1-Cell to 3-Cell, High Power (1.5A), Low-Noise, Step-Up DC-DC Converter

The MAX1703 is a high-efficiency, low-noise, step-up DC-DC converter intended for use in battery-powered wireless applications. It uses a synchronous-rectified pulse-width-modulation (PWM) boost topology to generate a 2.5V to 5.5V output from battery inputs, such as one to three NiCd/NiMH cells or one Li-Ion cell. The device includes a 2A, 75mΩ, N-channel MOSFET switch and a 140mΩ, P-channel synchronous rectifier.

With its internal synchronous rectifier, the MAX1703 delivers up to 5% better efficiency than similar nonsynchronous converters. It also features a pulse-frequency-modulation (PFM) low-power mode to improve efficiency at light loads, and a 1µA shutdown mode.

The MAX1703 comes in a 16-pin narrow SO package and includes an uncommitted comparator that generates a power-good or low-battery-warning output. It also contains a linear gain block that can be used to build a linear regulator.

For lower-power outputs and a smaller package, refer to the MAX1700/MAX1701. For dual outputs (step-up plus linear regulator), refer to the MAX1705/MAX1706. For an on-board analog-to-digital converter, refer to the MAX848/MAX849.

The MAX1703 evaluation kit is available to speed designs.

Applications

* Digital Cordless Phones * Handheld Instruments (PDAs, Palmtops) * Palmtop Computers * PCS Phones * Personal Communicators * Two-Way Paging * Wireless Handsets

* Up to 95% Efficiency

* Up to 1.5A Output

* Fixed 5V or Adjustable Step-Up Output (2.5V to 5.5V)

* 0.7V to 5.5V Input Range

* Low-Power Mode (300µW)

* Low-Noise, Constant-Frequency Mode (300kHz)

* Synchronizable Switching Frequency (200kHz to 400kHz)

* 1µA Logic-Controlled Shutdown

* Power-Good Comparator

* Uncommitted Gain Block