LM2661MM NSC [National Semiconductor], LM2661MM Datasheet - Page 10

• Manufacturer Part Number: LM2661MM
• Description: Switched Capacitor Voltage Converter
• Manufacturer: NSC [National Semiconductor]

Other Applications
(Continued)
REGULATING V
out
It is possible to regulate the output of the LM2660/LM2661 by use of a low dropout regulator (such as LP2951). The whole con-
verter is depicted in Figure 8 . This converter can give a regulated output from −1.5V to −5.5V by choosing the proper resistor ratio:
= 1.235 V
where, V
ref
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 shut-
down by taking pin 3 high.
DS012911-27
FIGURE 8. Combining LM2660/LM2661 with LP2951 to Make a Negative Adjustable Regulator
Also, as shown in Figure 9 by operating LM2660/LM2661 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.
DS012911-28
FIGURE 9. Generating +5V from +3V Input Voltage
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