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.