DC/DC converter drives 20 white LEDs from a Li-Ion battery

Milpitas, CA – March 22, 2004 – Linear Technology announces the LT3466, a dual, full function, step-up DC/DC converter specifically designed to drive up to 20 white LEDs from a Li-Ion battery. Its high efficiency, current mode and fixed frequency operation ensure uniform LED brightness, low noise and maximum battery life, while on-chip Schottky diodes eliminate both the added cost and space requirements of external diodes. The LT3466 contains two independent converters capable of driving asymmetric LED strings (up to10 in series per converter) from an input voltage of 2.7V to 24V, delivering efficiencies up to 81%. Its 3 x 3mm DFN package and tiny externals provide a very compact footprint for space-constrained handheld applications.

The LT3466 switching frequency can be set between 200kHz and 2MHz via a single resistor, enabling the designer to minimize solution footprint and maximize efficiency. A constant frequency PWM architecture minimizes noise. Its 2.7V to 24V input voltage range enables it to operate in applications ranging from Li-Ion powered handheld devices to automotive backlighting. The LT3466 acts as a constant current source, delivering the same current to each white LED. This ensures uniform LED brightness regardless of fluctuations in the LED's forward voltage drop, which vary with temperature, manufacturing tolerances and age. The two independent step-up converters are capable of driving asymmetric LED strings, with independent dimming and shutdown control of each string. Additional features include internal soft-start/inrush current limiting, and open LED protection. The combination of the LT3466's high efficiency, versatility, low noise, and extremely small footprint make it ideal for variety of backlighting applications that require many white LEDs in a tiny form factor.

The LT3466 is available from stock in a low profile (0.75mm) 3mm x 3mm DFN-10 package. Pricing starts at $2.20 each for 1,000-piece quantities.

Summary of Features: LT3466
Drives Up to 20 White LEDs from a 3.6V Supply
Two Independent Step-Up Converters Capable of Driving Asymmetric LED Strings
Independent Dimming and Shutdown Control of the Two LED Strings
Integrated Schottky Diodes
Inherently Matched LED Current
High Efficiency: Up to 81%
Internal Soft-Start Eliminates Inrush Current
Open LED Protection
Fixed Frequency Operation: Programmable up to 2MHz
Wide Input Voltage Range: 2.7V to 24V
3mm x 3mm 10-Lead DFN Package

Linear Technology Corp. Tel: 1-800-4-LINEAR (800-454-6327), or website

LT3466 Data Sheet

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