About smps(switch mode power supply) A computer is an assembly of several essential and optional electronic parts such CD drive, motherboard, hard disk etc. . Every peripheral has its own power requirement and to serve the same regulated power supplies such as linear power supplies, ferro resonant power supplies and switched mode power supplies, are used. Switched mode power supplies are unanimously preferred as computer power supply units for their small size and high efficiency. SMPSunits dissipate less power by employing a transformer that regulates input voltage and provides constant current to the peripherals attached to the computer. The input voltage is chopped to different levels or is switched through different levels using a chopping process. This is done at very high frequency which enhances the efficiency of the circuit. A normal linear voltage supply can works at 30% efficiency, while an SMPS based power supply unit can provide 70-80% of efficiency. Also, using a high switching frequency usage makes the process quicker. An SMPS also has the features of being light-weight and economical as comparedto other power supplies. Also, the circuit topology of it can be varied depending upon the power requirements of the device to which it is attached. Introduced in 1960s with the Apple-II, SMPS are a light weight, economic and power efficient solution in regulating power supply to a computer. This insight will detail with the internal parts, their working and wiring of SMPS. Various types of SMPS architectures are popular on the basis of their power handling capacities and applications. The one used in computer is push-pull type which can handle input voltage of more than 200V. The image above shows a conventional 450W computer SMPS. From the outer casing, the SMPS fan and the power input plug can be seen. The purpose of installing a fan is to remove the heat produced by the SMPS. The outer casing is made from light weight metal casing, usually aluminum, so as to protect the internal structure. The casing is made by screwing upper and lower section and has segments cut to allow heat dissipation during the time a computer is in use. The image shows a grilled metal casing which provides better ventilation to the heat generated in the power supply unit. As the power supply unit is responsible to fulfill electrical requirements of multiple devices, an SMPS can have various types of connectors. Depending on the connections, there can be AT (Advanced Technology) and ATX (Advanced Technology extended) power supplies. The one shown in the images is an ATX one. In ATX power supplies, user can switch on and off the peripheral through software commands that are conveyed to the device by motherboard. On the other hand, in AT supplies, the user has to manually switch on and off the peripherals. Wiring in both types of power supply units is also quite different as ATX doesn’t has a -5V biasing voltage but features efficient remote sensing 3.3V voltage and a few more connector wires which have been discussed later in this insight. Various versions of ATX based connectors are also widely popular as there have been phenomenal developments in the hardware of computer system too.
Posted on: Tue, 16 Jul 2013 10:53:27 +0000
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