Types DC power supplies Īn AC-to-DC power supply operates on an AC input voltage and generates a DC output voltage. Power is "lost" (converted to heat) when components operate in their linear regions and, consequently, switching converters are usually more efficient than linear converters because their components spend less time in linear operating regions. In switching power converters, the input power is converted to AC or to DC pulses before processing, by components that operate predominantly in non-linear modes (e.g., transistors that spend most of their time in cutoff or saturation). Linear power converters process the input power directly, with all active power conversion components operating in their linear operating regions. Power supplies can be broadly divided into linear and switching types. These are popular in consumer electronics because of their safety the hazardous 120 or 240 volt main current is transformed down to a safer voltage before it enters the appliance body. An external power supply, AC adapter or power brick, is a power supply located in the load's AC power cord that plugs into a wall outlet a wall wart is an external supply integrated with the outlet plug itself. An integrated power supply is one that shares a common printed circuit board with its load. Rack mount power supplies are designed to be secured into standard electronic equipment racks. Open frame power supplies have only a partial mechanical enclosure, sometimes consisting of only a mounting base these are typically built into machinery or other equipment. A bench power supply is a stand-alone desktop unit used in applications such as circuit test and development. Power supplies are packaged in different ways and classified accordingly. Packaging Electronic bench power supply unit with " banana connector" output An isolated power supply has a power output that is electrically independent of its power input this is in contrast to other power supplies that share a common connection between power input and output. An adjustable regulated power supply is one that is both adjustable and regulated. Adjustable power supplies allow the output voltage or current to be programmed by mechanical controls (e.g., knobs on the power supply front panel), or by means of a control input, or both. Conversely, the output of an unregulated power supply can change significantly when its input voltage or load current changes. For example, a regulated power supply is one that maintains constant output voltage or current despite variations in load current or input voltage. Power supplies are categorized in various ways, including by functional features. General classification A rackmount, adjustable regulated DC power supply Functional Some power supplies have other types of inputs and outputs as well, for functions such as external monitoring and control. The input and output are usually hardwired circuit connections, though some power supplies employ wireless energy transfer to power their loads without wired connections. The source power may come from the electric power grid, such as an electrical outlet, energy storage devices such as batteries or fuel cells, generators or alternators, solar power converters, or another power supply. Other functions that power supplies may perform include limiting the current drawn by the load to safe levels, shutting off the current in the event of an electrical fault, power conditioning to prevent electronic noise or voltage surges on the input from reaching the load, power-factor correction, and storing energy so it can continue to power the load in the event of a temporary interruption in the source power ( uninterruptible power supply).Īll power supplies have a power input connection, which receives energy in the form of electric current from a source, and one or more power output or rail connections that deliver current to the load. Examples of the latter include power supplies found in desktop computers and consumer electronics devices. Some power supplies are separate standalone pieces of equipment, while others are built into the load appliances that they power. As a result, power supplies are sometimes referred to as electric power converters. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. A simple general-purpose desktop power supply used in electronic labs, with power output connector seen at lower-left and power input connector (not shown) located at the rearĪ power supply is an electrical device that supplies electric power to an electrical load. For other uses, see Power supply (disambiguation).
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