ICL7660, ICL7660A

FN3072 Rev.7.00

Page 8 of 11

Oct 5, 2010

Typical Applications

Simple Negative Voltage Converter

The majority of applications will undoubtedly utilize the ICL7660

and ICL7660A for generation of negative supply voltages. Figure

13 shows typical connections to provide a negative supply

negative (GND) for supply voltages below 3.5V.

The output characteristics of the circuit in Figure 13A can be

approximated by an ideal voltage source in series with a

resistance as shown in Figure 13B. The voltage source has a

ON resistance of the internal MOS switches (shown in Figure

ESR (equivalent series resistance) of C1 and C2. A good first

RSW, the total switch resistance, is a function of supply voltage

and temperature (See the Output Source Resistance graphs),

typically 23

will reduce the remaining terms, minimizing the output

term. Increasing the oscillator frequency will reduce the

longer enough time to fully charge the capacitors every cycle.

FIGURE 14. OUTPUT RIPPLE

FIGURE 15. PARALLELING DEVICES

FIGURE 16. CASCADING DEVICES FOR INCREASED OUTPUT VOLTAGE

A

B

0

-(V+)

V

1

2

3

4

8

7

6

5

ICL7660

V+

ICL7660A

1

2

3

4

8

7

6

5

ICL7660

ICL7660A

+

-

“n”

“1”

1

2

3

4

8

7

6

5

V+

1

2

3

4

8

7

6

5

+

-

10

F

+

-

10

F

+

-

10

F

+

-

10

F

ICL7660

ICL7660A

“n”

ICL7660

ICL7660A

“1”

1

2

1