DC power supplies and AC sources have very long service lives, which generally is a good thing. On the other hand, if you haven't recently bought one, you may not be aware of the latest features and benefits they offer.Increased flexibility is a major theme that has influenced today's supplies and sources in many ways. Power-rated supplies are a good example. Instead of buying a high-voltage, low-current supply as well as a high-current, low-voltage one, a single supply can be used over a wide range of current and voltage combinations within its maximum power rating. Power source emulation is another kind of flexibility that allows a standard power supply to replace a solar panel or battery. If the application calls for control system testing, it is advantageous to replace the actual power source with one that is fully programmable. In other cases, emulation can provide a more practical test environment or simply stand in for the real power source that may not be available. Test system simplification is a benefit supported by a supply's pulse and measurement capabilities. Rather than needing a separate DMM, pulse generator, and amplifier, you can get the same functionality from a modern power supply. A demand for higher power also is evident. Several new high-power supplies have been introduced, some as source measure units (SMUs) with two- or four-quadrant operation. When you are dealing with tens of kilowatts, the cost of power becomes important. Operating as electronic loads, several of these SMUs return a large portion of the current back to the AC line. And, whether single- or multiquadrant, many supplies support parallel or serial connections to further increase output I or V.Of course, all these features and benefits must be delivered within constraints. For example, a fast pulse mode of operation isn't too useful unless you can accurately measure the pulse shape. High-speed digitizers are needed to measure transients but may not be compatible with the more common requirement for high accuracy at DC. Similarly, programmability is important, but so too is ease of programming. The PMBus™ protocol is used specifically in power applications although you also will find USB, RS-485, GPIB, and LXI.
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