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.