LM3553 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – 1.2A Dual Flash LED Driver System with I2C Compatible

March 6, 2008
LM3553
1.2A Dual Flash LED Driver System with I²C Compatible
Interface
General Description
The LM3553 is a fixed frequency, current mode step-up DC/
DC converter with two regulated current sinks. The device is
capable of driving loads up to 1.2A from a single-cell Li-Ion
battery.
One or more high current flash LEDs can be driven in series
either in a high power Flash mode or a lower power Torch
mode controlled by either an internal register or the F_EN pin.
Additionally a low current (20mA) indicator mode and a fixed
output voltage mode are also available.
The LM3553 has 128 current levels and 16 flash safety timer
durations that are user adjustable via an I²C compatible in-
terface. Internal soft-start eliminates large inrush currents at
start-up. Over-voltage protection circuitry and 1.2MHz switch-
ing frequency allow for the use of small, low-cost output
capacitors with lower voltage ratings.
The LM3553 includes a TX pin that forces Torch mode during
a flash event allowing for synchronization between the RF
power amplifier and Flash/Torch modes. It also includes a
multi-function pin (M/F) that can serve as a GPIO and a hard-
ware RESET pin.
The LM3553 is available in National's 3mm by 3mm LLP12
package.
Features
■ ^{Accurate and Programmable LED Current up to 1.2A in}
128 Steps
■ ^{Total Solution Size < 30mm2}
■ ^{90% Peak Efficiency}
■ ^{Drives 2 LEDs in Series with 1.2A from 5V Input}
■ ^{Drives 2 LEDs in Series with 600mA from 3.0V Input}
■ ^{Drives 1 LED with 1.2A from 3.0V Input}
■ ^{Adjustable Over-Voltage Protection Allows for Single or}
Series LED Operation
■ ^{Four Operating Modes: Torch, Flash, Indicator, and}
Voltage Mode (4.98V)
■ ^{Programmable Flash Pulse Safety Timer in 16 Steps}
■ ^{TX Input Ensures Synchronization with RF Power}
Amplifier Pulse or Prevents LED from Overheating
■ ^{LED Disconnect During Shutdown}
■ ^{Flash/Imager Synchronization via F}_EN ^Pin
■ ^{Active Low Hardware Reset}
■ ^{Multi-Function Pin (RESET and GPIO)}
■ ^{Low Profile 12-pin LLP Package (SDF12A: 3mm x 3mm x}
0.8mm, 0.4mm pitch)
Applications
■ ^{Camera Phone LED Flash}
■ ^{Smartphone and PDA Flash}
■ ^{LED Backlight}
Typical Application Circuits
© 2008 National Semiconductor Corporation 201714
20171415
Solution Size
20171419
www.national.com