MAXIM Integrated Products introduces the MAX1574 high-efficiency LED charge pump that requires only one transfer capacitor for simplest implementation. It is available from Arrow Electronics .
Packaged in a 3mm x 3mm TDFN, this device is the simplest and smallest solution for cell phones and other handheld devices. The charge pump drives up to three parallel white LEDs with a regulated, constant current for uniform intensity.
By utilizing adaptive 1x/2x modes and low-dropout current regulators, it achieves up to 92% peak efficiency or 83% average efficiency over the full 1-cell Lithium-ion (Li+) battery input-voltage range. It provides 0.6% current matching for uniform backlighting of color LCD displays. The MAX1574's high output current of up to 180mA allows it to be used in camera strobes/flashes, movie lights and keyboard backlight applications.
The MAX1574 features a single-wire, serial-pulse interface for dimming down to 5% of peak, soft-start to limit inrush current, overvoltage protection, thermal shutdown, and complete input-to-output disconnect during shutdown, using 0.1μA of shutdown current. The input voltage range is 2.7V to 5.5V.
The 1MHz fixed-frequency switching allows for tiny external components and the regulation scheme is optimised to ensure llow EMI and low input ripple. The MAX1574 is screened for the extended-industrial temperature range from -40°C to +85°C.