I want to use an amplifier circuit powered by a +/-15V supply (DC-DC converter IC with one or two Watts) to interface an ADC. I want to use clamping diodes to prevent the ADC input from leaving the voltage range 0 ... 3.3V. For that purpose I need an additional 3.3V rail generated by a supply that is also capable of sinking current. I already read on the internet that I cannot use LDOs (to step down from +15V to +3.3V) because they are usually not capable of sinking current. My simple question: Which supply topology can I use in order to source AND sink current? The datasheets only mention maximum values of current that shall not be exceeded, but not a hint about the direction of current flow. Can someone maybe provide further/additional information about supply topologies (ICs for board supply) and their properties so that I can read a bit about the topic?
EDIT: Most of the answers referred to voltage regulators, such as LDOs. But what about DC-DC converters? Can any of those converters sink current?