Regulating V

OUT

It is possible to regulate the negative output of the LM2664

by use of a low dropout regulator (such as LP2980). The

whole converter is depicted in Figure 6. This converter can

give a regulated output from −1.8V to −5.5V by choosing the

proper resistor ratio:

V

where, V

Note that, the following conditions must be satisfied simulta-

neously for worst case design:

V

+I

V

+I

DS100031-12

FIGURE 5. Combined Voltage Doubler and Inverter

DS100031-24

FIGURE 6. Combining LM2664 with LP2980 to Make a Negative Adjustable Regulator

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