1 Features

• 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, switchedcapacitor

DC-DC converter designed to operate as a

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

charger. The LM3550 features userselectable

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 highpower

operation or high ambient-temperature

conditions.