Courtaboeuf, France: Semtech has announced the SC618, a constant-current charge pump for white LEDs that offers innovative protection features for flash applications in cell phones, portable digital assistants (PDAs) and digital cameras. The SC618 is the first device in the company’s next-generation charge pump ICs designed to drive and protect high-current LEDs in flash applications. Using only a single setting resistor, the device operates either in flash mode to drive high-intensity bursts of up to 700 mA to a flash LED for short durations, or in spotlight (torch) mode to provide lower currents which can be maintained indefinitely. Spotlight mode is set to 40% of flash mode current, permitting the LED to remain on for longer periods of time with less battery draw. The SC618 delivers an innovative timeout feature designed to shut off the flash output current which, if improperly delivered, can subject the load to potential damage from these extended high current levels.
After one second, the SC618 disables the output current in order to safeguard the system against late or missing disable commands contributed from faulty software or system malfunction. This timeout function is part of a comprehensive protection feature set, including input over-voltage protection, output over-voltage protection, over-temperature protection, short circuit protection and soft start functionality. The SC618 provides a tightly regulated current level with minimum and maximum output current varying by only 8% over its full range of input voltage and temperature to deliver the stable light source needed for high-quality photos. In flash mode, the device can output 700mA for up to 350 ms or 500 mA for 500 ms with tight current regulation during the entire flash event.
Semtech Ltd France, Courtaboeuf, France. www.semtech.com