ICL7660 is a charge pump voltage converter IC used to invert the input voltage. This IC can be found in instrumentation and memory circuits. If you looking for low current dual supply voltage design then this IC is the correct choice.
Low dropout regulator (LDO) is a simple and cost-effective voltage regulator to get a regulated output voltage from a higher input voltage. The special feature of an LDO is its ability to have a very low voltage drop across it when providing a regulated output voltage.