LM3556_14 Datasheet, PDF (1/31 Pages) Texas Instruments – 1.5A Synchronous Boost LED Flash Driver w/ High-Side Current Source

LM3556
www.ti.com
SNVS796C – AUGUST 2011 – REVISED APRIL 2013
1.5A Synchronous Boost LED Flash Driver w/ High-Side Current Source
Check for Samples: LM3556
FEATURES
1
•2 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-Compatible Programmable NTC Trip Point
• 0.4 mm Pitch, 16-Bump DSBGA Package
APPLICATIONS
• Camera Phone LED Flash
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
remains in regulation and maximizes efficiency.
The LM3556 is controlled via an I²C-compatible
interface. Features include: a hardware flash enable
(STROBE) allowing 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 provide 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 available in a small 16-
bump (1.660 mm x 1.610 mm x 0.6 mm) DSBGA
package and operates over the −40°C to +85°C
temperature range.
TYPICAL APPLICATION CIRCUIT
1 PH
2.5V to 5.5V
10 PF
IN
SW _OUT
10 PF
ENABLE
STROBE
TORCH
TX
SDA
SCL
GND
LED
Flash
LED
TEMP
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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