Low-Supply Current, Step-Up DC-DC Converters with True Shutdown

The MAX1795/MAX1796/MAX1797 are high-efficiency, step-up DC-DC converters intended for small portable hand-held devices. These devices feature Maxim's True Shutdown™ circuitry, which fully disconnects the output from the input in shutdown, improves efficiency, and eliminates costly external components. All three devices also feature Maxim's proprietary LX-damping circuitry for reduced EMI in noise-sensitive applications. For additional in-system flexibility, a battery monitoring comparator (LBI/LBO) remains active even when the DC-DC converter is in shutdown.

The input voltage range is +0.7V to VOUT, where VOUT can be set from +2V to +5.5V. Startup is guaranteed from +0.85V. The MAX1795/MAX1796/MAX1797 have a preset, pin-selectable 5V or 3.3V output. The output can also be adjusted to other voltages, using two external resistors. The three devices differ only in their current limits, allowing optimization of external components for different loads: the MAX1795, MAX1796, and MAX1797 have current limits of 0.25A, 0.5A, and 1A, respectively. All devices are packaged in a compact, 8-pin µMAX® package that is only 1.09mm tall and half the size of an 8-pin SO.

Applications

* PDAs and Palmtops * Portable Digital Audio Players * Portable Terminals * Wireless Handsets

* > 95% Efficiency

* True-Shutdown Circuitry

* Output Disconnects from Input in Shutdown

* No External Schottky Diode Needed

* 25µA Quiescent Supply Current

* Low-Noise Antiringing Feature

* LBI/LBO Comparator Enabled in Shutdown

* 2µA Shutdown Current

* 8-Pin µMAX Package