Switched-Capacitor Voltage Inverters

The ultra-small MAX870/MAX871 monolithic, CMOS charge-pump inverters accept input voltages ranging from +1.4V to +5.5V. The MAX870 operates at 125kHz, and the MAX871 operates at 500kHz. Their high efficiency (90%) and low operating current (0.7mA for the MAX870) make these devices ideal for both battery-powered and board-level voltage-conversion applications.

Oscillator control circuitry and four power MOSFET switches are included on-chip. A typical MAX870/ MAX871 application is generating a -5V supply from a +5V logic supply to power analog circuitry. Both parts come in a 5-pin SOT23-5 package and can deliver 25mA with a voltage drop of 500mV.

For a similar device with logic-controlled shutdown, refer to the MAX1720/MAX1721. For applications requiring more power, the MAX860 delivers up to 50mA with a voltage drop of 600mV, in a space-saving µMAX package.

Applications

* Battery-Operated Equipment * Cell Phones * Handy-Terminals, PDAs * Local -5V Supply from 5V Logic Supply * Medical Instruments * Small LCD Panels

* 5-Pin SOT23-5 Package

* 99% Voltage Conversion Efficiency

* Invert Input Supply Voltage

* 0.7mA Quiescent Current (MAX870)

* +1.4V to +5.5V Input Voltage

* Require Only Two Capacitors

* 25mA Output Current

* Shutdown Control