The DC Power Supply is a rather fundamental electronic device, however there are hundreds of DC Power Supply products on the market from dozen of manufacturers. Narrowing down the best product for your application and budget can be a daunting task. This article addresses DC Power Supply differentiators, functions and the applications they are best suited for. The article’s focus is DC Power Supplies used by engineers, manufacturers, quality professionals and electronic hobbyists for the purposes of R&D, manufacturing and testing.
Power Supplies can range in price from $50 to $20,000 and the cost is often directly proportional to the amount of power the device outputs. The primary function of a power supply is to regulate output voltage and current. It takes an input power and regulates the output power as to enforce a constant voltage and current. In the case of DC Power Supplies, the input power is converted from alternating current (AC) to direct current (DC). There are two basic types of regulated DC Power Supplies: Linear and Switching.
Linear power supplies can never output a higher voltage than the input source. In theory, a linear power supply that is driven by typical 110V wall outlet could only output 110V, assuming the device were 100% efficient. Realistically, no power supply is 100% efficient because power conversion always results in energy loss, usually in the form of heat dissipation. Therefore, linear power supplies usually output voltage that is significantly less than the input.
Switching power supplies can step-up, step-down or invert the input voltage. Switching power supplies are usually larger, noisier and more expensive than their linear counterparts, however, switching power supplies are typically more efficient.
Choosing the right DC power supply for your application requires definition of some basic design specifications: voltage range, current range, number of outputs, power cleanliness (known as “ripple”) and programmability. In general, the higher the output voltage and the lower the ripple, the more expensive the DC Power Supply. Multiple outputs and programmability features will also add to the cost.