LM3520SDX Datasheet
Display Driver, Integrated White LED Driver With Organic LED Display Power Supply,
Download: LM3520SDX Datasheet 
LM3520SDX
Display Driver, Integrated White LED Driver With Organic LED Display Power Supply,
LM3520 Integrated White LED Driver with Organic LED Display Power Supply
PRELIMINARY
January 2005
LM3520
Integrated White LED Driver with Organic LED Display
Power Supply
General
Description
The Lm3520 Is A Dual Step-up Dc/dc Converter, Designed To Drive Up To 4 White Leds With A Constant
current and to power an organic LED display with a constant voltage.
A Single External Resistor Is Used To Set The Maximum Led Current. The Led Current Can Be Adjusted
By Applying A Pwm Signal To The En Pin. For Higher Efficiency The Lm3520 Operates With Pulse
Frequency Modulation (pfm) Control Scheme When The Sub-display Is Enabled. When Main Display Is
enabled, the device is operating in PWM mode.
Overvoltage Protection Circuitry And A 1mhz Switching Frequency Allow For The Use Of Small, Low Cost
external components.
Additional
Features Include A Low-side Nfet Switch That Can Turn Off The Led String With No Dc Current Path To
ground.
The LM3520 is available in a small 14-pin thermallyenchanced LLP package.
FEATURES
N Integrated Oled And White-led Driver N 80% Efficiency N Drives Up 4 Leds At 30ma/3.6v N Up To 20v
@ 50ma/3.6v For Sub-display N True Shutdown Isolation N Small External Components N 1 Mhz Switching
Frequency N 23v Overvoltage Protection N Wide Input Voltage Range: 2.7v To 5.5v N Cycle-by-cycle
Current Limit n PWM Dimming Control n Low Profile 14-Pin LLP(3mm x 4mm x 0.8mm)
Applications
N Flip-phones/clam-shell Cellular Phones N Handheld Devices N High-fashion Cellular Phones N White
LED Backlighting n Digital Cameras
Typical
Applications
Main Display with OLED Sub Display
2005 National Semiconductor Corporation DS201288
20128803
LM3520
Functional Block Diagram
FIGURE 1. Functional Block Diagram
20128802
LM3520