LM3556 Datasheet, PDF (1/5 Pages) Texas Instruments – 1.5A Synchronous Boost LED Flash Driver w/ High-Side Current Source

LM3556 PRODUCT BRIEF
May 31, 2012
1.5A Synchronous Boost LED Flash Driver w/ High-Side
Current Source
General Description
The LM3556 is a 4 MHz fixed-frequency synchronous boost
converter plus 1.5A 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 1.5A. An
adaptive regulation method ensures the current source re-
mains in regulation and maximizes efficiency.
The LM3556 is controlled via an I²C-compatible interface.
Features include: a hardware flash enable (STROBE) allow-
ing a logic input to trigger the flash pulse, a hardware Torch
enable (TORCH) for Movie Mode or Flashlight functions, 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, and an integrated
comparator designed to monitor an NTC thermistor and pro-
vide an interrupt to the LED current. With a fast 1 μs transition
from 0 mA to 46.9 mA, the Torch input pin can be used to
develop custom LED current waveforms.
The 4 MHz switching frequency, over-voltage protection and
adjustable current limit allow for the use of tiny, low-profile
inductors and (10 µF) ceramic capacitors. The device is avail-
able in a small 16-bump (1.615 mm x 1.665 mm x 0.6 mm)
micro SMD package and operates over the −40°C to +85°C
temperature range.
NOTE: This document is not a full datasheet. For more
information regarding this product or to order samples,
please contact your local Texas Instruments sales office
or visit www.ti.com.
Features
■ ^{Grounded Cathode LED Operation for Improved Thermal}
Management
■ ^{1.5A High-Side Current Source for Single LED}
■ ^{Accurate and Programmable LED Current from 46.9 mA}
to 1.5A
■ ^{> 85% Efficiency in Torch Mode (@ 100 mA) and Flash}
Mode (@1A to 1.5A)
■ ^{Small Solution Size: < 20 mm2}
■ ^{LED Thermal Sensing and Current Scale-Back}
■ ^{Soft-Start Operation for Battery Protection}
■ ^{Hardware Enable Pin}
■ ^{Hardware Torch Enable}
■ ^{Hardware Strobe Enable}
■ ^{Synchronization Input for RF Power Amplifier Pulse}
Events
■ ^{VIN Flash Monitor Optimization}
■ ^{400 kHz I2C-Compatible Interface}
■ ^{I2C-Programmable NTC Trip Point}
■ ^{0.4 mm Pitch, 16-Bump micro SMD}
Applications
■ ^{Camera Phone LED Flash}
Typical Application Circuit
© 2012 Texas Instruments Incorporated 301718 SNVS796A
30171801
www.ti.com