LM2759 1A Switched Capacitor Flash LED Driver with I
2
C Compatible Interface
June 10, 2010
LM2759
1A Switched Capacitor Flash LED Driver with I
2
C
Compatible Interface
General Description
LM2759 is an integrated low-noise, high-current switched ca-
pacitor DC/DC converter with a regulated current source. The
device requires only four small ceramic capacitors making the
total solution area less than 22 mm
2
and the height less than
1 mm. The LM2759 is capable of driving loads up to 1A from
a single-cell Li-Ion battery. Maximum efficiency is achieved
over the input voltage range by actively selecting the proper
gain based on the LED forward voltage and current require-
ments.
The LED current can be programmed up to 1A via an I
2
C-
compatible interface, along with eight selectable Flash Time-
Out durations. One high-current Flash LED can be driven
either in a high-power Flash mode or a low-power Torch
mode. The Strobe pin allows the flash to be toggled via a
Flash enable signal from a camera module. The TX input pin
limits the Flash LED current to the Torch current level during
a RF PA pulse, to reduce high loads on the battery. Internal
soft-start circuitry limits the amount of inrush current during
start-up.
LM2759 is offered in a small 12-pin thermally enhanced LLP
package.
Features
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Up to 1A Output Current
Solution Area < 22 mm
2
No Inductor Required
90% Peak Efficiency
Adaptive 1x, 1.5x and 2x Gains for Maximum Efficiency
Load Disconnect in Shutdown
Accurate Input Current Control During Gain Transitions
Flash Time-Out
TX Input Pin Ensures Synchronization with RF Power
Amplifier Pulse
Torch, Flash, and Indicator Modes
External Flash Enable via Strobe Input Pin
Strobe Input Disable via I
2
C
Programmable Flash Pulse Duration, and Torch and Flash
Currents via I
2
C-Compatible Interface
1MHz Constant Frequency Operation
Low Profile 12–Pin LLP (3mm x 3mm x 0.8mm)
Applications
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Camera Flash in Cellular Phones
Typical Application Circuit
30069322
30069301
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300693
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