As shown in FIG inverted to adopt IC1MAX868 and CMPSH-3S consisting of four times the pressure of DC/DC converter power supply. IC1MAX868 which is a type inverting charge pump
regulator integrated circuit, can produce up to -2VIN output voltage, input voltage VIN range from 1.8 ~ 5.5V. IC1 through pulse frequency modulation (PFM) to regulate the output voltage, the maximum frequency of 450kHz. Very low quiescent current (30 A). Insert a charge pump by the C3, C4 and Schottky diode in its feedback loop, to form a quadruple voltage inverter power supply circuit.The power supply at VOUT -18V, can provide current 15mA, efficiency 76%, ripple 60mV. If you reduce VOUT, allows a higher current output, such as when VOUT -15V, can provide 20mA, VOUT -12V when compared to 30mA. Its stable output voltage by the feedback resistor Rl and R Ratio is determined. That VOUT -VIN (R1/R2).