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Multimode white LED driver delivers 400mA

Posted: 26 Feb 2007 ?? ?Print Version ?Bookmark and Share

Keywords:white LED? LED driver? drivers? Linear Tech? Li-ion?

LTC3218 white LED driver from Linear Tech

Linear Technology Corp. has announced the LTC3218, an inductorless high-current white LED driver that delivers up to 400mA of LED current. Its multimode architecture automatically switches between 1x or 2x boost modes, monitoring the voltage across the LED current source and switching modes only when ILED dropout is detected.

Low dropout operation
The new device uses an internal high side sense resistor to regulate LED current. This enables low dropout operation and allows the device to stay in 1x mode longer, maximizing efficiency throughout the entire Li-ion/battery charging" target=_blank>polymer battery operating range, thereby increasing battery run time while minimizing noise.

The LTC3218 delivers up to 400mA pulsed current for camera flash or up to 150mA continuous current for camera torch lighting applications, featuring convenient single-resistor programming capability. An ultralow dropout current source delivers accurate current to the LED as the IC's input voltage approaches the LED forward voltage.

Soft-start circuitry
The device employs built-in soft-start circuitry, preventing excessive inrush current during start-up and enabling a 2s flash current time-out for LED protection. Its inductorless charge pump architecture, 1MHz switching frequency, low external parts count (one flying capacitor, one programming resistor, two bypass capacitors) and compact DFN package ensure a tiny footprint and cost-effective solution, suitable for video and flash applications in camera phones, digital cameras and other portable lighting applications. The LTC3218 requires only one wire to go to the LED, which is useful in flip phones, where the driver IC and LED reside on opposite sides of the hinge.

The LTC3218 is available from stock in a low profile (0.75mm), 2-by-3mm 10-lead DFN package, and is rated from -40C to 85C. Pricing starts at $1.44 each for 1,000-piece quantities.

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Related Datasheets
Part Number Description Category
? LTC3218 400mA Single Wire Camera LED Charge Pump ICs, Interface



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