Linear switching power supply

Linear power supply is the first alternating current through the transformer to reduce the voltagethrough the rectifier circuit, rectifier, DC pulse can be obtained after filtering, DC voltage with smallripple voltage. In order to achieve high precision DC voltage, must pass through the voltage stabilizing circuit voltage.

Linear power supply compared with switching power supply

The linear power supply voltage feedback circuit is operating in the linear (zoom), switching power supply is used for voltage regulator tube in saturation and cutoff region, namely the switch state.

Linear power supply is generally the output voltage sampling and then sent to the comparing with the reference voltage output voltage amplifier, the voltage amplifier as a voltage regulate transistorinput, is used to control the adjustment of the node voltage varies with the input changes, so as to adjust the output voltage, the switching power supply is adjusted by changing the tube opening and closing the time is to change the duty cycle to change the output voltage!

From its main features: on the linear power supply technology is very mature, low production cost,can achieve very high stability, low ripple, interference and noise itself is relatively small, butbecause of working in the frequency (50Hz), the volume of the transformer is large, efficiency is low(usually with work efficiency is only about 80%) overall volume is larger, more cumbersome andrequires high input voltage range; and is a high-frequency switching power supply working condition, the volume of the transformer is relatively small, relatively light, but compared with thelinear power supply to output ripple, but because of simple structure, low cost, high efficiency(efficiency of switching power supply on the market are up to 90% above) on many occasions has been replaced by the linear power supply, is the future development trend.

Silicon controlled rectifier power supply, linear power supply, switching power supply circuit simplecomparison

On the circuit structure, what is the linear power supply, switching power supply is controllable silicon, depends on the specific situation, the rational use of. The three circuit, with a large number of domestic and international, each have their own characteristics. Silicon controlled rectifier power supply, with its powerful output, so that the linear power supply and switch power supply can not be replaced. Linear power supply with its high precision, excellent performance and has been widely used. Switching power supply, power frequency transformer eliminating the cumbersome and thevolume and weight are reduced, a reduction, is also widely applied in many more stable output voltage, output current.

components of power supply

The type of each component in the switch power supply and main functions
The use of peripheral circuit of switch power supply in a wide variety of components, the performance of different, can be divided into general components, two kinds of special components.The types of common components in switching power supply and its main functions are as follows:
First, the resistor:
1 sampling resistance constitutes an output voltage sampling circuit, the voltage sent to thefeedback circuit.
2 resistance to pressure in the symmetrical DC input circuit of switching power supply are pressure,also known as the balancing resistor.
– 3 partial pressure resistance constitutes a resistor divider.
4 discharge resistance and power the electromagnetic interference (EMI) filter capacitor chargestorage release.
5 the current limiting resistor and current limiting protection, such as voltage regulator tube, optical coupler and input filter capacitor current limiting resistor.
6 current detection resistance and over current protection circuit for matching, output current limitswitch power supply.
7 – to provide a bypass current shunt resistance.
The load resistance 8 load resistance switching power supply (including the equivalent load resistance).
Minimum load resistance 9 minimum load resistance, necessary for maintaining the normal operation of the switch power supply, can be avoided due to load open circuit output voltage is too high.
10 dummy load and switching power supply performance in the test of temporary connection load(such as resistor, cement resistor).
The 11 filter – filter resistance resistance for type LC filter, RC filter, a PI type filter in.
12 bias resistor to control switching power supply side bias, or to stabilize the work point oftransistor.
13 protection resistance commonly used in RC, R, VD absorption circuit or type C clamp protectioncircuit.
14 frequency compensation resistor – such as a type RC error amplifier frequency compensationnetwork.
15 damping resistance from the resonant circuit.
Two, the capacitor:
The 1 filter capacitor input filter, output filter structure etc..
2 – also known as coupling capacitor capacitance, cut off the DC signal and its role, only to let the AC signal through.
3 the decoupling capacitor, such as the power supply decoupling capacitor, which can prevent the formation of self-excited oscillation.
The soft start circuit 4 soft start capacitance, output voltage and output current in the soft startprocess set up slowly.
5 a RC type capacitor frequency compensation network.
6 accelerate the capacitance is used to improve the switching speed of the transistor.
7 oscillation capacitance can form RC type and LC type oscillator.
The differential circuit 8 differential capacitance, obtain the sharp pulse.
9 bootstrap capacitor for power supply voltage input level upgrade, also constitute a voltage feed-forward circuit.
10 delay the capacitance and resistance of RC delay circuit.
11 – pump capacitor as energy storage capacitor polarity reversal in DC/DC converter.
Phase shifting circuit 12 phase shifting capacitor structure.
13 times of capacitors and diodes voltage doubler rectifier circuit.
14 denoising capacitor for noise filtering circuit.
15 neutralizing capacitor – eliminating self-excited oscillation amplifier.
16 interference suppression capacitors in EMI filter, filter out the string can be respectively and common mode interference.
17 safety capacitor, capacitor and capacitor containing X Y.
The 18 X capacitor to the common mode interference filter is generated by the primary winding, twowinding coupling capacitor, can provide the return path for the current interference from a sidecoupled to the two side, to prevent the current through the two side coupled to the earth.
The 19 Y capacitor to filter the grid between the series mode interference, commonly used in the EMI filter.
Three, the inductor:
1 a LC type filter, filter inductor.
The 2 energy storage inductors used in buck or boost DC/DC converter circuit.
3 Oscillation inductance – a LC type oscillator.
4 common mode inductance – also known as the common mode choke, commonly used in the EMIfilter, the inhibitory effect on the common mode interference from.
The 5 series mode inductance – also known as series mode choke, it uses the single winding structure, the serial input circuit in switching power supply.
6 frequency compensation inductor – LC type and LCR type frequency compensation network.
Four, transformer:
1 the frequency transformer of AC power transformer rectifier filter and isolation, then through toDC/DC converter (i.e. switching regulator power supply).
2 high frequency transformer, energy, pressure and isolation of high frequency power supply,suitable for power frequency transformer.

3 phase power supply

In general, the more the number of the current phase, can provide more. One is about to provide30A to 80A phase current, can provide the current 60A to 160A. Now more and more the newprocessor power consumption is large, the current demand is higher and higher, so the motherboard power supply part is also more and more pay attention to. To solve the currentproblems but also can be used to increase the amount of current road to solve, like electrical components of some famous board in the design of power supply circuit can use good quality, it will not cause the CPU working environment because of current change and instability. Of course, in general, the same brand, the power supply is less than the number should be better, after all, the more the number of phase manufacturing cost will be higher.
Design of eight phase power supply can provide more stable CPU voltage and current is more pure,the result was CPU lower voltage can be CPU to a higher frequency. It is not difficult to understand,but also has been confirmed by numerous media test and user.
For overclocking, CPU compression can improve the probability of success, to enhance the stabilityof overclocking is almost a law, which in fact is a kind of illusion, the probability of high voltage CPUcalculation error is bigger, the high-pressure extreme overclocking generally can only run SuperPi,not a long time stable operation. Therefore more attention overclocking game player is a CPU in thecase of pressure can get much, or add a little voltage under the circumstance of super high; the so-called best mostly refers to the pressure to ultra high frequency CPU to. But when the CPUconstitution, a multiphase power supply board would be easier to make it reach the purpose of low voltage high frequency
Three-phase AC power supply:
By three the same frequency, amplitude equal power AC voltage phase by 120 electrical degrees ofmutual difference is composed of the three-phase AC power supply. It is made of
Three-phase AC generator produces. Single phase alternating current used in daily life, is actually provided by a three-phase alternating current, AC power supply by single phase generator is now rarely used.
Compared with the single-phase AC three-phase alternating current has a lot of advantages, it isthe transmission and distribution of electrical energy into mechanical energy has obvious advantages in power generation. For example: making the three-phase generator, transformermanufacturing capacity is the same single-phase generator, transformer and material saving,simple structure, excellent performance, such as, the same material made by the three-phase motor, its capacity than a single phase motor 50%, in conveying the same power, a singletransmission line can save non-ferrous metals 25% the three-phase transmission lines, and thepower loss less than single phase power transmission. Because of the above advantages so thethree-phase alternating current widely used