LM3644 Datasheet, PDF (1/41 Pages) Texas Instruments – Dual 1.5A Current Source Camera Flash LED Driver

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LM3644, LM3644TT
SNVSA52D – AUGUST 2014 – REVISED SEPTEMBER 2015
LM3644 Dual 1.5-A Current Source Camera Flash LED Driver
1 Features
•1 Dual Independent 1.5-A LED Current Source
Programmability
• Accurate and Programmable LED Current Range
from 1.4 mA to 1.5 A
• Torch Currents up to 360 mA (LM3644TT)
• Flash Timeout Values up to 1.6 seconds
(LM3644TT)
• 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
– LM3644 (I²C Address = 0x63)
2 Applications
Camera Phone White LED Flash
3 Description
The LM3644 is a dual LED flash driver that provides
a high level of adjustability within a small solution
size. The LM3644 utilizes a 2-MHz or 4-MHz fixed-
frequency synchronous boost converter to provide
power to the dual 1.5-A constant current LED
sources. The dual 128 level current sources provide
the flexibility to adjust the current ratios between
LED1 and LED2. An adaptive regulation method
ensures the current sources remain in regulation and
maximizes efficiency.
Features of the LM3644 are controlled via an I²C-
compatible 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 independently
programmable currents in each output leg to drive the
LEDs in a Flash or 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.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (MAX)
LM3644
DSBGA (12)
1.69 mm x 1.31 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
1 2H
2.5V to 5.5V
10 2F
IN
SW _OUT
LM3644
10 2F
LED1
TORCH/TEMP
STROBE
HWEN
TX
SDA
SCL
LED2
GND
Flash
LED
Flash
LED
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.