Date: 09/16/04

SP6661 High Frequency 200mA Charge Pump Inverter or Doubler

© Copyright 2004 Sipex Corporation

4

Optimizing Capacitor Selection

Refer to Figure 1 for the total output resistance for various capacitance values and oscillator

frequencies. The reservoir and charge pump capacitor values are equal. The capacitance values

required to maintain comparable ripple and output resistance typically diminish proportionately as the

pump frequency of the SP6661 increases.

0

2

4

6

8

10

12

14

16

18

20

110

100

1000

C1, C2 Capacitance (uF)

10KHz

20KHz

50KHz

100KHz

200KHz

500KHz

1000KHz

Figure 1. Total Output Resistance for various capacitance values and oscillator frequen-

cies.