New Product Bulletin 4ch PWM-Dimming LED Driver BD9428 LED Driver for LCD Backlighting Features Industry-Leading Efficiency Product Outline BD9428 contributes to save the power (high efficiency technology) of LED back light for LCD TV's or monitors. 4 channels of high voltage (up to 80V), high current capability (250mA/ch) LED current drivers are integrated. By integrating these high V/I current source, customer can unify the design models for each size of LCD DIP16 Package panels. (Customer don't need to design one by one for each size of panels) ■ Supports a wide range of panel sizes with high voltage capability and large current capability ■ A high efficiency system Features VCC Integrated 4ch (250mA/ch), 80V LED driver supports a wide range of panel sizes Conventional Method Monitoring LED Supply Voltage Audible noise reduction circuit is integrated Anti inrush current by the soft start function 10V swing output can drive enternal MOSFET for DC/DC Block Diagram VIN CIN BD9428 CREG100 REG100 COUT OUT OSDET VCC CVCC VCC STB REGULATOR UVLO TSD (VCC) OVP SCP FILTER PWM COMP RT OSC FAIL REG100 10V Swing N Control Logic Control Block OVP 4 Patented DRIVER Current Sense 3 Soft Start Control SSFB RSSFB CSSFB ERR AMP 2 Coil Noise Reduction Circuit up to 80V high voltage + 1 The voltage at the cathode of each LED line is monitored to maintain a constant supply voltage at the lowest level to maximize the efficiency LED1 LED2 LED3 LED4 Current Driver PWM ISET CS Additio nal Loss Conventional Method Securing the output voltage to keep enough margin to the fluctuation of the LED's Vf MAX 250mA/ch ISET GND Open/Short Detect d rove Imp iency c i f Ef ROHM Patented Efficiency increased 10% (Estimated) LED supply voltage optimization OSDET U.S. Patent No. 7,235,954; 7,541,785; 7,944,189; 8,242,756 9th August,2013. .56F6705E-A 08.2013