4-String White LED Driver with Boost Regulator

The RT8575 is a high efficiency LED driver with 40V I/O support. It is designed for LCD panel that employs an array of LEDs as the lighting source. An integrated switch current mode Boost controller drives four strings in parallel and supports up to 18 pieces of LEDs per string. The internal current sinks support typical ±1% current mismatching for excellent brightness uniformity in each LED string. To provide enough headroom for the operating of current sink, Boost controller monitors the minimum voltage of feedback pins and regulates an optimized output voltage for power efficiency.

The RT8575 has a wide input voltage operating range from 4.2V to 24V and provides adjustable 50mA to 150mA LED current. The internal 150mΩ, 60V power switch with current-mode control provides cycle-by-cycle over current protection. RT8575 also integrates PWM dimming function for accurate LED current control. The input PWM dimming frequency can operate from 120Hz to 1kHz without inducing any inrush current in LEDs or inductor. The switching frequency of RT8575 is adjustable from 150kHz to 500kHz, which allows the trade-off between efficiency and component size.

The RT8575 is available in WDFN-16L 5x5 and DIP-16 (BW) packages to achieve optimized solution for PCB space.