LM2759 PRODUCT BRIEF: 1A Switched Capacitor Flash LED Driver with I2C Compatible InterfaceNovember 20, 2008
LM2759 PRODUCT BRIEF
1A Switched Capacitor Flash LED Driver with I2CCompatible Interface
General Description
LM2759 is an integrated low-noise, high-current switched ca-pacitor DC/DC converter with a regulated current source. Thedevice requires only four small ceramic capacitors making thetotal solution area less than 22 mm2 and the height less than1 mm. The LM2759 is capable of driving loads up to 1A froma single-cell Li-Ion battery. Maximum efficiency is achievedover the input voltage range by actively selecting the propergain based on the LED forward voltage and current require-ments.
The LED current can be programmed up to 1A via an I2C-compatible interface, along with eight selectable Flash Time-Out durations. One high-current Flash LED can be driveneither in a high-power Flash mode or a low-power Torchmode. The Strobe pin allows the flash to be toggled via aFlash enable signal from a camera module. The TX input pinlimits the Flash LED current to the Torch current level duringa RF PA pulse, to reduce high loads on the battery. Internalsoft-start circuitry limits the amount of inrush current duringstart-up.
LM2759 is offered in a small 12-pin thermally enhanced LLPpackage.
Notice: This document is not a full datasheet. For moreinformation regarding this product or to order samples,please contact your National Semiconductor sales officeor visit http://www.national.com/support/dir.html.
Features
■■■■■■■■■■■■■■■
Up to 1A Output CurrentSolution Area < 22 mm2No Inductor Required90% Peak Efficiency
Adaptive 1x, 1.5x and 2x Gains for Maximum EfficiencyLoad Disconnect in Shutdown
Accurate Input Current Control During Gain TransitionsFlash Time-Out
TX Input Pin Ensures Synchronization with RF PowerAmplifier Pulse
Torch, Flash, and Indicator Modes
External Flash Enable via Strobe Input PinStrobe Input Disable via I2C
Programmable Flash Pulse Duration, and Torch and FlashCurrents via I2C-Compatible Interface1MHz Constant Frequency Operation
Low Profile 12–Pin LLP (3mm x 3mm x 0.8mm)
Applications
■Camera Flash in Cellular Phones
Typical Application Circuit
30069301
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LM2759 PRODUCT BRIEF: 1A Switched Capacitor Flash LED Driver with I2C Compatible InterfaceNotes
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