National Semiconductor Introduces Industry's First High-side Dual LED Flash Driver
* Reuters is not responsible for the content in this press release.
National Semiconductor Introduces Industry's First High-side Dual LED Flash
Driver
PowerWise Synchronous Boost Converter Enables Thermally Optimized Flash System
in Portable Devices
SANTA CLARA, Calif., June 29 /PRNewswire-FirstCall/ -- National Semiconductor
Corp. (NYSE: NSM) today introduced the industry's first high-side
light-emitting diode (LED) driver that enables dual LED operation for the
camera flash function in portable, battery-powered multimedia devices. The
LM3554, a member of National's PowerWise(R) energy-efficient product family,
drives one or two high-current LEDs for flash applications in handheld devices
such as mobile phones, smartphones and portable scanners.
Traditional LED flash drivers sink current from a single high-current LED back
into the driver resulting in significant heat dissipation into the driver IC
and reduced system reliability. The LM3554's dual LED, high-side
current-drive architecture sources regulate current into two LEDs with
cathodes connected directly to the ground. This ground connection provides
more effective thermal dissipation while minimizing routing complexity and
protecting sensitive circuitry. Due to nonlinearity of LED light output
versus LED current, the dual LED architecture consumes less power for the same
light output as a single LED. In addition, monitoring pins enable detection
of other high current demands in the system, adaptively throttling the LED
current to avoid drawing excessive battery current, which can cause faults or
harm the system.
The LM3554 is offered in a 16-pin micro SMD package. A complete boost
converter solution for LED flash using National's LM3554 measures less than 23
mm squared.
Technical Features of National's LM3554 LED Driver
National's LM3554 flash LED driver is a fixed-frequency, step-up DC-DC
converter with two regulated current sources capable of driving loads up to
1.2A from a single-cell Li-Ion battery.
The LM3554 drives the LEDs in a high-power flash mode for still photography or
a low-power torch mode for video recording. To configure the driver,
designers can adjust the flash current levels and timer durations via an I2C
compatible interface. The LM3554 features built-in time-out protection to
protect the flash LEDs in case of a fault condition.
National's LM3554 features an adjustable switch current limit for the use of
small inductors with low saturation currents. The voltage mode offers a 5V
rail, which can be used for backlight LEDs and audio amplifier supplies. One
or more high-current LEDs can be driven either in a high-power flash mode or a
lower-power torch mode controlled by either an internal register or the strobe
and TX pins. A GPIO pin adds a separate hardware control resource to the
system. The hardware reset pin offers full control over the device in the
case of I2C communication failure. Additional features include internal
soft-start to eliminate large in-rush currents during start-up and fast
switching frequency, allowing for the use of small external components.
For more information on the LM3554 or to order samples or an evaluation board,
visit http://www.national.com/pf/LM/LM3554.html.
Availability and Pricing
National's LM3554 is available now and is priced at $2.32 in 1,000-unit
quantities. More information about National's LED drivers is available at
http://www.national.com/led.
About National Semiconductor
National Semiconductor is a leader in analog power management technology. Its
products include easy-to-use integrated circuits, PowerWise products that
enable more energy-efficient systems, and SolarMagic products which improve
the energy output of solar arrays. The company celebrates its 50th
anniversary this year. Headquartered in Santa Clara, Calif., National
reported sales of $1.46 billion for fiscal 2009. Additional information is
available at www.national.com.
National Semiconductor and PowerWise are registered trademarks of National
Semiconductor Corporation. All other trademarks are the property of their
respective owners.
Media Contact
Gayle Bullock
National Semiconductor
(408) 721-2033
gayle.bullock@nsc.com
Reader Information
Design Support Group
National Semiconductor
(800) 272-9959
www.national.com
SOURCE National Semiconductor Corp.
Media, Gayle Bullock, +1-408-721-2033, gayle.bullock@nsc.com, or Reader
Information, Design Support Group, 1-800-272-9959, both of National
Semiconductor
Comments (0)
This discussion is now closed. We welcome comments on our articles for a limited period after their publication.
Follow Reuters