Tripler converts 5 to 15V
By Ken Yang, Maxim Integrated Products, Sunnyvale, CA -- EDN, 8/17/2000

By configuring a charge-pump voltage doubler as a tripler, you can readily
derive 15V from 5V (
Figure 1). A 15V rail is useful for powering op amps, LCD-bias circuits and other low-current applications. The connections shown configure the IC
1 voltage doubler as a tripler. The no-load output voltage of the circuit is approximately 3V
IN–2V
D, where V
D is the voltage drop across one diode. Use Schottky diodes as shown to minimize V
D and its effect on output voltage. Because the circuit's finite output impedance causes the output voltage to drop with load current (
Figure 2), a
practical limit for load current is approximately 30 mA. (DI #2570)