This type of power circuit is known as a Distributed Power Architecture (DPA) and they are commonly used in circuit power designs. The DPA is characterized by driving a single bus voltage to feed multiple POL converters. It has also brought with it the benefits of lower cost, weight, and space along with a better quality of power. In stage 1 of power conversion, an AC-DC power supply is used to convert a line voltage to a DC bus voltage of 48 V, 24 V, or 12 V. If 48 or 24 V is used to feed the circuit, the power rail is then converted to 12 V or 5 V through an isolated DC-DC converter; this is called stage 2 conversion. As a side note, if 12 V is fed directly to the circuit load as shown on the right side of the circuit pack here, the isolated conversion used in stage 2 is not required. Conversion can proceed directly to stage 3. Stage 3, the final conversion stage, is used to reduce the 12 V or 5 V bus to the various voltages required to drive the individual semiconductor loads, like an FPGA, CPU, or DSP.