Other Applications (Continued)
DS100003-26
FIGURE 6. Generating −3Vin from +Vin
DS100003-27
FIGURE 7. Generating +3Vin from +Vin
REGULATING Vout
It is possible to regulate the output of the LM2662/LM2663 by use of a low dropout regulator (such as LP2986). The whole
converter is depicted in Figure 8. This converter can give a regulated output from −1.5V to −5.5V by choosing the proper resistor
ratio:
where, Vref = 1.23V
The error flag on pin 7 of the LP2986 goes low when the regulated output at pin 5 drops by about 5% below nominal. The LP2986
can be shutdown by taking pin 8 low. The less than 1 µA quiescent current in the shutdown mode is favorable for battery powered
applications.
DS100003-28
FIGURE 8. Combining LM2662/LM2663 with LP2986 to Make a Negative Adjustable Regulator
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