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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?
Best regards!
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?
Best Answer
You could use a source/sink regulator such as the LT1118. These types of regulators are made for termination supplies which must source and sink current. You will probably have to put an additional regulator ahead of any termination regulator you use (perhaps a 7805?), because termination regulators are unlikely to support 15V input.