DC/DC Converter drives high-current white LEDs.

Linear Technology Corp. May 31, 2005

Press Release Summary:

With input voltage of 1-3.2 V, synchronous boost dc/dc converter, Model LTC3490, delivers up to 350 mA from single or dual cell alkaline/NiMH battery. Output voltage of 2.8-4 V is fully compliant with forward voltage requirements of high-current LEDs. Housed in 3 x 3 mm DFN package, unit features 1.3 MHz switching frequency and operates at up to 90% efficiency. Onboard analog dimming capability reduces drive current proportionally to CTRL/SHDN pin voltage.

Original Press Release:

Synchronous LED Driver Delivers Up to 350mA from Single/Dual Cell Alkaline/NiMH Powered Applications

MILPITAS, CA - May 16, 2005 - Linear Technology announces the LTC3490, a synchronous boost DC/DC converter optimized for driving high current white LEDs. The LTC3490 operates at up to 90% efficiency, maximizing battery run time while its input voltage range of 1V to 3.2V enables it to deliver up to 350mA from either a single or dual cell alkaline/NiMH battery. Its output voltage range of 2.8V to 4V is fully compliant with the forward voltage requirements of high current LEDs. The LTC3490 provides constant current drive for LED applications requiring up to 1 watt of power. Its 3mm x 3mm DFN package (or SO-8) and 1.3MHz switching frequency offer a tiny solution footprint for handheld applications.

When the LTC3490's output load is disconnected, it limits the output voltage to 4.7V, providing enhanced system reliability. Onboard analog dimming capability reduces the LED drive current proportionally to the CTRL/SHDN pin voltage. A low-battery logic output signals when the battery voltage has dropped below 1V, and at 0.85V/cell, its undervoltage lockout circuit shuts down the LTC3490 for added protection. The LTC3490 offers the most compact 1 watt LED driver solution for portable lighting and rechargeable flashlight applications.

The LTC3490 is available from stock in either a 3mm X 3mm DFN or SO-8 package. Pricing starts at $2.10 each for 1,000-piece quantities.

Summary of Features: LTC3490
o 350mA Constant Current Output
o 2.8V to 4V Output Compliance
o 1- or 2-Cell NiMH or Alkaline Input
o Synchronous Rectification: Up to 90% Efficiency
o Fixed Frequency Operation: 1.3MHz
o Low Quiescent Current: <1mA
o Very Low Shutdown Current: <50ÂµA
o Open LED Output Limited to 4.7V
o VIN Range: 1V to 3.2V
o Dimming Control
o Undervoltage Lockout to Protect Batteries
o Low Profile (0.75mm) 3mm x 3mm Thermally Enhanced 8-Lead DD and SO-8 Packages

COMPANY BACKGROUND: Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators, power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequency devices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.

For more information, contact:
Doug Dickinson, Media Relations Manager
Linear Technology Corporation
1630 McCarthy Boulevard
Milpitas, CA 95035-7417
ddickinson@linear.com
408-432-1900