LM3553 Datasheet | National Semiconductor

Description The LM3553 is a fixed frequency, current mode step-up DC/ DC converter with two regulated current sinks. The device is capable of driving loads up to 1.2A from a single-cell Li-Ion battery. One or more high current flash LEDs can be driven in series either in a high power Flash mode or a lower power Torch mode controlled by either an internal register or the FEN pin. Additionally a low current (20m A) indicator mode and a fixed output voltage mode are also available. The LM3553 has 128 current levels and 16 flash safety timer durations that are user adjustable via an I2C patible interface. Internal soft-start eliminates large inrush currents at start-up. Over-voltage protection circuitry and 1.2MHz switching frequency allow for the use of small, low-cost output capacitors with lower voltage ratings. The LM3553 includes a TX pin that forces Torch mode during a flash event allowing for synchronization between the RF power amplifier and Flash/Torch modes. It also includes a multi-function pin (M/F) that can serve as a GPIO and a hardware RESET pin. The LM3553 is available in National's 3mm by 3mm LLP12 package. Features - Accurate and Programmable LED Current up to 1.2A in - - - - - - - - - - - - - - 128 Steps Total Solution Size < 30mm2 90% Peak Efficiency Drives 2 LEDs in Series with 1.2A from 5V Input Drives 2 LEDs in Series with 600m A from 3.0V Input Drives 1 LED with 1.2A from 3.0V Input Adjustable Over-Voltage Protection Allows for Single or Series LED Operation Four Operating Modes: Torch, Flash, Indicator, and Voltage Mode (4.98V) Programmable Flash Pulse Safety Timer in 16 Steps TX Input Ensures Synchronization with RF Power Amplifier Pulse or Prevents LED from Overheating LED Disconnect During Shutdown Flash/Imager Synchronization via FEN Pin Active Low Hardware Reset Multi-Function Pin (RESET and GPIO) Low Profile 12-pin LLP Package (SDF12A: 3mm x 3mm x 0.8mm, 0.4mm pitch) Applications - Camera Phone LED Flash - Smartphone and PDA Flash - LED...