RT8567A Datasheet, PDF (1/13 Pages) Richtek Technology Corporation – 6-CH 43V Constant Current LED Driver with PWM Dimming Control

®
RT8567A
6-CH 43V Constant Current LED Driver with PWM Dimming
Control
General Description
The RT8567A 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 RT8567A has a wide input voltage range from 2.7V 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 RT8567A 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 RT8567A is also
adjustable from 500kHz to 2MHz, which allows flexibility
between efficiency and component size.
Features
z Wide Input Voltage : 2.7V to 24V
z High Output Voltage : Up to 43V
z Channel Current Programmable : 5mA to 40mA
z Channel Current Regulation with Accuracy ±3% and
Matching ±2%
z Dimming Controls : External PWM Input Up to 25kHz
z Adjustable Switching Frequency : 500kHz to 2MHz
z Built-In Soft-Start
z Protections
` LED Strings Open Detection
` Current Limit Protection
` Programmable Over Voltage Protection
` Over Temperature Protection
z 20-Lead WQFN Package
z RoHS Compliant and Halogen Free
Applications
z UMPC and Notebook Computer Backlight
z GPS, Portable DVD Backlight
Simplified Application Circuit
L1
D1
V_IN
C_IN
Chip Enable
LX
VIN
EN
OVP
RT8567A
PWM Signal
R_RT
R_ISET
PWM
RT
ISET
GND
CH1
CH2
CH3
CH4
CH5
CH6
C_OUT
V_OUT
R_OVP2
R_OVP1
: :::::
: : : : : : _{6 x 12 LEDs}
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
DS8567A-00 April 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
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