50mA, Regulated, Step-Down Charge Pump for 1.8V or 1.9V Logic

The MAX1730 regulated step-down charge pump generates up to 50mA at fixed output voltages of 1.8V or 1.9V from an input voltage in the 2.7V to 5.5V range. Specifically designed to provide high-efficiency logic supplies in applications that demand a compact design, the MAX1730 employs fractional conversion techniques to provide efficiency exceeding that of a linear regulator.

The MAX1730 operates at up to 2MHz, permitting the use of small 0.22µF flying capacitors while maintaining low 75µA quiescent supply current. Proprietary soft-start circuitry prevents excessive current from being drawn from the supply during startup, making the MAX1730 compatible with higher impedance sources such as alkaline and lithium-ion cells.

The MAX1730 is available in a space-saving 10-pin µMAX® package that is only 1.09mm high and occupies one-half the area of an 8-pin SO.

Applications

* Handheld Instruments (PDAs, Palmtops) * Low-Voltage Logic Supplies * PC Cards * PDAs * Wireless Handsets

* > 85% Peak Efficiency

* 50mA Guaranteed Output Current

* Dual-Mode 1.8V or 1.9V Output

* ±3% Output Voltage Accuracy

* Up to 2MHz Operating Frequency

* Small 0.22µF Capacitors

* No Inductor Required

* 2.7V to 5.5V Input Voltage Range

* Output Disconnects from Input in Shutdown Mode

* Small 10-Pin µMAX Package (1.09mm max height)