High Efficiency White LED Driver with Integrated Schottky in SC70

LTC News for Immediate Release
For more information, tel. 408-432-1900
Doug Dickinson, Media Relations Mgr., ext. 2233
John Hamburger, Dir., Mkting Comm., ext. 2419
www.linear.com
High Efficiency White LED Driver with Integrated Schottky in SC70
MILPITAS, CA – March 1, 2006 – Linear Technology Corporation announces the LT3491, a
high efficiency, constant current white LED driver packaged in an SC70. The LT3491 features
an integrated Schottky diode on-chip, eliminating both the added cost and space required with an
external diode. A unique high-side LED current sense topology enables the LED cathode to be
connected directly to ground, creating a single wire current source. The LT3491 is designed to
drive up to six white LEDs from a single Li-Ion cell at efficiencies over 75%. It switches at
2.3MHz, allowing the use of a tiny inductor and capacitors while keeping switching noise out of
critical RF frequency bands. The combination of the LT3491’s high efficiency, low noise, and
extremely small “total solution” footprint make it ideal for handheld applications requiring up to
six white LEDs.
The LT3491 acts as a constant current source, delivering the same current to each white
LED, regardless of fluctuations in the LED’s forward voltage drop which varies with
temperature, manufacturing tolerances and age. This ensures uniform LED brightness. The
LT3491 utilizes True Color PWMTM Dimming to offer wide dimming ranges of up to 300:1.
Internal over-voltage circuitry protects the part when LEDs are disconnected.
The LT3491 is available from stock in an 8-lead SC70 package. Pricing starts at $1.25 for
1,000-piece quantities.
High Efficiency White LED Driver with Integrated Schottky in SC70
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Photo Caption: White LED Driver in SC70 with Integrated Schottky
Summary of Features: LT3491
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Drives Up to Six White LEDs from a 3V Supply
High Side Sense Allows “One Wire Current Source”
Internal Schottky Diode
One Pin Dimming and Shutdown
27V Open LED Protection
2.3MHz Switching Frequency
±5% Reference Accuracy
VIN Range: 2.5V to 12V
Requires Only 1uF Output Capacitor
Wide 300:1 True Color PWM Dimming Range
8-Lead SC70 Package
Company Background
Linear Technology Corporation, a manufacturer of high performance linear integrated circuits,
was founded in 1981, became a public company in 1986 and joined the S&P 500 index of major
public companies in 2000. Linear Technology products include high performance amplifiers,
comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery
chargers, data converters, communications interface circuits, RF signal conditioning circuits, and
many other analog functions. Applications for Linear Technology’s high performance circuits
include telecommunications, cellular telephones, networking products such as optical switches,
notebook and desktop computers, computer peripherals, video/multimedia, industrial
instrumentation, security monitoring devices, high-end consumer products such as digital
cameras and MP3 players, complex medical devices, automotive electronics, factory automation,
process control, and military and space systems. For more information, visit www.linear.com
Contact:
Doug Dickinson, Media Relations Manager
Linear Technology Corporation
1630 McCarthy Boulevard
Milpitas, CA 95035-7417
[email protected]
408-432-1900
READER SERVICE: Call toll-free 1-800-4-LINEAR (for literature only), or go to the company’s web site:
http://www.linear.com
Note: LT, LTC, and
Corp.
are registered trademarks and True Color PWM is a trademark of Linear Technology