LM3519

Cin

4.7 PF

L

2.2 PH

D

Cout

1 PF

Gnd

LED_rtn

Vout

Vin

Sw

En

Vin

Vout

Vx

Logic

Voltage

Signal

Input

LM3519

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SNVS394A – AUGUST 2005 – REVISED SEPTEMBER 2005

LM3519 High Frequency Boost White LED Driver with High-Speed PWM Brightness

Control

Check for Samples: LM3519

1

FEATURES

•

Wide Input Voltage Range: 2.7V to 5.5V

•

Small Footprint SOT23-6 Package

2

•

Drives 2 to 4 LEDs at 20mA

•

Up to 30kHz PWM Dimming Control Capability

APPLICATIONS

•

>80% Peak Efficiency

•

LCD, White LED Backlighting on Mobile

•

Up to 8MHz Switching Frequency

Phones

•

Small External Components: 1µH -

•

Digital Still Cameras and PDAs

3.3µH(typ.2.2

μH) Inductor and 1µF Output

•

General Purpose LED Lighting in Handheld

Capacitor

Devices

•

True Shutdown Isolation

•

Over-Voltage Protection

DESCRIPTION

The LM3519 drives up to 4 white LEDs with constant current to provide LCD backlighting in handheld devices.

The LED current is internally set to 20mA. The series connection allows the LED current to be identical for

uniform brightness and minimizes the number of traces to the LEDs. Brightness control is achieved by applying a

PWM signal on enable with frequencies up to 30kHz.

The LM3519 features a proprietary PFM regulation architecture with switching frequencies between 2MHz to

8MHz, minimizing inductor size.

Over-voltage protection circuitry and high frequency operation permit the use of low-cost small output capacitors.

During shutdown, the output is disconnected from the input in order to avoid leakage current path through the

LEDs to ground.

The LM3519 is available in a tiny 6-pin SOT23 package.

Typical Application

Figure 1. Typical Application Circuit

1

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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2

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PRODUCTION DATA information is current as of publication date.

Copyright © 2005, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.