LM3502 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – Step-Up Converter for White LED Applications

September 2005
LM3502
Step-Up Converter for White LED Applications
General Description
The LM3502 is a white LED driver for lighting applications.
For dual display or large single white LED string backlighting
applications, the LM3502 provides a complete solution. The
LM3502 contains two internal whitle LED current bypass
FET(Field Effect Transitor) switches that are ideal for con-
troling dual display applications. The while LED current can
be adjusted with a PWM signal directly from a microcontrol-
ler without the need of an RC filter network.
With no external compensation, cycle-by-cycle current limit,
over-voltage protection, and under-voltage protection, the
LM3502 offers superior performance over other application
specific standard product step-up white LED drivers.
Features
n Drive up to 4, 6, 8 or 10 white LEDs for Dual Display
Backlighting
n >80% efficiency
n Output Voltage Options: 16V , 25V , 35V, and 44V
n Input Under-Voltage Protection
n Internal Soft Start Eliminating Inrush Current
n 1 MHz Constant-Switching Frequency
n Wide Input Voltage: 2.5V to 5.5V
n Small External Components
n Low Profile Packages: <1 mm Height
-10 Bump MicroSMD
-16 Pin LLP
Applications
n Dual Display BackLighting in Portable Devices
n Cellular Phones and PDAs
Typical Application
20131701
FIGURE 1. Blacklight Configuration with 10 White LEDs
© 2005 National Semiconductor Corporation DS201317
www.national.com