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 F_EN pin. Additionally a low current (20mA) 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 I 2C compatible 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.