Charge Pumps for inverting the voltages

[praneethrajkanakam]

I read charge pumps can be used as voltage doubler but I found I can also be used as to give negative voltage

Charge pump as voltage inerter.
say converter +5 V to -5V

but this negative voltage can be obtained by inverting the terminals of the battery then why a charge pump is used for voltage inversion purpose ?

 

[crutschow]

To have both a plus and minus voltage at the same time.
Inverting the battery terminals still leaves you with one voltage.