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.