MOS tube and IGBT tube as modern electronic devices used in high frequency of new electronic devices, so in electronic circuits are often encountered is also accustomed. However, MOS tube and IGBT tube due to the shape and static parameters are similar, sometimes in the selection, judgment, use is easy to make mistakes. The reliable identification method of MOS tube and IGBT tube clears the way for selection, judgment and use! MOS  MOS tube is MOSFET, Chinese name metal oxide semiconductor insulated gate effect tube. Its characteristics, high input impedance, fast switching speed, good thermal stability, voltage control current and other characteristics.  IGBT  IGBT insulated gate bipolar fET is a combination of MOS tube and crystal triode, MOS as the input tube and crystal triode as the output tube. So the power of the transistor is very large, so the combination of the MOS tube and the advantages of the transistor.   To sum up the two kinds of transistor, is the electronic equipment using high frequency electronic components, both in appearance and extremely similar static parameters, there are some electronic products technical monopoly, sometimes they are in the circuit model is erased, so far, they in naming and no unified standard and model system to the shape and the arrangement of pin, fundamental haphazard, become the obstacle in the process of maintenance, how to distinguish and judge become a necessary means. MOS tube and IGBT tube discrimination Identification of damped NPN TYPE IGBT and N-channel enhanced MOMS tubes Damped NPN IGBT and N-channel enhanced MOMS tubes had the same gate position, the IGBT tubes had the C-pole position corresponding to the D-pole position of the MODS tube, and the IGBT tubes had the E-pole position corresponding to the S-pole position of the MODS tube, and their distinction could be determined using dynamic and static measurements. Static measurement can judge the quality of MOS tube and IGBT tube First, short-circuit the pins of the two pipes to discharge the static electricity. There is a PN connection between the D-pole and The S-pole of the MOS tube, and the forward guide pass is reverse cut off. Thus, Rgd = Rgs = Rds = infinite, and Rsd = thousands of euros. The resistance from G pole to C pole and E pole of IGBT tube should be infinite, that is, Rgc = Rge = infinity, and there is a damping diode between IGBT tube, so it has a one-way conductive reverse cut-off characteristic, that is, Rce = infinity, and Rec = thousands of euros. From here, only the resistance of the multimeter can be used to judge whether the pipe is good or bad, but can not distinguish which kind of pipe. If the measured resistance is small, the pipe is broken down; if the measured resistance is large, the pipe is open. Dynamic measurements distinguish MOS tubes from IGBT tubes Firstly, the multimeter is used to apply voltage to the gate of the pipe to establish channel for the field effect pipe. Then, the resistance values among D, S, C and E are measured. MOS tube and IGBT tube are distinguished according to the difference of resistance values. The resistance between D, S, C and E of the two pipes is measured by the resistance barrier of the multimeter. As the channel of the field effect tube has been established, Rds = Rsd≈0, and the resistance between Rce is Rce, the on-resistance of the transistor in the amplified state, and the Rec is the on-resistance of the internal damping diode, both of which are thousands of euros. Therefore, according to the measurement, the conduction degree of the two tubes is different. The resistance value between D and S of MOS tube is much smaller than that between C and E of IGBT tube. Therefore, MOS tube and IGBT tube can be distinguished.

I. Basic knowledge of electronic components Electronic components are components of electronic components and small and medium-sized equipment and instrument equipment. They are often composed of multiple parts and can be universal in the same industry. Refers to household appliances, wireless communication, instrument panel and other industrial production of some parts, such as capacitance, audion, hairspring, accessories and other sub-components collectively. Basic knowledge of electronic components, as a procurement of electronic components, not only requires flexible business ability, but also needs to master some of the hardware of electronic components. Such as the classification of electronic components, model identification, use and other professional basic knowledge, can provide better and more professional procurement advice for enterprises. So let's take a look at some of the basics of electronic components.   II、Classification of electronic components The basic parts used in the manufacture or assembly of electronic complete machines are called electronic components, which are independent individuals in electronic circuits. 1. Active components and passive components Active element refers to the element that can stimulate and amplify, oscillate, control current or energy distribution and other active functions of electrical signal or even perform data operation and processing when energy supply is obtained. Active components include various transistors, integrated circuits (IC), video tubes and displays. Passive element is opposite to active element for, it is to cannot excite magnify to electric signal, oscillate wait, the response to electric signal is passive obedient, and electric signal passes electronic element according to original basic characteristic. The most common resistors, capacitors, inductors, and so on are passive components. Active components and passive components active components correspond to active components. If an electronic component works with a power source inside it, the device is called an active device and requires a source of energy to perform its specific function. Active devices themselves consume electricity, and high-power active devices often have radiators. The counterpart of the passive element is the passive element. Resistance, capacitance and inductance components in the circuit through the signal can complete the specified function, do not need an external excitation power, so called passive devices. Passive devices consume very little power themselves or convert it into different forms of other energy. Basic knowledge of electronic components - discrete components and integrated circuits There are two main branches of the semiconductor industry: integrated circuits and discrete devices. Discrete components are relative to integrated circuits, semiconductor discrete devices, generally refers to semiconductor crystal diode, semiconductor triode for short, transistor and semiconductor special devices, is a single function, "minimum" components, no longer have other components within the functional unit. IC integrated circuit (IC integrated circuit) is an electronic component with circuit function, which combines the transistors, resistance-capacitance-sensing elements and wiring interconnections required in a class of circuits, and makes a small piece or several small pieces of semiconductor chips or medium substrates and encapsulates them as a whole. III. Identification of common electronic components 1, resistance Resistance of basic knowledge of electronic components. Resistors, commonly referred to as resistors, are the most commonly used electronic components in electronic devices. Resistance is represented in circuits by "R" and numerals. For example, R13 represents the resistance numbered 13. The main functions of resistors in circuits are shunt, current limiting, partial voltage bias, filtering (used in combination with capacitors) and impedance matching. Parameter identification: the unit of resistance is ohm (), the multiplier unit is: kilo-ohm (K), megohm (M), etc. The conversion method is: 1 megohm (m)=1000 kao (k)=1000000 ohms. There are three methods for the parameter marking of resistance, namely, the straight standard method, the color standard method and the number standard method. 1.1, number scale method is mainly used for chip patch and other small volume circuit, such as: 472 denotes 47×100 = 4.7K; So 103 is 10,000 omega (10 with three zeros in it), which is 10k omega 1.2 Color ring labeling is the most frequently used method. The first color ring represents the largest digit of the resistance value, the second color ring represents the second digit, the third color ring represents the resistance value should have several zeros, and the fourth color ring represents the error of the resistance value.     2, capacitance Basic knowledge of capacitance of electronic components. A capacitor is a component consisting of two metal films held together and separated by an insulating material. Capacitance in the circuit is generally represented by "C" plus numbers, such as C223 means the number of 223 capacitor capacitance is mainly separated by direct flow of ac. The main parameters of the capacitor are also two, nominal capacitance and allowable error. 2.1 Nominal capacitance, refers to the capacitance marked on the capacitor, the size of the capacitance capacity is the size of the energy stored in the capacitance, the resistance of capacitance to ac signal is called capacitive reactance, it is related to the frequency and capacitance of AC signal. The capacitive reactance xc=1/2 F C (f for the frequency of the AC signal and C for the capacitance). 2.2 Identification method: The identification method of capacitance is basically the same as that of resistance, and there are three kinds of identification methods: direct standard method, color standard method and number standard method. The basic unit of capacitance is expressed as a Farad (F). Other units include milliways (MF), microways (UF), nano methods (NF), and leather methods (PF). Where: 1 Farad =103 milliways =106 microways =109 nanoways =1012 picomethods. 2.3 Direct scaling method: The capacity value of the capacitor with large capacity is directly marked on the capacitor, such as 2200 uF / 10V 2.4 Numerical representation: Generally, the capacity is represented by three digits, the first two digits are significant digits, and the third digit is multiplier. For example, 102 means 10×102pf= 1000PF. 3, inductance Basic knowledge of inductance of electronic components. Inductance coils are made by winding an insulated wire around an insulated skeleton for a certain number of turns. Dc can go through the coil, dc resistance is the resistance of the wire itself, the voltage drop is very small; When the AC signal passes through the coil, the two ends of the coil will generate a self-induction electromotive force. The direction of the self-induction electromotive force is opposite to the direction of the applied voltage, which impedes the passing of ac. Therefore, the characteristic of inductance is the on-DC resistance to AC. The higher the frequency is, the greater the coil impedance will be. Inductance and capacitance can form oscillation circuit in the circuit. Inductance is often expressed as "L" plus a number in a circuit. For example, L3 represents the inductance with the number 3. Inductance generally has the straight standard method and the color standard method, the color standard method is similar to the resistance. The basic unit of inductance is: H (H). The conversion unit is: 1h= 103MH =106uh. 4. Crystal diode The main characteristic of the diode is unidirectional conductivity, that is, under the action of the forward voltage, the conduction resistance is very small; Under the action of the reverse voltage, the conduction resistance is extremely large or infinite. Crystal diodes are used to detect radio waves in radios, to convert alternating current into pulsating direct current in power conversion circuits, and to act as non-contact switches in digital circuits. Crystal diodes can be divided into: rectifier diodes (such as 1N4004), isolation diodes (such as 1N4148), Schottky diodes (such as BAT85), light-emitting diodes, voltage regulators, and so on. 4.1, identification method: identification of a diode is very simple, small power diode n pole (cathode), the diode looks mostly USES 1 kind of color ring marking out, some diodes also use special symbols to represent a p (positive) or n pole (anode), also have use symbols for "p", "n" to determine of polarity of the diode. The positive and negative poles of the LED can be identified from the length of the pin, with the long leg being positive and the short leg being negative. 4.2 Main parameters: Rated forward working current refers to the maximum forward current allowed to pass when the diode works continuously for a long time. Because the current through the pipe will make the core heat, the temperature rises, the temperature exceeds the allowable limit (silicon tube is about 140, germanium tube is about 90), it will make the core overheat and damage. The highest reverse working voltage, the reverse voltage applied at both ends of the diode reaches a certain value, the tube will be broken down, loss of unidirectional conductivity. In order to ensure the safety of use, the maximum reverse operating voltage is stipulated. Reverse current refers to the reverse current flowing through the diode under the action of specified temperature and maximum reverse voltage. The lower the reverse current, the better the performance of the one-way guide. It is worth noting that the reverse current has a close relationship with temperature. For every 10 increase in temperature, the reverse current doubles.

MOS tube conduction characteristics 1. Conduction means as a switch, which is equivalent to switch closure. 2. NMOS features: when the Vgs exceed a certain value, it will be on. It is suitable for the condition of the source electrode grounding device (middle and low drive), if the gate voltage is 4V or 10V. 3, PMOS characteristics, Vgs lower than a certain value will be conductive, suitable for the source pole Vcc condition (high-grade drive). However, although PMOS can be easily used as a high-end driver, NMOS is generally used in high-end drivers because of the large conduction resistor, high price, and less replacement type.   MOS switch tube damage 1. Conduction loss refers to the output power loss caused by the rectifier tube from cut-off to conduction. Whether it is NMOS or PMOS, there are conduction resistors after conduction, in which case the point current will waste kinetic energy on the resistor, which is called conduction loss. Choosing MOS transistors with small conduction resistors will reduce conduction loss. Nowadays, MOS transistors with small output power are generally around tens of millivolts. 2. In the case of conduction and cut-off, MOS must not be carried out in a flash. The voltage on both sides of MOS has a whole process of decreasing, and the current passing through has a whole process of increasing. During this period, the voltage and current of MOS tube damage are multiplied, which is called switch damage. Generally, switch damage is much larger than conduction damage, and the faster the switching frequency is, the greater the damage will be. 3. The multiplication of voltage and current flow at the moment of conduction is very large, resulting in very large damage. Reduce the switching time, can reduce the damage in each conduction, reduce the switching frequency, can reduce the switching frequency per unit time. Both methods can reduce switch damage. 4, soft switch technology, the power supply circuit is in the full bridge rectifier circuit added capacitors and diodes. Diode in the switch tube conduction clamping effect, and constitute the discharge control circuit, discharge discharge flow. The capacitor is charged by the battery under the effect of flyback voltage, the voltage cannot be suddenly increased, when the voltage is relatively high, the current is already 0. That will keep the switch from wearing out too much.   MOS tube driver 1, compared with the dual optical crystal triode, generally think that MOS tube conduction without electricity flow, if the GS voltage is higher than a certain value, it will be ok 2. In the construction of MOS tube, it can be seen that there are parasitic capacitors between GS and GD, while the drive of MOS tube is actually to charge the capacitor battery. The capacitor's battery must be charged at a current rate, which is high because the capacitor's battery can be treated as a short-circuit fault. When selecting/designing a MOS tube drive, be aware of the size of the short-circuit capacity that can be presented in a flash. 3, widely used for high-grade driving NMOS, conducting must be the gate voltage more than the source voltage. The source voltage and drain voltage (Vcc) of high-grade driven MOS tube are the same, so the gate voltage is 4V or 10V larger than the Vcc. If in the same system software, to obtain a higher voltage than the Vcc, you need a professional boost circuit. Many motor drivers are integrated charge pump, it should be noted that the appropriate external capacitor should be selected to obtain sufficient short-circuit capacity to drive the MOS tube. 4. The 4V or 10V mentioned above are the common on-off voltage of MOS tube, so the design scheme must naturally have a certain capacity. And the higher the voltage, the faster the conduction rate and the smaller the conduction resistor. Nowadays, MOS with lower conduction voltage is useful in different industries, but in the electronic control system of 12V car, 4V conduction is generally enough.     MOS tubes use power circuits The most obvious characteristic of MOS tube is the good switching characteristic, so it is widely used in the power circuit of the switch of necessary electronic devices, such as switch power supply and motor drive power supply circuit, as well as lighting lamps. With today's MOS drivers, there are a few specific requirements: 1. Bottom pressure application When the 9V switching power supply is applied, at the moment, if the traditional totem pole structure is applied, because the be of the audion only loses 0.7V up and down, the voltage finally loaded into the gate is only 4.3V. At the moment, the MOS tube with the error gate voltage of 4.9V has certain risks. The same problem arises where 3V or other bottom voltage switching power supplies are used. 2. Wide voltage application The input voltage is not a number; it varies with time or other factors. This change causes the DRIVE voltage shown to the MOS tube by the PWM circuit to be not stable. In order to make MOS tubes safer under high gate voltage, many MOS tubes are embedded with voltage stabilizer tubes to compulsively limit the amplitude of GATE voltage. In such cases, when the presented drive voltage exceeds the voltage of the regulator tube, a large static data function loss occurs. In addition, if the basic principle of resistance voltage division is simply used to reduce gate voltage, the MOS tube works well when the input voltage is relatively high, but the gate voltage is not enough when the input voltage is reduced, resulting in insufficient conduction and thereby improving the function loss. 3, in the power module, the common switch power supply IC immediately drives the MOS tube. In applications, attention should be paid to the two main parameters, the maximum current of the larger drive and the parasitic capacitance of the MOS tube. Here, the driving capability of the SWITCH power IC, the size of the MOS parasitic capacitance, and the resistance value of the drive resistor will all harm the MOS transistor switching rate. If the parasitic capacitance of MOS tube is relatively large and the driving working ability of switch power supply IC is insufficient, the driving working ability must be improved on the drive power supply circuit. Totem pole power supply circuit is often used to improve the driving working ability of switch power supply IC. At present, none of the various MOS tube drive power circuit is the best. It must be based on the actual application by the customer, combined with the user manual presented by the MOS tube manufacturer, and continuously improve the power circuit and main parameters, so as to polish and polish the best drive plan for its own use.

功率半导体器件是电力电子技术及其应用装置的基础，是推动电力电子变换器发展的主要源泉。功率半导体器件处于现代电力电子变换器的心脏地位，它对装置的可靠性、成本和性能起着十分重要的作用。40年来，普通晶闸管（Thyristor，SCR）、门极关断晶闸管（GTO）和绝缘栅双极型晶体管（IGBT）先后成为功率半导体器件的发展平台。能称为“平台”者，一般是因为它们具备以下几个特点：①长寿性，即产品生命周期长；②渗透性，即应用领域宽；③派生性，即可以派生出多个相关新器件家属。 电力电子变换器的功率等级覆盖范围非常广泛，包括小功率范围（几W到几kW），如笔记本电脑、冰箱、洗衣机、空调等；中功率范围（10kW到几MW），如电气传动、新能源发电等；大功率范围（高达几GW），如高压直流（HVDC）输电系统等。     电力电子变换器的应用领域越来越广泛，同时也对功率半导体器件提出了更高的性能需求。继前些年推出集成门极晶闸管（IGCT）和电子注入增强型栅极晶体管（IEGT）后，如今采用碳化硅（SiC）和氮化镓（GaN）材料的新型功率器件已经应运而生。目前，功率半导体的发展主要是其功率承受能力和开关频率之间的矛盾，往往功率越大，耐压越高，允许的开关频率就越低。从功率半导体器件的个体来说，大功率和高频化仍是现阶段发展的两个重要方向。 功率半导体器件应用需要考虑大功率电路应用的特性，如绝缘、大电流能力等，在实际应用中，以动态的“开”和“关”为运行特征，一般不运行在放大状态。由功率半导体器件构成的电力电子变换器实施的是电磁能量转换，而不是单纯的开/关状态，它的很多非理想应用特性在电力电子变换器中起着举足轻重的作用。要用好功率半导体器件，既要熟悉电力电子变换器的拓扑，更要充分掌握器件本身的特性。

一说起IGBT，半导体制造的人都以为不就是一个分立器件(Power Disceret)嘛，都很瞧不上眼。然而他和28nm/16nm集成电路制造一样，是国家“02专项”的重点扶持项目，这玩意是现在目前功率电子器件里技术最先进的产品，已经全面取代了传统的Power MOSFET，其应用非常广泛，小到家电、大到飞机、舰船、交通、电网等战略性产业，被称为电力电子行业里的“CPU”，长期以来，该产品（包括芯片）还是被垄断在少数IDM手上(FairChild、Infineon、TOSHIBA)，位居“十二五”期间国家16个重大技术突破专项中的第二位（简称 “02专项”）。 究竟IGBT是何方神圣？让我们一起来学习它的理论吧。 1、何为IGBT？ IGBT全称为绝缘栅双极型晶体管(Insulated Gate Bipolar Transistor)，所以它是一个有MOS Gate的BJT晶体管。奇怪吧，它到底是MOSFET还是BJT？其实都不是又都是。不绕圈子了，他就是MOSFET和BJT的组合体。 我在前面讲MOSFET和BJT的时候提到过他们的优缺点，MOSFET主要是单一载流子(多子)导电，而BJT是两种载流子导电，所以BJT的驱 动电流会比MOSFET大，但是MOSFET的控制级栅极是靠场效应反型来控制的，没有额外的控制端功率损耗。所以IGBT就是利用了MOSFET和BJT的优点组合起来的，兼有MOSFET的栅极电压控制晶体管(高输入阻抗)，又利用了BJT的双载流子达到大电流(低导通压降)的目的 (Voltage-Controlled Bipolar  Device)。从而达到驱动功率小、饱和压降低的完美要求，广泛应用于600V以上的变流系统如交流电机、变频器、开关电源、照明电路、牵引传动等领域。     2、传统的功率MOSFET 为了等一下便于理解IGBT，我还是先讲下Power MOSFET的结构。所谓功率MOS就是要承受大功率，换言之也就是高电压、大电流。我们结合一般的低压MOSFET来讲解如何改变结构实现高压、大电流。     1)高电压：一般的MOSFET如果Drain的高电压，很容易导致器件击穿，而一般击穿通道就是器件的另外三端(S/G/B)，所以要解决高压问题必须堵死这三端。Gate端只能靠场氧垫在Gate下面隔离与漏的距离(Field-Plate)，而Bulk端的PN结击穿只能靠降低PN结两边的浓度，而最讨厌的是到Source端，它则需要一个长长的漂移区来作为漏极串联电阻分压，使得电压都降在漂移区上就可以了。 2) 大电流：一般的MOSFET的沟道长度有Poly CD决定，而功率MOSFET的沟道是靠两次扩散的结深差来控制，所以只要process稳定就可以做的很小，而且不受光刻精度的限制。而器件的电流取决于W/L，所以如果要获得大电流，只需要提高W就可以了。 所以上面的Power MOSFET也叫作LDMOS (Lateral Double diffusion MOS)。虽然这样的器件能够实现大功率要求，可是它依然有它固有的缺点，由于它的源、栅、漏三端都在表面，所以漏极与源极需要拉的很长，太浪费芯片面积。而且由于器件在表面则器件与器件之间如果要并联则复杂性增加而且需要隔离。所以后来发展了VDMOS(Vertical DMOS)，把漏极统一放到Wafer背面去了，这样漏极和源极的漂移区长度完全可以通过背面减薄来控制，而且这样的结构更利于管子之间的并联结构实现大功率化。但是在BCD的工艺中还是的利用LDMOS结构，为了与CMOS兼容。 再给大家讲一下VDMOS的发展及演变吧，最早的VDMOS就是直接把LDMOS的Drain放到了背面通过背面减薄、Implant、金属蒸发制作出来的，他就是传说中的Planar VDMOS，它和传统的LDMOS比挑战在于背面工艺。但是它的好处是正面的工艺与传统CMOS工艺兼容，所以它还是有生命力的。但是这种结构的缺点在于它沟道是横在表面的，面积利用率还是不够高。

在智能家电产品通电后，MCU就开始启动，由于MCU所消耗的电流只占整个家电产品消耗功率的很小一部分，所以通常对其工作电流大小不作要求，只要产品可以正常工作即可。一直到近几年，由于人们日益重视环保，市场上开始关注节能低碳的电子产品，对家电及电子产品的低耗能也提高了要求，因此低功耗MCU在家庭的各种电器产品上开始占据重要地位。 　　低功耗MCU的需求原因 　　在电子产品上需要低功耗MCU的原因大部分出自环保的考虑：一方面，地球温室效应造成的问题需要大家通过节约能源来解决；另一方面，大量的电池若没有按正常渠道回收可能会造成土地和水资源污染。具体来说，低功耗MCU的需求可以归纳为以下几种情况。 　　1. 一般家电电源来自电源插头，当插头插在插座上，即使家电没有启用也会消耗一些功率，通常来说这些消耗的功率越少越好。 　　2. 家电若具有时钟功能，则当插头离开插座后，时钟所需的电源需靠内部电池提供，因此电池必须能够维持较长时间。 　　3. 具有遥控功能的电器需维持较低的待机电流。 　　4. 使用电池供电的电器用品其电池使用寿命要越长越好。 　　5. 使用太阳能电池来代替使用一般电池的电子产品。 许多家电、音响、电视都会有遥控器接收电路，以方便使用该电器的各种选项及设定功能。当这些电器关闭时，并不是完全关闭电源，遥控器的接收电路还在继续工作，除非把插头拔掉，否则待机电流一直存在，这也会造成能源的浪费。若是能把此时的耗电降至，对节能省电也有不小的帮助，接收遥控器电路的MCU如果本身使用低功耗MCU就是降低此时待机电流的好方法。     　　为了能够随时侦测到遥控器发射的红外线载波信号，红外线的接收电路必须永远保持工作状态，为此基本的耗电是免不了的，节能的可行方法是将MCU的系统频率降低，让MCU运行在可以接受红外线遥控器信号的工作频率，从而节省其工作时的耗电。      家用电器的省电设计构思       对使用电池的产品而言，在符合成本的原则下，应选择消耗功率的MCU，因为电池废弃物的处理对环境影响很大，且电池内部的重金属会污染水资源及土地。比如家庭中厨房秤、遥控器以及某些具有时钟功能的小家电都会使用到电池，若是使用低功耗MCU，则可以减少电池用量，从而减少环境污染。减少电池用量可以从降低MCU的工作电流做起，同样功能的MCU，若是选择消耗电流减少一半的，则电池使用寿命将增加一倍，这样不仅减少购买电池的费用，也减少了电池的使用量。 　　太阳能电池，这可更进一部减少电池的用量，对环境保护将发挥的效果。我们常看到一些电子计算器使用太阳能来供电，如果低功耗MCU工作的电流及电压都大幅降低，则也有机会使用太阳能电池。在功耗需求较低的产品上，如温度计、湿度计、体温计、电子表、LCD显示电子钟等，使用小瓦数的太阳能电池就足够应付MCU所消耗的电流。太阳能是环保的能源，只要有太阳，产品就可以工作，不需担心电池耗尽问题，也不需更换电池，因而也不会造成环境污染。 特诺半导体有限公司，定制单片机开发项目，针对小家电、生活电器、数码设备、无线设备等项目开发，都有属于自己独到的理解，如果你有其他的需要，例如功能的定制、方案的定制等 单片机_MCU_微型控制器—特诺半导体   特诺半导体专注于研发高抗干扰性、高可靠性的通用型和专用型的8位和32位微控制器产品（MCU），并为客户提供相关的应用开发工具和解决方案。

N沟MOS晶体管金属-氧化物-半导体(Metal-Oxide-SemIConductor)结构的晶体管简称MOS晶体管，有P型MOS管和N型MOS管之分。MOS管构成的集成电路称为MOS集成电路，而PMOS管和NMOS管共同构成的互补型MOS集成电路即为CMOS集成电路。  由p型衬底和两个高浓度n扩散区构成的MOS管叫作n沟道MOS管，该管导通时在两个高浓度n扩散区间形成n型导电沟道。n沟道增强型MOS管必须在栅极上施加正向偏压，且只有栅源电压大于阈值电压时才有导电沟道产生的n沟道MOS管。n沟道耗尽型MOS管是指在不加栅压（栅源电压为零）时，就有导电沟道产生的n沟道MOS管。     NMOS集成电路是N沟道MOS电路，NMOS集成电路的输入阻抗很高，基本上不需要吸收电流，因此，CMOS与NMOS集成电路连接时不必考虑电流的负载问题。NMOS集成电路大多采用单组正电源供电，并且以5V为多。CMOS集成电路只要选用与NMOS集成电路相同的电源，就可与NMOS集成电路直接连接。不过，从NMOS到CMOS直接连接时，由于NMOS输出的高电平低于CMOS集成电路的输入高电平，因而需要使用一个（电位）上拉电阻R，R的取值一般选用2～100KΩ。N沟道增强型MOS管的结构在一块掺杂浓度较低的P型硅衬底上，制作两个高掺杂浓度的N+区，并用金属铝引出两个电极，分别作漏极d和源极s。然后在半导体表面覆盖一层很薄的二氧化硅(SiO2)绝缘层，在漏——源极间的绝缘层上再装上一个铝电极,作为栅极g。在衬底上也引出一个电极B，这就构成了一个N沟道增强型MOS管。MOS管的源极和衬底通常是接在一起的(大多数管子在出厂前已连接好)。它的栅极与其它电极间是绝缘的。图(a)、(b)分别是它的结构示意图和代表符号。代表符号中的箭头方向表示由P(衬底)指向N(沟道)。P沟道增强型MOS管的箭头方向与上述相反，如图(c)所示。 N沟道增强型MOS管的工作原理（1）vGS对iD及沟道的控制作用① vGS=0 的情况从图1(a)可以看出，增强型MOS管的漏极d和源极s之间有两个背靠背的PN结。当栅——源电压vGS=0时，即使加上漏——源电压vDS，而且不论vDS的极性如何，总有一个PN结处于反偏状态，漏——源极间没有导电沟道，所以这时漏极电流iD≈0。② vGS>0 的情况若vGS＞0，则栅极和衬底之间的SiO2绝缘层中便产生一个电场。电场方向垂直于半导体表面的由栅极指向衬底的电场。这个电场能排斥空穴而吸引电子。排斥空穴：使栅极附近的P型衬底中的空穴被排斥，剩下不能移动的受主离子(负离子)，形成耗尽层。吸引电子：将 P型衬底中的电子（少子）被吸引到衬底表面。（2）导电沟道的形成：当vGS数值较小，吸引电子的能力不强时，漏——源极之间仍无导电沟道出现，如图1(b)所示。vGS增加时，吸引到P衬底表面层的电子就增多，当vGS达到某一数值时，这些电子在栅极附近的P衬底表面便形成一个N型薄层，且与两个N+区相连通，在漏——源极间形成N型导电沟道，其导电类型与P衬底相反，故又称为反型层，如图1(c)所示。vGS越大，作用于半导体表面的电场就越强，吸引到P衬底表面的电子就越多，导电沟道越厚，沟道电阻越小。开始形成沟道时的栅——源极电压称为开启电压，用VT表示。上面讨论的N沟道MOS管在vGS＜VT时，不能形成导电沟道，管子处于截止状态。只有当vGS≥VT时，才有沟道形成。这种必须在vGS≥VT时才能形成导电沟道的MOS管称为增强型MOS管。沟道形成以后，在漏——源极间加上正向电压vDS，就有漏极电流产生。

电气设备的故障多由元器件坏损而致,其他原因引起电子产品的故障也常常造成 电子元器件的损坏，导致机器设备不可以工作中。因此，要想辨别电子元器件的优劣，那把握元器件损坏的原因、特性及主要表现,对搜索故障点和恢复机器设备是十分关键的。下边就为大伙儿详细介绍几类常见电子元器件损坏原因及查找方法。       一、电阻损坏的特点 电阻是电器设备中数量最多的元件。电阻损坏以开路最常见，阻值变大较少见，阻值变小十分少见。常见的有碳膜电阻、金属膜电阻、线绕电阻和保险电阻几种。前两种电阻应用最广，其损坏的特点：一是低阻值（100Ω以下）和高阻值（100kΩ以上）的损坏率较高，中间阻值（如几百欧到几十千欧）的极少损坏；二是低阻值电阻损坏时往往是烧焦发黑，很容易发现，而高阻值电阻损坏时很少有痕迹。线绕电阻一般用作大电流限流，阻值不大。圆柱形线绕电阻烧坏时有的会发黑或表面爆皮、裂纹，有的没有痕迹。水泥电阻是线绕电阻的一种，烧坏时可能会断裂，否则也没有可见痕迹。保险电阻烧坏时有的表面会炸掉一块皮，有的也没有什么痕迹，但绝不会烧焦发黑。根据以上特点，在检查电阻时可有所侧重，快速找出损坏的电阻。 二、电解电容损坏的特点 电解电容在电器设备中的用量很大，故障率很高。电解电容损坏有以下几种表现： 1、是完全失去容量或容量变小； 2、是轻微或严重漏电； 3、是失去容量或容量变小兼有漏电。 查找损坏的电解电容方法有： （1）看：有的电容损坏时会漏液，电容下面的电路板表面甚至电容外表都会有一层油渍，这种电容绝对不能再用；有的电容损坏后会鼓起，这种电容也不能继续使用； （2）摸：开机后有些漏电严重的电解电容会发热，用手指触摸时甚至会烫手，这种电容必须更换； （3）电解电容内部有电解液，长时间烘烤会使电解液变干，导致电容量减小，所以要重点检查散热片及大功率元器件附近的电容，离其越近，损坏的可能性就越大。 三、集成电路损坏的特点 集成电路内部结构复杂，功能很多，任何一部分损坏都无法正常工作。集成电路的损坏也有两种：彻底损坏、热稳定性不良。彻底损坏时，可将其拆下，与正常同型号集成电路对比测其每一引脚对地的正、反向电阻，总能找到其中一只或几只引脚阻值异常。对热稳定性差的，可以在设备工作时，用无水酒精冷却被怀疑的集成电路，如果故障发生时间推迟或不再发生故障，即可判定。通常只能更换新集成电路来排除。