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.