LM2754 Datasheet | National Semiconductor

.. LM2754 800m A Switched Capacitor Flash LED Driver with Time-Out Protection September 2006 LM2754 800m A 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 current sinks. The device is optimized for driving 1 to 4 high power white LEDs in parallel with a maximum current of 800m A. Maximum efficiency is achieved over the input voltage 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 limits the amount of inrush current during start-up. The LM2754 is available in a small 24-pin thermally enhanced LLP package. Features n n n n n n n n n n n n n n n Up to 800m A Output Current Wide Operating Input Voltage Range: 2.8V to 5.5V Drives 1, 2, 3 or 4 LEDs in Parallel Ability to Disable One Current Sink Via the SEL Pin to Acmodate 3-LED Flash Modules Time-Out Circuitry Limits Flash Duration to 1 Second TX Input Ensures Synchronization with RF Power Amplifier Pulse Adaptive 1x, 1.5x and 2x Gains for Maximum Efficiency 1MHz Constant Frequency Operation Output Current Limit True Shutdown Output Disconnect < 1µA Shutdown Current Internal Soft-Start Limits Inrush Current No Inductor Required Total Solution Size without LED < 28mm2 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...