SP6660DS/11

SP6660 200mA Charge Pump Inverter or Doubler

© Copyright 2000 Sipex Corporation

17

OSC

OUT

SP6660

C1

5

1

2

7

4

FC

C2

CAP+

CAP-

GND

6

8

3

LV

C4

C3

V+

D1

D2

where

Figure 27. The SP6660 Connected for Negative Voltage Conversion with Positive Supply Multiplication

Circuit for Negative Voltage Conversion

with Positive Supply Multiplication

A designer can use the circuit in Figure 27 to

provide both an inverted output voltage at V

OUT1

and a positive multiple of V

IN

at V

OUT2

(subtracting the forward biased voltages of D1

and D2). Capacitor C1 is for the charge pump

and capacitor C2 is for the reservoir function to

generate the inverted output voltage at V

Capacitor C3 is for the charge pump and capacitor

C4 is for the reservoir function to generate the

multiplied positive output voltage at V

Designers should pay special attention to the

possibility of higher source impedances at the

generated supplies due to the finite impedance

of the common charge pump driver.