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Cell Phone LED Multi-Display Driver Features
Digital Control & Is 92% Efficient
by Anonymous
MILPITAS, CA - September 8, 2003 - Linear Technology announces the LTC3205, an 800kHz, low noise, high efficiency step-up, step-down fractional charge pump converter. It can drive a 1-4 LED main display, 1-2 LED sub-display plus an RGB display, all in a 4 x 4mm QFN package. Each display has digital control with independent dimming and programming via a 3-wire serial interface. The device's input voltage range of 2.7V to 4.5V optimizes it for single cell
Li-Ion cellular applications. Driven from a single cell Li-Ion battery (3.6V), efficiencies reach 92% while quiescent current is only 50uA, optimizing battery run-time. The LTC3205 requires only four small capacitors and two resistors to create a tiny solution footprint, which is capable of powering the LEDs used in three separate displays.
The LTC3205 charge pump optimizes efficiency based on VIN and LED forward voltage conditions. The device powers up in step-down mode and only switches to step-up mode when any enabled LED current source begins to enter dropout. Maximum currents for the main, sub and RGB displays are set with a single resistor. LED currents are controlled with internal current sources while dimming and ONOFF control for all displays is achieved via a 3-wire serial interface. Four dimming states are available for the main and sub displays, while 16 dimming states are available through internal PWM for the Red, Green and Blue LEDs, resulting in 4096 color combinations. Internal circuitry prevents inrush current and excessive input noise during start-up and mode switching.
The LTC3205EUF is available from stock in a 24-Lead QFN (4mm x 4mm) package. Pricing starts at $2.10 each for 1,000-piece quantities.
Summary of Features: LTC3205
* Up to 92% Efficiency without Inductors
* Step-UpStep-Down Fractional Charge Pump for Optimal Efficiency
* Independent Current and Dimming Control for 1-4 Main, 1-2 Sub and RGB Displays
* LED Currents Programmed Using a 3-Wire Serial Interface
* 0.7% LED Current Matching Error
* Low Noise, Constant Frequency Operation
* 2.7V to 4.5V Input Voltage Range
* Tiny Solution Footprint, 25mm2, 0.8mm Profile
* 4 x 4mm QFN-24 Package
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
This article courtesy of http://www.alldisplaycase.com. You may freely reprint this article on your website or in your newsletter provided this courtesy notice and the author name and URL remain intact.
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