High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDs

The MAX1553/MAX1554 drive white LEDs in series with a constant current to provide efficient display backlighting in cellular phones, PDAs, and other hand-held devices. The step-up converter includes an internal 40V, low RDSON, N-channel MOSFET switch for high efficiency and maximum battery life. The MAX1553 has a current limit of 480mA for driving two to six white LEDs, while the MAX1554 has a current limit of 970mA for driving up to 10 white LEDs.

A single analog/PWM Dual Mode™ input provides two simple means of brightness adjustment. A separate enable input provides on/off control. Soft-start minimizes inrush current during startup.

The MAX1553/MAX1554 are available in space-saving 8-pin TDFN 3mm x 3mm packages.

Applications

* Cell Phones * Color Display Backlight * PDA, Palmtop, and Wireless Handhelds

* Highly Integrated and Flexible Solution for Wide Range of Backlighting Applications

* Constant-Current Regulation for Even LED Illumination

* Internal 40V MOSFET Switch Capable of Driving 10 LEDs

* 2.7V to 5.5V Input Voltage Range

* Analog or PWM Control of LED Intensity

* Optimized for Low Input Ripple

* Soft-Start Minimizes Inrush Current

* High Efficiency Improves Battery Life

* Up to 88% Efficiency Driving 6 LEDs

* Up to 82% Efficiency Driving 9 LEDs (20mA, VCC = 3.6V)

* Tiny 8-Pin, 3mm x 3mm TDFN Package Saves Space

* Small, Low-Profile External Components