Sunnyvale, Calif. - Maxim Integrated Products' MAX1574 is a high-efficiency charge pump for driving up to three white LEDs. Packaged in a 3-by-3 mm TDFN and requiring only four external components for simplest implementation, it's touted as the simplest and smallest solution for cell phones and other handheld devices.
Its high current capability (up to 180 mA, set by an external resistor) suits it for use in camera strobes/flashes, movie lights, and keyboard backlight applications. The chip delivers a regulated, constant current with 0.6 percent current matching to the LEDs for uniform backlighting intensity. Utilizing adaptive 1x/2x modes and a low-dropout current regulator, it achieves up to 92 percent peak efficiency or 83 percent average efficiency over the full 1-cell lithium-ion (Li+) battery input-voltage range.
The MAX1574 features a single-wire, serial-pulse interface for dimming down to 5 percent of peak, soft-start to limit inrush current, over-voltage protection, thermal shutdown, and complete input-to-output disconnect during shutdown (0.1 microamp shutdown current). Its 1 MHz
fixed-frequency switching operation allows for tiny external components (0.22 microfarad capacitor for charge pump, 1 microfarad capacitors at input and output). The regulation scheme is optimized to ensure low EMI and low input ripple.
The MAX1574 is screened for the extended-industrial temperature range (-40 to +85°C). Prices start at $1.35
each 1000-up, FOB USA). An evaluation kit is available to speed designs.