A device that converts other forms of energy into electrical energy is called a power supply. The generator can convert mechanical energy into electrical energy, and the dry battery can convert chemical energy into electrical energy. Generator. The battery itself is not charged, its two poles have positive and negative charges respectively, and the voltage is generated by the positive and negative charges (current is the charge under the action of voltage Oriented movement), the charge conductor already exists, and to generate current, only need to add voltage, when the two poles of the battery are connected to the conductor, the positive and negative charges are released to generate current, and when the charge is dissipated, also When the charge is exhausted, the current (pressure) disappears. Dry batteries are called power sources. A device that converts alternating current into direct current through a transformer and a rectifier is called a rectified power supply. An electronic device that can provide a signal is called a signal source. The crystal triode can amplify the signal sent from the front, and then transmit the amplified signal to the circuit behind. The transistor can also be regarded as a signal source for the following circuit. Rectified power supply and signal source are sometimes called power supply.
A power supply is a device that provides power to electronic equipment, also known as a power supply, which provides the electrical energy required by all components in the computer. The size of the power supply, whether the current and voltage are stable will directly affect the working performance and service life of the computer.
The computer power supply is a closed independent component installed in the main box. Its function is to convert the AC power into 5V, -5V, +12V, -12V, +3.3V and other stable DC power through a switching power supply transformer to supply It is used for system components such as the system version, floppy disk, hard disk drive and various adapter expansion cards in the main box. Generally speaking, if one power supply is broken, another backup power supply will replace it. Hardware availability can be enhanced by providing battery backup for nodes and disks. An HP-backed uninterruptible power supply (UPS), such as the HP PowerTrust, protects against momentary power loss. Disks should be connected to power circuits in such a way that mirror copies are connected to different power sources. The root disk and its corresponding node should be powered by the same power circuit. In particular, the cluster lock disk (used as an arbiter when reforming the cluster) should have a redundant power supply, or it can be powered from a power source other than the nodes in the cluster. Your HP representative can provide details on the power, disk, and LAN hardware layout of your cluster. Many current disk arrays and other rack-mounted systems contain multiple power inputs. They should be deployed as different power inputs on the equipment connected to separate circuit equipment with two or three power inputs. With no more than one circuit failing, the system continues to operate normally. Therefore, if all hardware in the cluster has 2 or 3 power inputs, at least three independent circuits are required to ensure that there is no single point of failure in the circuit design of the cluster.
Normal power supply/Special power supply
The special power supplies can be subdivided into: security power supply, high voltage power supply, medical power supply, military power supply, aerospace power supply, laser power supply, and other special power supplies
Features of Power IC
There are many types of power ICs, and their common features are:
(1) Low working voltage
The general working voltage is 3.0~3.6V. There are some operating voltages that are lower, such as 2.0, 2.5, 2.7V, etc.; there are also some
The working voltage is 5V, and there are a few special-purpose voltage sources of 12V or 28V.
(2) The working current is not large
It ranges from a few milliamps to several amps, but since the operating current of most embedded electronic products is less than 300mA, 30~
300mA power supply ICs account for a relatively large proportion in terms of variety and quantity.
(3) Small package size
Portable products developed in recent years all use patch devices, and power ICs are no exception, mainly including SO package, SOT-23 package, μMAX package and SC-70 with the smallest package size and the latest SMD package, etc., make the space occupied by the power supply Getting smaller and smaller.
(4) Perfect protection measures
The new power supply IC has complete protection measures, including: output overcurrent limit, overheat protection, short circuit protection and battery The reverse polarity protection makes the power supply safe and reliable, and not easy to be damaged.
(5) Low power consumption and power off function
The quiescent current of new power supply ICs is relatively small, generally tens of μA to hundreds of μA. Linear regulation of individual micropower
The quiescent current of the device is only 1.1μA. In addition, many power supply ICs have the function of turning off the control terminal of the power supply (controlled by level).
When the power is turned off, the power consumption of the IC itself is about 1μA. Because it can make a part of the circuit not work, it can greatly save power
able. For example, on a wireless communication device, the receiving circuit can be turned off in the sending state; the display can be turned off when the signal is not received.
Showing the circuit, etc.
(6) There is power supply status signal output
There are single-chip microcomputers in many portable electronic products. When the power supply is overheated or the battery voltage is low, the output voltage drops by a certain amount.
When fractional, the power supply IC has a power supply status signal output to the single-chip microcomputer to reset the single-chip microcomputer. This signal can also be used
It can be used as an indication of the power supply status (when the battery voltage is low, there will be an LED display).
(7) High precision of output voltage
The general output voltage accuracy is between ±2~4%, and the accuracy of many new power supply ICs can reach ±0.5~±1%; and
And the output voltage temperature coefficient is small, generally ±0.3 ~ ±0.5mV/℃, and some can reach ±0.1mV/℃ level.
The linear adjustment rate is generally 0.05% to 0.1%/V, and some can reach 0.01%/V; the load adjustment rate is generally 0.3 to 0.5%/mA,
Some can reach 0.01%/mA.
(8) New combined power supply IC
The boost DC/DC converter has high efficiency but large ripple and noise voltage, low dropout linear regulator has low efficiency but noise
The noise is the smallest, and the dual-output power supply IC composed of the two can better solve the problems of efficiency and noise. For example, digital
The power supply of the step-up DC/DC converter is used in the circuit part, and the LDO power supply is used in the circuit sensitive to noise. This power IC has
MAX710/711, MAX1705/1706, etc. Another example is the composition of charge pump + LDO, the output regulated charge pump power
Source IC, such as MAX868, which can output 0~-2VIN adjustable stable voltage, and can provide 30mA current; MAX1673
The regulated charge pump power supply IC outputs the same negative voltage as VIN, and the output current can reach 125mA.
A power supply that can provide a stable voltage and frequency is called an AC stable power supply. At present, the work done by most domestic manufacturers is to stabilize the AC voltage. The following is a brief description of the classification characteristics of some AC regulated power supplies in the market. Parameter adjustment (resonance) type stabilized power supply, the basic principle of voltage stabilization is LC series resonance, and the magnetic saturation stabilizer that appeared in the early days belongs to this category. Its advantages are simple structure, no many components, The reliability is quite high, the voltage regulation range is quite wide, and the anti-interference and anti-overload capabilities are strong. The disadvantages are high energy consumption, high noise, bulky and high cost. The parametric voltage stabilizer developed on the basis of the principle of magnetic saturation and the “magnetic amplifier adjustment electronic AC voltage stabilizer” (ie 614 type) popular in my country in the 1950s are AC voltage stabilizers of this type.
1）. Mechanical voltage regulation type, that is, the servo motor drives the carbon brush to move on the sliding surface of the winding of the autotransformer, changing the ratio of Vo to Vi, so as to realize the adjustment and stability of the output voltage. This kind of voltage regulator can be from hundreds of watts to several kilowatts. It is characterized by simple structure, low cost, and small output waveform distortion; however, the sliding contact of the carbon brush is easy to generate electric sparks, causing the brush to be damaged or even burned to failure; and the voltage adjustment speed is slow.
2）. Change the tap type, make the autotransformer into multiple fixed taps, and use 10 relays or thyristors (solid state relays) as switches to automatically change the tap position, thereby realizing the stability of the output voltage. The advantages of this type of voltage regulator are simple circuit, wide range of voltage regulation (130V-280V), high efficiency (≥95%), and low price. The disadvantage is that the precision of the voltage regulation is low (± 8 ~ 10%) and the working life is short. It is suitable for powering the air conditioner in the home. High-power compensation type—purification type voltage stabilizer (including precision type voltage stabilizer), which uses compensation links to stabilize the output voltage, and is easy to realize microcomputer control. Its advantages are good anti-interference performance, high precision of voltage regulation (≤±1%), fast response (40-60ms), simple circuit and reliable operation. The disadvantages are: there is low-frequency oscillation phenomenon when there are nonlinear loads such as computers and program-controlled switches; the input side current distortion is large, and the source power factor is low; the output voltage has a phase shift with respect to the input voltage. Units with high anti-interference requirements are suitable for use in cities. When the computer is powered, a voltage stabilizer about 2-3 times the total power of the computer must be used. Because of the advantages of voltage stabilization, anti-interference, fast response, moderate price, etc., it is widely used. Switching AC Stabilized Power Supply It is used in high-frequency pulse width modulation technology. The difference from general switching power supply is that its output must be an AC voltage with the same frequency and phase as the input side. Its output voltage waveforms include quasi-square wave, trapezoidal wave, sine wave, etc. The uninterruptible power supply (UPS) on the market removes the storage power supply and charger, which is a voltage regulator of a switching AC regulated power supply. Good performance, strong control function, easy to realize intelligence, it is a very promising AC regulated power supply. However, because of its complex circuit and high price, promotion is slow.
DC stabilized power supply can be divided into chemical power supply, linear stabilized power supply and switching stabilized power supply according to the habit, and they have various types:
The dry batteries, lead-acid batteries, nickel-cadmium, nickel-metal hydride, and lithium-ion batteries we usually use all belong to this category, each with its own advantages and disadvantages. With the development of science and technology, intelligent batteries have been produced; in terms of rechargeable battery materials, American researchers have discovered a kind of iodide of manganese, which can be used to manufacture cheap, compact, long-discharge time, and still maintain battery life after multiple charges. Environmentally friendly rechargeable battery with good performance.
A common characteristic of linear stabilized power supplies is that its power device adjustment tube works in the linear region, and the output is stabilized by the voltage drop between the adjustment tubes. Due to the large static loss of the adjustment tube, it is necessary to install a large radiator to dissipate heat. And since the transformer works at power frequency (50Hz), it is heavy. The advantages of this type of power supply are high stability, small ripple, high reliability, easy to make multi-channel, and output continuously adjustable finished products. The disadvantage is that it is bulky, cumbersome, and relatively inefficient. There are many kinds of this kind of stable power supply, which can be divided into regulated power supply, regulated current power supply and regulated voltage and current (bistable) power supply integrating regulated voltage and regulated current in terms of output properties. From the point of view of the output value, it can be divided into fixed-point output power supply, band switch adjustment type and potentiometer continuously adjustable type. From the output indication, it can be divided into pointer indication type and digital display type and so on.
A type of regulated power supply that is different from a linear regulated power supply is a switching DC regulated power supply. Its circuit types mainly include single-ended flyback, single-ended forward, half-bridge, push-pull and full-bridge. The fundamental difference between it and a linear power supply is that its transformer does not work at power frequency but at tens of kilohertz to several megahertz. The functional tube does not work in the saturation and cut-off region, that is, the switching state; the switching power supply is named after this. The advantages of switching power supply are small size, light weight, stable and reliable; the disadvantage is that compared with linear power supply, the ripple is larger (generally ≤ 1% VO (P-P), good ones can be more than ten mV (P-P) or less) . Its power can range from several watts to several kilowatts. The price ranges from 3 yuan to more than 100,000 yuan per watt. The following is a general classification of switching power supplies:
This type of power supply is also called primary power supply. It obtains energy from the power grid, and obtains a DC high voltage through high-voltage rectification and filtering, which is used by the DC/DC converter to obtain one or several stable DC voltages at the output end. The power ranges from several watts to several kilowatts. There are products for different occasions. There are many specifications and models of this type of product, and the primary power supply in the communication power supply (AC220 input, DC48V or 24V output) also belongs to this category according to the needs of users.
AC/DC is one type of switching power supply. This type of power supply is also called a primary power supply—AC is alternating current, and DC is direct current. After high-voltage rectification and filtering, a DC high voltage is obtained for the DC/DC converter to obtain one or several stable DC voltages at the output end. The power ranges from several There are products ranging from watts to several kilowatts, which are used in different occasions.
The power supply is also called the secondary power supply in the communication system. It is a DC input voltage provided by the primary power supply or a DC battery pack, and one or several DC voltages are obtained at the output terminal after DC/DC conversion.
③, communication power supply
The communication power supply is essentially a DC/DC converter power supply, but it generally supplies power with DC -48V or -24V, and uses a backup battery as a backup for DC power supply to convert the DC supply voltage into the working voltage of the circuit. It is divided into three types: central power supply, layered power supply and single board power supply, and the latter has the highest reliability.
④, radio power supply
The radio power input is AC220V/110V, and the output is DC13.8V. The power is determined by the power of the supplied station. There are products with several amps and hundreds of amps. In order to prevent the power failure of the AC grid from affecting the work of the radio, a battery pack is required as a backup, so this In addition to outputting a 13.8V DC voltage, the class power supply also has the function of automatic conversion for battery charging.
⑤, module power supply
With the rapid development of science and technology, the requirements for power supply reliability and capacity/volume ratio are getting higher and higher, and the modular power supply is showing its superiority more and more. It has high operating frequency, small size, high reliability, and is easy to install and combine to expand. So it is more and more widely used. At present, although there is corresponding module production in China, the failure rate is relatively high because the production process has not caught up with the international level. Although the cost of DC/DC module power supply is relatively high at present, from the perspective of the overall cost of the long application cycle of the product, especially the high maintenance cost and loss of goodwill caused by system failure, it is still cost-effective to choose this power module Cost-effective, it is also worth mentioning here is the Rogowski converter circuit, its outstanding advantages are simple circuit structure, high efficiency and output voltage, current ripple value close to zero.
⑥, special power supply
High-voltage low-current power supplies, high-current power supplies, 400Hz input AC/DC power supplies, etc. can be classified into this category and can be selected according to special needs. The price of switching power supply is generally 1USD/watt, and the price of special low-power and high-power power supply is slightly higher, up to 2USD/watt.