High Performance Primary Side LED Controller with Dimming Function and Themal Fold Back
The LD7839 is a controller witch active power factor correction. It supports high power across a wide range input 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 accurately without a shunt regulator and an
optocoupler at secondary side, reducing 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 of
average level of DIM pin.
The device is higly integrated with a minimum number of external components. A robust suite of safety protections
is built in to simply 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,
cycle by cycle current limitation... etc.
To ensure reliable operation at elevated temperatures, a user configurable current fold back circuit is also provided.
The IC is available in SMD. LD7839 ?? in SOP-10 package.
FEATURES
▲ Wide input voltage range: 85VAC to 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 to 2.5V
- PWM dimming input range: 800Hz to 2kHz
▲ Robust protection features
- Brown-in/out detection 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
- 2nd 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
APPLICATIONS
▲ AC/DC LED lighting driver
Datasheet 
