Power Electronics

White LED Charge Pump

Maxim Integrated Products new MAX1575 high-efficiency 1x/1.5x charge pump drives up to four white LEDs in the main display and up to two white LEDs in the sub-display. By utilizing the adaptive 1x/1.5x modes and low-dropout, active-current regulators, the MAX1575 attains up to 92% efficiency or an average of 85% over the full 1-cell Lithium (Li+) battery input-voltage range. It also achieves excellent matching for uniform backlighting of color LCD displays.

The MAX1575 features individual single-wire, serial-pulse interfaces for dimming brightness down to 5%, soft-start to limit inrush current, overvoltage protection, thermal shutdown, and complete input-to-output disconnect during shutdown (0.1-µA shutdown current). The 1-MHz fixed-frequency switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple, and the input-voltage range is 2.6 V to 5.5 V.

The MAX1575 is available in a space-saving 4-mm × 4-mm, 16-pin TQFN package, and is screened for the extended temperature range (-40°C to +85°C). An evaluation kit is available to speed designs.

For more information, visit www.maxim-ic.com.

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