Linear universal cell phone LED/CAM driver features 600mA total output current & 92% efficiency

Jan 4th, 2008
Content Dam Leds En Ugc 2008 01 Linear Universal Cell Phone Led Cam Driver Features 600ma Total Output Current 92 Efficiency Leftcolumn Article Thumbnailimage File
Date Announced: 04 Jan 2008

Linear Technology has announced the LTC3207, an inductorless, low noise, high efficiency LED/CAM driver for cell phone displays and lighting.

The IC provides 12 individually configurable current sources for Main, Sub, RGB, Auxiliary or general purpose (GPO) displays/lights/outputs, plus drive capability for one high-current 400mA LED camera light. The universal current sources have digital control with independent dimming, brightness, blinking, and gradation control, programmable via a simple two-wire I2C serial interface. Camera flash (pulsed) or torch (continuous) current levels can be selected real time by the CAMHL pin or alternatively can be controlled by the I2C port.

The LTC3207's input voltage range of 2.9V to 5.5V has been optimized for single cell Li-Ion/Polymer battery applications. When driven from a Lithium battery (3.6V nominal), efficiencies reach 92%, with a quiescent current of only 500uA, maximizing battery run-time. Slew-rate limited switching reduces conducted and radiated noise (EMI).

The LTC3207's multimode charge pump features low-noise constant-frequency operation, automatically optimizing efficiency based on VIN and LED forward voltage conditions. The device powers up in 1x mode and automatically switches to boost mode (1.5x) when any enabled LED current source approaches dropout; a subsequent dropout switches the device into doubler (2x) mode. Internal circuitry prevents inrush current and excessive input noise during start-up and mode switching. In addition, the device has short circuit and thermal protection.

The LTC3207 is available from stock in the low-profile 24-lead QFN (4mm x 4mm) package. The IC requires only five small capacitors to create a tiny, complete LED power supply and current controller solution. Pricing starts at $1.95 each for 1,000-piece quantities.


Summary of Features of the LTC3207:

· Multimode 1x/1.5x/2x Charge Pump Provides up to 92% Efficiency

· Slew Limited Switching Reduces Conducted & Radiated Noise (EMI)

· Up to 600mA Total Output Current

· 12 Universal Independently Configurable 28mA Current Sources with 64-Step Linear Brightness Control

· 400mA CAM LED Current Source with 16-Step Linear Brightness Control and 2-Second High Current Safety Timer

· Independent ON/OFF, Brightness Level, Blinking and Gradation Control for Each Current Source Using 2-Wire I2C Interface

· Automatic or Manual Mode Switching

· Low Noise, Constant Frequency Operation

· Internal Soft-Start Limits Inrush Current

· Short Circuit/Thermal Protection

· 2.9V to 5.5V Input Voltage Range

· Low-Profile 4mm x 4mm x 0.75mm QFN-24 Package






Contact
UK, Ireland, South Africa and Israel: Alastair Boyd, Linear Technology (UK) Limited Tel: +44 (0)1628 477066 E-mail: aboyd@linear.com North America and General Information: Doug Dickinson, Linear Technology Corporation Tel: (408) 432 1900 ext. 2233 E-mail: ddickinson@linear.com

E-mail:uksales@linear.com

Web Site:www.linear.com

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