LM2754 Datasheet, PDF (1/11 Pages) National Semiconductor (TI) – 800mA Switched Capacitor Flash LED Driver with Time-Out Protection

September 2006
LM2754
800mA Switched Capacitor Flash LED Driver with
Time-Out Protection
General Description
The LM2754 is an integrated low noise, high current
switched capacitor DC/DC converter with four regulated cur-
rent sinks. The device is optimized for driving 1 to 4 high
power white LEDs in parallel with a maximum current of
800mA. Maximum efficiency is achieved over the input volt-
age range by actively selecting the proper gain based on the
LED forward voltage and current requirements.
Two external low power resistors set the desired current for
Torch and Flash modes. The TX pin allows the device to be
forced into Torch mode during a Flash pulse, allowing for
synchronization between the RF power amplifier pulse and
Flash/Torch modes. To protect the device and Flash LEDs,
internal Time-Out circuitry turns off the LM2754 in case of a
faulty prolonged Flash mode. Internal soft-start circuitry lim-
its the amount of inrush current during start-up.
The LM2754 is available in a small 24-pin thermally en-
hanced LLP package.
Features
n Up to 800mA Output Current
n Wide Operating Input Voltage Range: 2.8V to 5.5V
n Drives 1, 2, 3 or 4 LEDs in Parallel
n Ability to Disable One Current Sink Via the SEL Pin to
Accommodate 3-LED Flash Modules
n Time-Out Circuitry Limits Flash Duration to 1 Second
n TX Input Ensures Synchronization with RF Power
Amplifier Pulse
n Adaptive 1x, 1.5x and 2x Gains for Maximum Efficiency
n 1MHz Constant Frequency Operation
n Output Current Limit
n True Shutdown Output Disconnect
n <1µA Shutdown Current
n Internal Soft-Start Limits Inrush Current
n No Inductor Required
n Total Solution Size without LED <28mm²
n Low Profile 24-Pin LLP Package (4mm x 4mm x 0.8mm)
Applications
n Camera Flash in Mobile Phones
n Flash for Digital Cameras
n Supplies for DSP’s, Microprocessors, Memory, MP3
Players, Pagers, Other Portable Devices
Typical Application Circuit
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