The RT8568A is a high efficiency driver for white LEDs. It is designed for LCD panels that employ an array of LEDs as the lighting source. An integrated current mode boost controller drives six strings in parallel and supports up to 12 WLEDs per string. The internal current sinks support a maximum of ±2% current mismatching for excellent brightness uniformity in each string of LEDs. To provide enough headroom for current sink operation, the boost controller monitors the minimum voltage of the feedback pins and regulates an optimized output voltage for power efficiency.

The RT8568A has a wide input voltage range from 4.2V to 24V and can provide adjustable LED current from 5mA to 40mA. The internal 250mΩ, 43V power switch with current mode control provides cycle-by-cycle over current protection. The RT8568A also integrates PWM dimming function for accurate LED current control. The input PWM dimming frequency can operate from 200Hz to 25kHz without inducing any inrush in LED current or inductor current. The switching frequency of the RT8568A is also adjustable from 500kHz to 2MHz, which allows flexibility between efficiency and component size.

The RT8568A is available in a thin WQFN-20L 4x4 package.

应用

UMPC and Notebook Computer Backlight

GPS, Portable DVD Backlight

关键特性

Wide Input Voltage : 4.2V to 24V

High Output Voltage : Up to 43V

Channel Current Programmable : 5mA to 40mA

Channel Current Regulation with Accuracy ±3% and Matching ±2%

Dimming Controls : External PWM Input Up to 25kHz

Adjustable Switching Frequency : 500kHz to 2MHz

Built-In Soft-Start

Protections

LED Strings Open Detection

Current Limit Protection

Programmable Over Voltage Protection

Over Temperature Protection

20-Lead WQFN Package

RoHS Compliant and Halogen Free