CIN

COUT

VIN

VOUT

C1+

C1-

C2+ C2-

C1

C2

BAL

FET_CON

LED-

FB

SCL

SDA

STROBE

IND

VIO

LM3550

GND

4.7 PF

2.2 PF

1 PF

1 PF

ALD/TEMP

C1 = C2 = 1 PF, CIN = 4.7 PF, COUT = 2.2 PF

10 V X5R or X7R

Super-

Capacitor

2.7 V to 5.5 V

RSENSE

EOC

NTC

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Design

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.

LM3550

SNVS569C – MAY 2009 – REVISED OCTOBER 2016

LM3550 5-A Super-Capacitor Flash LED Driver

1

1 Features

1

•

Up to 5 A Flash Current

•

4 Selectable Super-Capacitor Charge Voltage

Levels (4.5 V, 5 V, 5.3 V, Optimized)

•

Adjustable Torch Current (60 mA to 200 mA)

•

Ambient Light or LED Thermal Sensing With

Current Scaleback

•

Dedicated Indicator LED Current Source

•

No Inductor Required

•

Programmable Flash Pulse Duration, and Torch

and Flash Currents via I2C-Compatible Interface

•

True Shutdown (LED Disconnect)

•

Flash Timeout Protection

•

Low Profile 20-Pin UQFN Package

(3 mm × 2.5 mm × 0.8 mm)

2 Applications

•

Digital Still Camera

•

Voltage Rail Management

•

Fire Alarm Notification

•

Emergency Strobe Lighting

•

Intruder Alert Notification

•

Barcode Scanner

•

Handheld Data Terminal

3 Description

The

LM3550

device

is

a

low-noise,

switched-

capacitor DC-DC converter designed to operate as a

current-limited and adjustable (up to 5.3 V) super-

capacitor

charger.

The

LM3550

features

user-

selectable termination voltages and provides one

adjustable constant current output (up to 200 mA)

and one NFET controller ideal for driving one or more

high-current LEDs in a high-power flash mode or a

low-power torch mode.

The LED current and flash pulse duration of the

LM3550 can be programmed via an I2C-compatible

interface. The STROBE pin allows the flash to be

toggled via a flash-enable signal from a controller or

camera module. The EOC pin sinks current when the

output voltage reaches 95% of the final value.

The ALD/TEMP input pin allows either a light sensor

to adjust the flash-current level based on the ambient

light conditions, or it allows for overtemperature

detection and protection of the LED during high-

power

operation

or

high

ambient-temperature

conditions.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

LM3550

UQFN (16)

3.00 mm × 2.50 mm

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

the end of the data sheet.

Typical Application