LM3502 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – Step-Up Converter for White LED Applications

LM3502
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SNVS339A – SEPTEMBER 2005 – REVISED AUGUST 2006
LM3502 Step-Up Converter for White LED Applications
Check for Samples: LM3502
FEATURES
1
•2 Drive up to 4, 6, 8 or 10 White LEDs for Dual
Display Backlighting
• >80% Efficiency
• Output Voltage Options: 16V , 25V , 35V, and
44V
• Input Under-Voltage Protection
• Internal Soft Start Eliminating Inrush Current
• 1 MHz Constant Switching Frequency
• Wide Input Voltage: 2.5V to 5.5V
• Small External Components
• Low Profile Packages: <1 mm Height
– 10 Bump DSBGA
– 16 Pin WQFN
APPLICATIONS
• Dual Display Backlighting in Portable Devices
• Cellular Phones and PDAs
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 white LED
current bypass FET(Field Effect Transistor) switches that are ideal for controlling dual display applications. The
white LED current can be adjusted with a PWM signal directly from a microcontroller 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.
Typical Application
L
22 PH
D
VSUPPLY
CIN
4.7 PF
Sw
VIN
VOUT1
Cntrl
VOUT2
LM3502-44
En1
Fb
En2
AGND
PGND
Logic
Voltage
Signal
Inputs
MAIN:
2 to 5
LEDs
COUT
1 PF
SUB:
2 to 5
LEDs
R1
Figure 1. Blacklight Configuration with 10 White LEDs
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2005–2006, Texas Instruments Incorporated