LM3559_16 Datasheet, PDF (1/50 Pages) Texas Instruments – Synchronous Boost Flash Driver

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LM3559
SNVS624B – JUNE 2011 – REVISED JUNE 2016
LM3559 Synchronous Boost Flash Driver With Dual 900-mA High-Side Current Sources
(1.8-A Total Flash Current)
1 Features
•1 Dual High-Side Current Sources Allow for
Grounded Cathode LED Operation
• Accurate and Programmable LED Current from
28.125 mA to 1.8 A
• Optimized Flash Current During Low Battery
Conditions
• Independent LED Current Source Programmability
• Four Operating Modes: Torch, Flash, Privacy
Indicate, and Message Indicator
• 4-Bit Analog-to-Digital (ADC) for V_LED Monitoring
• Battery Voltage Sensing and Current Scale-Back
• LED Sensing and Current Scale-Back
• Hardware Flash and Torch Enable
• Active-Low Hardware Reset
• Dual Synchronization Inputs for RF Power
Amplifier Pulse Events
• LED and Output Disconnect During Shutdown
• Open and Short LED Detection
• 400-kHz I²C-Compatible Interface
2 Applications
• Camera Phone LED Flash
• White LED Biasing
Simplified Schematic
3 Description
The LM3559 is a 2-MHz fixed-frequency synchronous
boost converter with two 900-mA constant current
drivers for high-current white LEDs. The dual high-
side current sources allow for grounded cathode LED
operation and can be tied together for providing flash
currents of up to 1.8 A. An adaptive regulation
method ensures the current for each LED remains in
regulation and maximizes efficiency.
The LM3559 is controlled via an I²C-compatible
interface. Features include: an internal 4-bit ADC to
monitor the LED voltage, independent LED current
control, a hardware flash enable allowing a logic input
to trigger the flash pulse, dual TX inputs which force
the flash pulse into a low-current torch mode allowing
for synchronization to RF power amplifier events or
other high-current conditions, an integrated
comparator designed to monitor an NTC thermistor
and provide an interrupt to the LED current, an input
voltage monitor to monitor low battery conditions, and
a flash current scale-back feature that actively
monitors the battery voltage and optimizes the flash
current during low battery-voltage conditions.
Additionally, an active high HWEN input provides a
hardware shutdown during system software failures.
The 2-MHz switching frequency, overvoltage
protection, and adjustable current limit allow for the
use of tiny, low-profile (1-µH or 2.2-µH) inductors and
(10-µF) ceramic capacitors. The device is available in
a ultra-small 16-pin DSBGA package (total solution
size < 26 mm²) and operates over the –40°C to
+85°C temperature range.
2.5 V to 5.5 V
SW
IN
OUT
HWEN
SCL
LM3559
LED 1
SDA
LED 2
STROBE
D2
TX1/TORCH/GPIO1 _LEDI/NTC
TX2/INT/GPIO2
GND
Optional Indicator
LED or LED
Thermal Sensing
Circuit
Flash
LEDs
D1
Copyright © 2016, Texas Instruments Incorporated
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LM3559
DSBGA (16)
1.96 mm × 1.96 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
LED Efficiency vs V_IN Dual LEDs
95.0
ILED = 450 mA
90.0
85.0
ILED = 337.5 mA
80.0
75.0
70.0
ILED=281.25 mA
65.0
60.0
55.0 ILED = 393.75 mA
50.0
45.0
40.0
2.5 3.0 3.5 4.0 4.5 5.0
Vin (V)
(Flash Brightness Codes 0x88 - 0xAA)
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.