1 Features
1• 1.5-A LED Current Source Programmability
• Accurate and Programmable LED Current Range
from 1.954 mA to 1.5 A
• Torch Currents up to 500 mA (LM3648TT)
• Flash Timeout Values up to 1.6 Seconds
(LM3648TT)
• Optimized Flash LED Current During Low Battery
Conditions (IVFM)
• > 85% Efficiency in Torch Mode (at 100 mA) and
Flash Mode (at 1 A to 1.5 A)
• Grounded Cathode LED Operation for Improved
Thermal Management
• Small Solution Size: < 16 mm2
• Hardware Strobe Enable (STROBE)
• Synchronization Input for RF Power Amplifier
Pulse Events (TX)
• Hardware Torch Enable (TORCH/TEMP)
• Remote NTC Monitoring (TORCH/TEMP)
• 400-kHz I2C-Compatible Interface
– LM3648 (I2C Address = 0x63)

2 Applications
• Camera Phone White-LED Flash
• Digital Still Cameras
• Fire-Alarm Notification
• Emergency Strobe Lighting
• Intruder Alert Notification
• Barcode Scanners
• Handheld Data Terminals

3 Description
The LM3648 is an LED flash driver that provides a
high level of adjustability within a small solution size.
The LM3648 utilizes a 2-MHz or 4-MHz fixedfrequency
synchronous boost converter to provide
power to the 1.5-A constant current LED source. An
adaptive regulation method ensures the current
source remains in regulation and maximizes
efficiency.
Features of the LM3648 are controlled via an I2Ccompatible
interface. These features include:
hardware flash and hardware torch pins (STROBE
and TORCH/TEMP), a TX interrupt, and an NTC
thermistor monitor. The device offers 64
programmable currents in Flash and 128 levels in
Movie Mode (Torch) condition.
The 2-MHz or 4-MHz switching frequency options,
overvoltage protection (OVP), and adjustable current
limit allow for the use of tiny, low-profile inductors and
(10-μF) ceramic capacitors. The device operates over
a –40°C to +85°C ambient temperature range.