Universal High Brightness LED Driver

The SQ9912 is a PWM high-efficiency LED driver  control IC. The SQ9912 adds Open-LoopProtection (OLP) feature to SQ9911. The SQ9912  drives LED string with constant current and OLP  pin can detect the open load condition and  clamps the output voltage at certain level to  avoid damage to the output circuit. OLP pin has  internal pull-up resistor. The SQ9912 is pin-topin compatible with SQ9911 if OLP pin is left  open. SQ9912 has Soft Start to reduce input  surge current during cold start. SQ9912 also has  pseudo-random oscillator hopping function  (Spread Sprectrum) to reduce EMI emmission so  that input EMI filter cost can be reduced. Typical  oscillator hopping range is approximately 8%  around base frquency set by ROSC. SQ9912 allows efficient operation of High Brightness  (HB) LEDs from voltage sources ranging from  85VAC up to 265VAC . SQ9912A allows wide range of external MOSFET  which has lower RDSON at higher VGS.

FEATURES

● >90% Efficiency

● Universal rectified 85 to 265VAC input range

● Constant-current LED driver 

● Applications from a few mA to more than 1A  Output

● LED string from one to hundreds of diodes 

● PWM Low-Frequency Dimming via Enable pin 

● Input voltage surge ratings up to 500V 

● Power-on sequence control and Soft Start 

● Spread Spectrum to reduce EMI filter Cost 

● Open Loop Protection (OLP) 

● Internal Thermal Protection (OTP)

● 7.5V MOSFET drive – SQ9912  10V MOSFET drive – SQ9912A 

TYPICAL APPLICATIONS 

● DC/DC or AC/DC LED Driver application

● RGB Backlighting LED Driver 

● Back Lighting of Flat Panel Displays

● General purpose constant current source 

● Signage and Decorative LED Lighting

APPLICATION CIRCUIT