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

10V X5R or X7R

Super-

Capacitor

2.7V to 5.5V

EOC

NTC

4.2 mm

3 mm

Current Source

Super-Capacitor

Charger

LM3550

www.ti.com

SNVS569B – MAY 2009 – REVISED MAY 2013

Systems

Check for Samples: LM3550

1

FEATURES

2

•

Up to 5A Flash Current

•

Flash Time-Out Protection

•

4 Selectable Super-Capacitor Charge Voltage

•

LED Temperature Protection or Ambient Light

Levels (4.5V, 5.0V, 5.3V, Optimized)

Sensing Pin

•

Flash Optimized Charge Mode for Optimal

•

Low Profile 20-Pin UQFN Package (3.0 mm ×

Efficiency

2.5 mm × 0.8 mm)

–

33% Faster Charge Time Using Optimal

APPLICATIONS

Mode

•

Camera Phones

–

49% Less Power Dissipated in Current

Source using Optimal Charge Mode

•

Digital Still Camera

•

Fast Super-Capacitor Charger with 500 mA

•

Voltage Rail Management

Input Current Limit

DESCRIPTION

•

Adjustable Torch Current (60 mA to 200 mA)

LM3550 is a low-noise, switched-capacitor DC/DC

•

Ambient Light or LED Thermal Sensing with

converter designed to operate as a current-limited

Current Scaleback

and adjustable (up to 5.3V) super-capacitor charger.

•

End-of-Charge Output (EOC)

LM3550

features

user-selectable

super-capacitor

•

Dedicated Indicator LED Current Source

charge-termination voltages and an optimal charge-

termination

mode

that

maximizes

flash-energy

•

No Inductor Required

efficiency by accounting for flash element losses.

•

Manual Flash Enable via Strobe Pin Input

Additionally, the device provides one adjustable

•

Programmable Flash Pulse Duration, and

constant current output (up to 200 mA) and one

NFET controller ideal for driving one or more high-

Interface

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

low-power torch mode.

•

True Shutdown (LED Disconnect)

Typical Application Circuit

Figure 1.

Figure 2. Solution Size

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

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

2

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Copyright © 2009–2013, 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.