The MAX660 CMOS charge-pump voltage converter inverts a positive voltage in the range of 1.5V to 5.5V to the corresponding negative voltage. The MAX660 uses two low cost capacitors to provide 100 mA of output current without the cost, size, and EMI related to inductor based converters. With an operating current of only 120 A and operating efficiency greater than 90% at most loads, the MAX660 provides ideal performance for battery powered systems. The MAX660 may also be used as a positive voltage doubler. The oscillator frequency can be lowered by adding an external capacitor to the OSC pin. Also, the OSC pin may be used to drive the MAX660 with an external clock. A frequency control (FC) pin selects the oscillator frequency of 10 kHz or 80 kHz.