LM3503 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – Dual-Display Constant Current LED Driver with Analog Brightness Control

LM3503
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SNVS329D – JULY 2005 – REVISED AUGUST 2006
LM3503 Dual-Display Constant Current LED Driver with Analog Brightness Control
Check for Samples: LM3503
FEATURES
1
•2 Drives up to 4, 6, 8 or 10 White LEDs for Dual
Display Backlighting
• >80% Peak Efficiency
• Output Voltage Protection Options: 16V, 25V,
35V & 44V
• Input Under-Voltage Protection
• Internal Soft Start Eliminates Inrush Current
• 1 MHz Constant Switching Frequency
• Analog Brightness Control
• Wide Input Voltage Range: 2.5V to 5.5V
• 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 LM3503 is a white LED driver for lighting applications. For dual display backlighting applications, the
LM3503 provides a complete solution. The LM3503 contains two internal white LED current bypass FET (Field
Effect Transistor) switches. The white LED current can be adjusted with a DC voltage from a digital to analog
converter or RC filtered PWM (pulse-width-modulated) signal at the Cntrl pin.
With no external compensation, cycle-by-cycle current limit, output over-voltage protection, input under-voltage
protection, and dynamic white LED current control capability, the LM3503 offers superior performance over other
step-up white LED drivers.
Typical Application
L
22 PH
D
VSUPPLY
CIN
4.7 PF
Sw
VIN
VOUT1
Cntrl
VOUT2
LM3503-44
En1
Fb
En2
AGND PGND
Logic
Voltage
Signal
Inputs
MAIN:
2 to 5
LEDs
COUT
1 PF
SUB:
2 to 5
LEDs
R1
1
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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