2.5

3.0

3.5

4.0

4.5

5.0

Vin (V)

95.0

90.0

85.0

80.0

75.0

70.0

65.0

60.0

55.0

50.0

45.0

40.0

ILED = 450 mA

ILED=281.25 mA

ILED = 337.5 mA

ILED = 393.75 mA

Copyright © 2016, Texas Instruments Incorporated

HWEN

SCL

SDA

STROBE

TX1/TORCH/GPIO1

IN

OUT

GND

LED1

LED2

LEDI/NTC

SW

TX2/INT/GPIO2

D2

LM3559

Optional Indicator

LED or LED

Thermal Sensing

Circuit

Flash

LEDs

D1

2.5 V to 5.5 V

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Folder

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM3559

SNVS624B – JUNE 2011 – REVISED JUNE 2016

LM3559 Synchronous Boost Flash Driver With Dual 900-mA High-Side Current Sources

(1.8-A Total Flash Current)

1

1 Features

1

•

Dual High-Side Current Sources Allow for

Grounded Cathode LED Operation

•

Accurate and Programmable LED Current from

28.125 mA to 1.8 A

•

Optimized Flash Current During Low Battery

Conditions

•

Independent LED Current Source Programmability

•

Four Operating Modes: Torch, Flash, Privacy

Indicate, and Message Indicator

•

•

Battery Voltage Sensing and Current Scale-Back

•

LED Sensing and Current Scale-Back

•

Hardware Flash and Torch Enable

•

Active-Low Hardware Reset

•

Dual Synchronization Inputs for RF Power

Amplifier Pulse Events

•

LED and Output Disconnect During Shutdown

•

Open and Short LED Detection

•

2 Applications

•

Camera Phone LED Flash

•

White LED Biasing

Simplified Schematic

3 Description

The LM3559 is a 2-MHz fixed-frequency synchronous

boost converter with two 900-mA constant current

drivers for high-current white LEDs. The dual high-

side current sources allow for grounded cathode LED

operation and can be tied together for providing flash

currents of up to 1.8 A. An adaptive regulation

method ensures the current for each LED remains in

regulation and maximizes efficiency.

interface. Features include: an internal 4-bit ADC to

monitor the LED voltage, independent LED current

control, a hardware flash enable allowing a logic input

to trigger the flash pulse, dual TX inputs which force

the flash pulse into a low-current torch mode allowing

for synchronization to RF power amplifier events or

other

high-current

conditions,

an

integrated

comparator designed to monitor an NTC thermistor

and provide an interrupt to the LED current, an input

voltage monitor to monitor low battery conditions, and

a flash current scale-back feature that actively

monitors the battery voltage and optimizes the flash

current

during

low

battery-voltage

conditions.

Additionally, an active high HWEN input provides a

hardware shutdown during system software failures.

The

2-MHz

switching

frequency,

overvoltage

protection, and adjustable current limit allow for the

use of tiny, low-profile (1-µH or 2.2-µH) inductors and

(10-µF) ceramic capacitors. The device is available in

a ultra-small 16-pin DSBGA package (total solution

+85°C temperature range.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

LM3559

DSBGA (16)

1.96 mm × 1.96 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

(Flash Brightness Codes 0x88 - 0xAA)