Datasheet

LM2660
SNVS135D –SEPTEMBER 1999–REVISED MAY 2013 www.ti.com
REGULATING V
out
It is possible to regulate the output of the LM2660 by use of a low dropout regulator (such as LP2951). The
whole converter is depicted in Figure 22. This converter can give a regulated output from −1.5V to −5.5V by
choosing the proper resistor ratio:
(6)
where, V
ref
= 1.235V
The error flag on pin 5 of the LP2951 goes low when the regulated output at pin 4 drops by about 5%. The
LP2951 can be shutdown by taking pin 3 high.
Figure 22. Combining LM2660 with LP2951 to Make a Negative Adjustable Regulator
Also, as shown in Figure 23 by operating LM2660 in voltage doubling mode and adding a linear regulator (such
as LP2981) at the output, we can get +5V output from an input as low as +3V.
Figure 23. Generating +5V from +3V Input Voltage
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