1 Features

1• 1.5-A High-Side Current Source for Single LED

• > 85% Efficiency in Torch Mode (at 100 mA) and

Flash Mode (at 1 A to 1.5 A)

• Accurate Programmable Flash LED Current from

93 mA to 1.5 A

• Accurate Programmable Torch LED Currents:

– 48.4 mA to 375 mA

– 24 mA to 187 mA (LT option)

• Small Solution Size: < 20 mm2

• Soft-Start Operation for Battery Protection

• Hardware Strobe Enable

• Synchronization Input for RF Power Amplifier

Pulse Events

• V IN Flash Monitor Optimization

• 400-kHz I2C-Compatible Interface

• 0.5-mm Pitch, 9-Bump DSBGA

2 Applications

Camera Phone LED Flash

3 Description

The LM3642 is a 4-MHz fixed-frequency synchronous

boost converter plus 1.5-A constant current driver for a high-current white LED. The high-side current

source allows for grounded cathode LED operation

providing Flash current up to 1.5 A. An adaptive

regulation method ensures the current source

remains in regulation and maximizes efficiency.

The LM3642 is controlled via an I2C-compatible

interface. Features include a hardware flash enable (STROBE) allowing a logic input to trigger the flash

pulse as well as a TX input which forces the flash

pulse into a low-current Torch Mode, allowing for

synchronization to RF power amplifier events or other

high-current conditions.

The 4-MHz switching frequency, overvoltage

protection and adjustable current limit settings allow

the use of tiny, low-profile inductors and (10-μF)

ceramic capacitors. The device is available in a small

9-bump DSBGA package and operates over the

−40°C to 85°C temperature range.