Principles of switching power supplies

[Botan]

The power supplies that are used in computers meets certain functions. Rectifying current: the current line home or has an alternate set of standards for general purpose transportation and food in the cities. This alternation is an oscillation that makes the current between one way and the other at a certain frequency in cycles per second or Hertzs. The standard frequency is 50-60 Hz (meaning that oscillates in one direction or the other 50 or 60 times per second). Electronic equipment need continuous power, this requires removing the oscillation (known as AC) allowing current between one-way. The source receives high voltage household current (110/220 volts) and is prepared to suppress the oscillation in the first place, improve the frequency in hertz to achieve a constant current flow with few abrupt changes, and then reduce the voltage to a voltage that is suitable for electronic components, which is the order of -12 volts to +12 volts. Input rectifier diodes, allowing current cycles in only one direction, will retain the current peaks in that direction only, eliminating the voltage curve all power is not needed. To be eliminated that part of the current cycle, the LEDs deliver a pulsed current with staccato flow. To fill these gaps, are electrolytic capacitors, which are charged during peak voltage of the diodes receive during these peaks of current and stored for release during the gaps and give continuity to the current flow.

[Recko]

The ATX type fonts do not work with direct interruption key for breaking the current flow, however, work OK with a signal coming from the motherboard. This signal is sent by the mother only when all components are verified as OK. In an ATX power shutdown does not mean it ceases to be powered. The primary stage is still working and the secondary stage supply +3.3 volts and +5 volts. The rest of the tensions are in stand-by. The motherboard, before pressing the power button or by a signal of "wake-on" via Power Management (modem or network), sends a complete firing order to function at full secondary stage to deliver all the required voltages. ATX The only sources that can completely stop operation are those with a switch on the back off so that the final and can not re-ignited with the push of the button or with signs "wake-on." It is important for the technician to know this because without protection via UPS or stabilizer, ATX sources are susceptible to electrical problems in the home network while connected to the mains.

[Aanand]

I am discussing about the protection section, located in the Primary Stage of the source, this section is constituted by a fuse and a thermistor, which is easily recognized by their green color (like a lentil). Sometimes the thermistor is replaced by a resistance of 0.2 or 0.4 ohms. In this section, the fuse protects the entire source if there is an excessive voltage from the home network and its role is cut to protect the primary stage of the source. The thermistor is an electronic component that reduces their resistance to temperature rise. Its role at this stage of the source is lower resistance allowing the entry of more amount of current in the event of overheating of the primary stage, which is the product of over-supply requirement. This decreased resistance is obviously a limit, which depend on the extent of the thermistor and the limit imposed by the fuse. In theory, with a rise of tension at home, the fuse should be cut immediately, but sometimes getting cut, it affects the rectifier diodes and sometimes electrolytic capacitors, components of the rectifier stage and input filter. The thermistor is a very resistant to damage but still may fail, burning or cutting. Often the damage is evident because the component is part directly or loses some of its cover, a situation that is checked at a glance.

[Pandya]

Within the Primary Stage of the source, power line filter section consists of a coil-capacitor whose sole function is to eliminate the "noise" in the grid. The purpose of this section is to eliminate the noise generated by the switching of the source. Without this section, the noise would flow into the domestic network creating interference that would affect the power line and AC electrical and electronic equipment plugged into it. In the primary stage of the source, input rectifier section consists of four diodes, or commonly called an integrated bridge diodes. " The four diodes are called "bridge rectifier". The function of this stage is to convert alternating current wave network is established in negative and positive phase in a purely positive, pulsating signal.

[little-Jacqueline]

The four diodes are called "bridge rectifier". The function of this stage is to convert alternating current wave network is established in negative and positive phase in a purely positive, pulsating signal.

In making the conversion, the output voltage of the diodes is 1.41 and the entry. If from the home network will receive 220 volts, the rectifier bridge output obtained approximately 310 volts. In some models of the four diode source can be replaced by a device that looks like an integrated or sometimes by students is often confused with a power transistor. It is actually a set of four diodes in a package bundled to be commonly known as "diode bridge" or "bridge rectifier". Unlike a transistor, has 4 legs to be measured sequentially grouped together as diodes. The current wave is positive and negative phase (that is why it is called alternating current). This stage converts this wave into a DC signal that will always be positive for one of the poles. This wave rectified, although it is always continuous and positive for a pole, we can see that it is highly irregular, with peaks and troughs very abrupt. Under these conditions an electronic device can not work properly. These peaks and troughs are called "curling" or "ripple".

[Daniela007]

Always at the Primary Stage of the source, the rectifier bridge output is a pair of large electrolytic capacitors that are responsible for filtering or eliminate the ripple of the signal, known as ripple. Very close to the capacitors, there are one or more resistors that are known as "Bleeders", whose function is to download the capacitors slowly off the source. This prevents deterioration regulated release of these capacitors. The idea of this section is to obtain a nearly continuous signal, exploiting the properties of the capacitors to store and deliver electricity in a regulated manner when necessary. The capacitors are commonly call "filters" and behave just like a battery-flow control that operates while the power is flowing. The capacitors are the irregular wave and at this stage, having gone through the capacitors, the section provides a much more regular wave, with fewer ups and downs. The section behaves as a "coarse filter" of current attempts to eliminate excessive irregularity between peaks and valleys to more tolerable levels for the components.

[Anirvinya]

The main function of the power transistors is to convert the signal from the large electrolytic capacitors from the previous stage in a higher frequency signal. The home network delivers a signal of about 50 hertz and that condition comes to these transistors. After all the previous treatment, we have a pulsed signal that provides a current flow choppy, with minimal peaks and valleys. A highly irregular flow. This current pulse has a frequency of 50 hertz and function of the line of transistors is to increase the frequency of the signal pulse of 50 hertz to 18,000 hertz. What is the consequence of that treatment? Simply stabilize the signal. By increasing the pulse rate, the practical effect is that the power flow is "regularized" by the increase of frequency. The effect is very similar to a bump in the pavement about how it affects the impact of the tire. Before she was puzzled by this example, consider the following:

If you have a bump or hole in the floor of a meter in length, most likely the wheel of a car is "stuck" without being able to go out and generate a brutal impact that hits the car hard. But if the gap of one meter in length was divided into small holes 5 cm each, the tire would easily fill all the gaps until the subway car and feel hardly more than a slight vibration. The power principle is the same: the 50 hertz pulse generates a signal ripple affects electronically because it sends "irregular waves" of electrical power, with peaks and deep valleys. An irregular wave pulse current is good for electronic equipment. Transistors increase the frequency and the most important consequence of this increased frequency is that not only shortens the length of time the electric waves between peaks and valleys, but the difference between maximum and minimum is also shortened.