Current Limit
    - 2rd Current Limited Protection (CSP)
    - Current Sense Short Circuit Protection (CSSP)
    - Output Short Circuit Protection
    - Thermal Fold-back on SD pin by External NTC
    - Internal Over Temperature Protection



  • AC-DC LED Lighting Driver