The Kynix Blog - General electronic semiconductor

With the development of science and technology, electronic products are changing with each passing day. Also, electronic assembly technology is facing challenges. Following the development of electronic technology, people work harder to make innovations in electronic assembly technology.  And in this context, a flexible circuit board invented used which made of the thin-and-flexible polymer film. It can complete the application of surface mounting technology and bend without affecting the normal circuit operation.  Clear Flexible Printed Circuit Catalog I. Brief IntroductionII. Five Main Materials for Flexible Circuit Board2.1 Insulating Firm2.2 Bonding Sheet2.3 Copper Foil2.4 Overburden2.5 Reinforcement PlateFAQ I. Brief Introduction Today's flexible electrons are all made of SMT technology, so they are thin and exquisite with insulation thickness of fewer than 25 μm. It can be bent arbitrarily and rolled into a cylinder. And it makes full use of three-dimensional volume. It breaks the stereotype of the traditional area of use and creates the ability to make full use of the shape of the volume, which can significantly enhance the effective density of use in the length of the conductor currently routinely used per unit area, forming a high-density assembly. In recent years, flexible circuit technology has been applied in various fields, such as radio communication, computer, and automobile electronic equipment. Unlike in the past, flexible circuits have been used as substitutes for rigid cables, and they have been used as substitutes for rigid circuits and printed circuit boards (PCB) in applications where thin or three-dimensional circuits are required. In order to meet the requirements of rigid and flexible applications, it is combined flexible circuit technology in the rigid circuit board, making flexible circuit board used widely. The functions of the flexible circuit board can be divided into four categories, including the lead line, printed circuit, connector, and IntegraTIon of FuncTIon, which covers the computer, Computer peripheral auxiliary system, civil electrical appliances and cars, and other areas. For different applications, the material of the flexible circuit board should select carefully. And the followings are some rules of the five main materials of the flexible circuit board.  II. Five Main Materials for Flexible Circuit Board 2.1 Insulating FirmThe insulating film is flexible and can be used as the insulation carrier of the circuit board to form the basic layer of the circuit. When selecting the flexible dielectric film, the heat resistance, overlay, thickness, mechanical properties and electrical properties of the material should be tested.  Insulation film is usually available on the market, the most common is polyimide and polyester materials. Of all the flexible circuit manufacturers in the United States, nearly 80% use polyimide film as the material for flexible circuits, and about 20% use polyester film. Because polyimide material is nonflammable, stable geometry, high anti-tear, and able to withstand high temperature during welding. 2.2 Bonding Sheet It is made up of two insulating films coated with adhesive, the ability is gluing the film to the foil, and the film to the film in the flexible circuit, In order to provide mechanical support and eliminate stress during insertion of components and connectors. It also can provide protection and electrical insulation. Different types of adhesive sheets can be used for different film substrates, such as polyester bonding sheets and polyimide bonding sheets are different, for example, the polyimide substrate has epoxy resin and acrylic acid. 2.3 Copper FoilCopper foil is a conductor layer that is coated on the insulating substrate and then selectively etched to form a conductive line. The vast majority of this copper foil is rolled copper foil or electrolytic copper foil. The ductility and bending resistance of the rolled copper foil is better than that of the electrolytic copper foil.  The elongation of the rolled copper foil is 20%~45% and the electrolytic copper foil is 4%~40%. The commonly used thickness of copper foil is 35um (1oz), also they have 18um (O.5oz), 70um (2oz), or even 105um (30z). According to different applications, we have to choose different forms of copper foil.  If only to replace wires and connectors, and to reduce manufacturing time and cost, the best choice is electrolytic copper foil. The electrolytic copper foil will increase the weight of copper to level the load capacity of the current, thus obtaining the suitable width of the copper sheet. 2.4 OverburdenThe brand, Novaclad, created by Sheldahl, applies the vacuum metal spraying technology which is a patent. It is a technology that applying a thin layer of pure copper to the surface of a polyimide film, then electroplating into a specific thickness to form the substrate of Novaclad. The base material is used in Novaflex, a flexible circuit without adhesive. After all the circuits have been made, a layer of Novaflex insulation is applied. The Novaflex is designed to work under harsh conditions, and Novaflex without adhesive provides better flexibility, chemical resistance, high-temperature properties, and maximum heat dissipation properties. 2.5 Reinforcement PlateThe reinforced plate to the local position of the flexible plate plays the role of super supporting and strengthening the flexible film substrate, which is convenient for the connection, fixation, or other functions of the PCB. According to different needs, the reinforcement board materials commonly use polyester, polyimide sheet, epoxy fiberglass cloth plate, phenolic-aldehyde paper board, steel plate, aluminum plate, etc.  FAQ 1.What is a flexible circuit board?A flexible printed circuit board features a combination of several printed circuits as well as components that are positioned on a flexible substrate. These circuit boards are also known as flex circuit boards, flex PCBs, flex circuits, or flexible printed circuits. 2. What is flex circuit used for?Flex circuits are often used as connectors in various applications where flexibility, space savings, or production constraints limit the serviceability of rigid circuit boards or hand wiring. A common application of flex circuits is in computer keyboards; most keyboards use flex circuits for the switch matrix. 3. What are flexible circuit boards made of?Flexible circuits are thin, light-weight electrical circuits that conform to small spaces and contoured shapes. They consist of conductive strips of metal, usually copper, encapsulated with an insulating dielectric material made of polyimide or a solder mask. 4. Where are flexible PCBS used?a. Automobiles.b. Consumer electronics including smartphones, SLR cameras and camcorders,c. Medical systems and devices such as heart monitors, pacemakers and the bionic knee.d. Motion systems.e. GPS systems.f. Aerospace and avionics systems. 5. When was the first flex printed circuit made?From early applications during World War II to the present, growth and proliferation for flex circuits and flexible printed circuit boards continues exponentially. A flexible circuit in its purest form is a vast array of conductors bonded to a thin dielectric film. 6. What are the advantages and disadvantages of flexible circuit boards?The advantages of the flexible circuit board are mainly high assembly density, which can save the connection of redundant cables, in addition, it has good bendability, high flexibility, small size, simple structure, and convenient installation.Disadvantages of flexible circuit boards: 1. High initial cost 2. Difficult to change and repair 3. Size limited 4. Improper operation and easy damage, etc. 7. What do flexible circuit boards and rigid circuit boards mean?a.  Flexible circuit boards are used more in digital products. The difference between it and the rigid circuit board is that the substrate of the circuit board is different. As the name implies, the board can be bent and softer.b. "Multilayer board" and "double-sided board" mainly refer to the number of sides of wiring on the circuit board. Above 2 layers are multi-layer boards.From the perspective of the process flow, the multilayer board needs to be processed by the inner layer map, and the outer layer can be processed after being pressed. The processing flow of the outer layer is basically the same as the processing flow of the double-sided board. 8. What is the temperature resistance of fpc flexible circuit boards?FPC flexible circuit board can withstand high temperature of 280 degrees, about 1 hour. However, the recommended temperature for normal use is not less than -20 and not higher than 80. 9. With flexible circuit boards, why pcb hard printed circuit boards are still not eliminated?For PCBs that need to use plug-in components, only rigid boards can be used, which is what you call rigid boards; for many PCBs with stress requirements, only rigid boards can be used. The cost of flexible boards is currently much higher than rigid boards, more than doubled. And the straight-through rate of rigid boards is higher than that of flexible boards 10.Classification of flexible circuit boards?According to the combination of base material and copper foil, flexible circuit boards can be divided into two types: flexible boards with glue and flexible boards without glue. Among them, the price of the glueless flexible board is much higher than that of the glued flexible board, but its flexibility, the bonding force of the copper foil and the substrate, and the flatness of the pad are also better than the glued flexible board. You May Also LikeSwitching Power Supply Tutorial: 4V～16VWhat is A MCU’s internal Structure: Single Chip Micro-ComputerPCB Wring Tutorial: A/D converterMonitoring Technology in Communication Power Supply: Application GuideDIY CommunityDIY Flxible Printed CircuitsMake Flexible Circuit Boards Using A 3D Printer

  This technical article will introduce 10 common problems you might encounter with when apply inverter in your project.     What is Inverter? This video explains what inverter is and which inverter you need in your project.   1. Leakage Circuit Breakers are Prone to Tripping When Using Variable-Frequency Drive. The output waveform of the ac drive contains higher harmonic, and the leakage current will be generated between the motor and the cable between the inverter and the motor, what’s more, the leakage current is much larger than that of the motor driven by the power frequency.   The leakage current at the output side of the inverter is about three times that of the power frequency operation, in addition, adding the leakage current of the motor. The operation current of the selected leakage protector should be 10 times greater than that of the leakage current at the power frequency.    2. The Temperature Rise of the Motor Higher Than That of the Power Frequency When the AC Drive is Used. The output voltage waveform of the inverter is not sinusoid wave, but distorted wave, the motor current under rating torque is about 10% more than the power frequency, so the temperature rise is slightly higher than the power frequency.   3. How to Adjust Torque Boost. A. When the torque boost setting is too high and the load is very small, the current will increase due to the magnetic flux saturation of the motor core, and the variable-frequency drive may run overcurrent protection. Therefore, in order to improve the motor efficiency, the setting should be reduced when the load is lightened.   B. For heavy load, the voltage drop loss caused by stator winding and motor cable can be compensated by increasing the torque-boost setting value.   4. Carrier Frequency and How to Adjust It. A. The output voltage of the SPWM converter is a series of pulses whose pulse frequency is equal to the carrier frequency.   B. In the current of the motor, there is a strong harmonic component of the carrier frequency, which will cause the oscillation of the iron core of the motor and emit noise. If the frequency of the noise is equal to the inherent oscillation frequency of the motor core, the noise will increase. In order to reduce it, the frequency inverter can adjust the carrier frequency in a certain range to avoid the resonance frequency of the noise.   C. Harmonic component of carrier frequency has strong radiation, which will cause electromagnetic interference to external electronic equipment.   D. From the point of view of improving the current waveform, the higher the carrier frequency, the smoother the current waveform. However, the electromagnetic interference to the outside is also stronger.   E. The higher the carrier frequency is, the less the motor noise is, but the greater the switching loss of power device is, the more serious the frequency converter is. The lower the carrier frequency, the greater the motor noise, and the switching loss of the inverter is lower too.   5. DC Brake (1) It is used to control the precise parking of some equipments, to avoid "crawling" at low speed, and to start the function at the time of shutdown.   (2) Since the frequency conversion speed control system always starts from the lowest frequency, if the motor starts with a certain speed, and the frequency converter does not set the speed tracking function, the overcurrent or overvoltage will appear.   6. Should the Rating Frequency of the Load Motor be the Same as That of the Motor? This function parameter:  the fundamental frequency   A. If the fundamental frequency is set below the rated frequency of the motor, the motor voltage will increase, and the output voltage will increase will lead to the increase of the magnetic flux of the motor, making the saturation of the flux, the distortion of the exciting current, and the occurrence of a very large peak current. As a result, the converter tripped because of overcurrent.   B. If the fundamental frequency is higher than the rated frequency of the motor, the voltage and load capacity of the motor will decrease.   Difference Compensation Depending on the magnitude of the load current, the output frequency of the ac drive (internal improvement, actual display constant) is appropriately increased to compensate for the increase in the rotational difference due to the increase in the load.   7. AVR Function When the power network voltage drops, the reference frequency is reduced automatically and the flux K*U/F is constant, so as to ensure the load capacity of the motor unchanged.   Kinds of Common Load: 1)Constant Torque Load Although the rotational speed is different, resistance torque load is basically constant. The output power is proportional to the rotational speed, like the belt conveyer.   2)Constant Power Load Although the rotational speed is different, load power is basically constant. The output torque is proportional to the rotational speed. Like a winding device, such as a thin film or sheet.   3)Square Load The resistance torque load is proportional to the square of the rotational speed. Such as fans and pumps.     8. Frequency Control of Several Special Motors (1) Wound Rotor Asynchronous Motor The rotor winding of a wound rotor asynchronous motor is a set of star-schema three-phase windings. The end points of the three-phase windings are connected to the three collector rings, through it to collect the brush and the external resistor (starting or adjusting speed).   After adopting the frequency converter to adjust the speed, the rotor winding does not need to connect the resistor, so the terminal of the three-phase winding can be connected directly with the wire.   (2) Magnetic Brake Motor It is composed of ordinary motor and magnetic brake. The motor and the magnetic brake are connected to the power supply at the same time, and the armature of the electromagnet is absorbed, which makes the motor rotor rotate freely.   After cutting off the power supply, the excitation winding of the brake powers off and the rotor stops quickly. The excitation winding circuit of the electromagnet should be connected to the input side of the frequency converter after adopting the frequency converter, and turned on at the same time as motor.   9. Capacity Selection of a Single Inverter with Multiple Motors.  A. Simultaneous Start-up The rated current of the inverter should be greater than the sum of the maximum operating current of several motors.   B. Starting Time in Turn The rated current of the converter shall be greater than the sum of the rated current of the motor other than the maximum motor plus the seven-times rated current of the maximum motor.     10. Interference Mode and Treatment of Inverter Propagation Mode 1) Radiatedradiated Interference  2) Conducted Interference   Anti-jamming Measures Interference signals propagating by radiation are weakened mainly by wiring and shielding the radioactive sources and the interfered lines.   For the interference signal propagating through the circuit, the filter, reactor or magnetic ring are added to the input and output side of the inverter.   The Specific Methods and Precautions are as Follows:   (1) Signal lines and power lines should be vertically crossed or slotted separately. (2) Do not use different metal wires to connect to each other. (3) Shielding tube (layer) should be reliably grounded and ensure continuous and reliable grounding across the whole length. (4) Twisted-pair shielded cables should be used in signal circuits. (5) Grounding contacts of the shield layer should away from the frequency converter as far as possible, and separated from the connecting location of the frequency converter. (6) The magnetic ring can be used on the input power line and output line of the inverter. The method is as follows: the input line goes around four times in the same direction and the output line around three times in the same direction with magnetic rings. When winding the wire, the magnetic rings should close the frequency converter as far as possible. 7) Shielding and other anti-interference measures, such as the temperature control of injection molding machine, can be taken for the equipment.   FAQ   1. What does an inverter do? Inverters are also called AC Drives, or VFD (variable frequency drive). They are electronic devices that can turn DC (Direct Current) to AC (Alternating Current). It is also responsible for controlling speed and torque for electric motors.   2. What is the purpose and function of an inverter? An inverter converts the DC electricity from sources such as batteries or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage.   3. What is inverter and how it works? The first thing to keep in mind when it comes to enriching your understanding of the internal structure of an inverter device, is that the converter circuit converts alternating current (AC) coming from the power source into direct current (DC), and the inverter circuit changes the converted direct current (DC) back into alternating current (AC). They work as a set.    4. Does inverter really save electricity? An inverter is energy saving technology that eliminates wasted operation in air conditioners by efficiently controlling motor speed. ... Compared to non-inverter type air conditioners, air conditioners with inverters have less power loss and can save in energy.   5. What can you plug into an inverter? A power inverter changes DC power from a battery into conventional AC power that you can use to operate all kinds of devices ... electric lights, kitchen appliances, microwaves, power tools, TVs, radios, computers, to name just a few.   6. How many hours can an inverter last? Usually, you can expect your inverter battery to last anywhere from 5 to 10 hours when it is fully charged. Most inverters show an estimated as soon as they start powering the appliances.   7. How many watts inverter do I need for home? Peak output is the wattage that an inverter can supply for short periods of time when the demand spikes, while continuous output is the limit for normal operation. If your devices draw a combined total of 600 watts, then you need to buy an inverter that has a continuous output rating of 600 watts   8. Is UPS and inverter same? The UPS is the electric device that has a rectifier for providing the backup power to the system whereas the inverter converts DC into AC. The main function of the UPS is to store the electric supply whereas the inverter converts the AC power into DC power.   9. Where should I install an inverter in my house? To install the inverter, place the inverter assembly on top of the main housing chassis in such a way that the inverter faces forward. Remember to remove power at the electricity board meter of the home.   10. What size inverter do I need to run a laptop? Volts (120) x Amps = Watts. For example if your DVD player draws 100 watts and your laptop another 100 watts, a minimum 300-watt inverter is recommended. If the item is motor driven, it requires additional start-up (surge) wattage (typically 2-3 times the continuous wattage required) to start the device.   11. What are the types of inverter? There are 3 major types of inverters - sine wave (sometimes referred to as a "true" or "pure" sine wave), modified sine wave (actually a modified square wave), and square wave.   12. How long will a 12V battery last with an inverter? For example: 12V 100Ah battery will be able to power 1000W inverter for ~30 minutes, 12V 200Ah battery will be able to power 2000W inverter for ~30 minutes, etc.   13. Is inverter An gate? An Inverter is a Logic Gate that has only one Input, it outputs the opposite Logic State of its Input. The Inverter is also called NOT Gate.   14. What is the disadvantage of inverter AC? If an inverter AC has lower capacity than requirement, the compressor runs at higher speeds for longer duration of time thereby increasing power consumption. On the other hand, if an inverter AC has higher capacity than heat load, it will run for short cycles and render the room over cooled and uncomfortable.   15. What is the difference between Eco mode and UPS mode in an inverter? In eco-mode the load is normally powered by the bypass path, allowing raw mains power to supply the load, and the UPS inverter is engaged only when the utility mains fails. In eco-mode the UPS inverter operates in a “standby” mode. In principle, this is a simple change in the control software of the UPS. You May Also Like About Operational Amplifier LM358: 24 Classical Circuits Switching Power Supply Guide: Protection Circuit Simplify Current Monitoring by Using Diode | Power Supply Negative End A Complete Guide to Solid State Drive (SSD)

    Circuit protection is a frequently discussed topic, and the various types of circuit protection differ due to the various problems in the circuit. Short-circuit, overload, grounding, and lightning strikes are the most common faults in power supply systems. To ensure the safe and dependable operation of the power supply system, protection devices must be installed to monitor the working conditions of the power supply system, detect faults in time, and cut off the power supply of the faulty equipment, preventing the accident from spreading. In general, the protection circuit is made up of various relays, signal indicating devices, and other components. This blog provides an in-depth discussion on several circuit protections. Below is an introduction video about short circuit protection. DIY Short Circuit (Overcurrent) Protection   Catalog   I Introduction to circuit protection II Switching power principle and characteristics      2.1 Operational principle of switching power      2.2 Characteristic of switching power III DC Switching power supply protection      3.1 Overcurrent protection circuit      3.2 Overvoltage protection circuit      3.3 Soft start protection circuit        3.4 Overheat protection circuit IV Conclusion FAQ   I Introdcution to circuit protection The operation of electronic equipment can not be separated from electricity, so DC switching power supply which can control the electricity is playing a more and more important role. And it has entered various fields of electronics and electrical equipment: SPC exchange, communication, electronic testing equipment power supply and controlling equipment power supply, which are widely used DC switching power supply.  Meanwhile, with the development of many high-tech technologies, including high-frequency switching technology, soft-switching technology, power factor correction technology, synchronous rectifier technology, intelligent technology, surface installation technology, etc., switching power supply technology is constantly innovating. This provides a wide range of development for DC switching power supply.  DC current diagram   But the circuit is complex to control in the switching power supply, the transistor and the integrated device have poor resistance to electricity and thermal shock, which brings great inconvenience to the user in the process of using. In order to protect the safety of switching power supply itself and load, the overheat protection, over-current protection, over-voltage protection and soft start protection circuit are designed according to the principle and characteristics of DC switching power supply.   II Switching power principle and characteristics 2.1 Operational principle of switching power DC switching power supply is composed of input part, power conversion part, output part and control part. The power conversion part is the core of the switching power supply. It performs conversion which needed for the output on the high-frequency and unstable DC. It is mainly composed of switching transistor and high frequency transformer. Figure 1. DC Switching power supply principle Figure 1 shows the schematic diagram and equivalent schematic block diagram of DC switching power supply, which is composed of full wave rectifier, switching tube V, excitation signal, fly-wheel diode Vp, energy storage inductance and filter capacitance C. In fact, the core part of DC switching power supply is a DC transformer. 2.2 Characteristic of switching power   In order to meet the needs of users, the world's major switching power supply manufacturers are committed to the simultaneous development of new and highly intelligent components, especially by reducing the loss of the secondary rectifier. In order to improve the magnetic properties under high frequency and high magnetic flux density, power ferrite (Mn-Zn) materials have been developed. At the same time, the application of SMT technology in the field of switching power supplies has also made considerable progress. The components are arranged on both sides of the circuit board to ensure that the switching power supply is light, small and thin. Therefore, high frequency, high reliability, low power consumption, low noise, anti-interference and modularization are the development trends of DC switching power supplies. However, DC switching power supplies also have disadvantages. The DC switching power supply switch has serious interference, and its ability to adapt to harsh environments and sudden failures is weak. There is still a certain gap in microelectronics technology in developing countries. Specifically, the production technology of resistors and capacitors and the technology of magnetic materials are compared with those of some technologically advanced countries. Therefore, the manufacture of DC switching power supplies is very difficult. In most parts of the world, maintenance is difficult and the cost is high. III DC Switching power supply protection Based on the characteristics of DC switching power supply and the actual electrical condition, in order to make DC switching power supply work safely and reliably in bad environment and sudden fault, this paper designs a variety of protection circuits according to different conditions. 3.1 Overcurrent protection circuit   Figure 2. Input Overcurrent protection circuit In DC switching power supply circuit, in order to avoid short circuit and overflow damage to protect the regulator tube in the circuit, the basic method is that, when the output current exceeds a certain value, the regulator tube is in the reverse bias state, thus the circuit current is cut off automatically. As shown in Fig. 2, the over-current protection circuit consists of transistor BG2 and divider resistor R4, R5. When the circuit works normally, the base potential of BG2 is lower than that of emitter through the partial voltage interaction between R4 and R5, and the emitter junction bears reverse voltage. So the BG2 is in the cutoff state (equivalent to open circuit), which is used to stabilize the voltage. But the voltage stabilizing circuit has no effect. When the circuit is short circuit, the output voltage is zero and the emitter of BG2 is equivalent to grounding, then the BG2 is in the state of saturation conduction (equivalent to short circuit), so that the regulator tube BG1 base and emitter are close to short circuit, and in the cut-off state, the circuit current is cut off to achieve the purpose of protection.   3.2 Overvoltage protection circuit The overvoltage protection of switching regulator in DC switching power supply includes input overvoltage protection and output overvoltage protection. If the voltage of the unstabilized DC power supply (such as batteries and rectifiers) used by the switching regulator is too high, it will cause the switching regulator to fail to work properly and even damage the internal devices. Therefore, it is necessary to use the input overvoltage protection circuit in the switching power supply. Fig. 3 is a protection circuit composed of transistors and relays, in which the voltage of the input DC power supply is higher than the breakdown voltage of the zener diode, at this condition, current flows through resistor R, making diode T conducts. Following these electrical actions, relay operates and common closed contact disconnected, inputting current. The polarity protection circuit of the input power supply can be combined with the input overvoltage protection to form the polarity protection identification and overvoltage protection circuit. Figure 3. Input overvoltage protection circuit 3.3 Soft start protection circuit The circuit of switching power supply is complex, the input end of switching regulator is usually connected with small inductance and large-capacitance input filter. At start-up instant, the filter capacitor flows through a large surge current that can be several times the normal input current. Such a large surge current melts the contacts of the normal power switch or the relay and melts the input fuse. In addition, surge current can also damage capacitors, shorten their life, cause premature damage. To this end, a current-limiting resistance should be connected in the circuit, through this current-limiting resistance to charge the capacitor. In order not to consume too much power by the current limiting resistance, and avoid affecting the normal operation of the switching regulator, therefore a relay is used to connect it automatically after the transient process is finished, which makes the DC power supply directly to the switching regulator. This is called the "soft start" circuit of DC switching power supply. Figure 4. Soft start-up protection circuit When the power supply is switched on, capacitor C is charged by input voltage through rectifier bridge (D1 ~ D4) and current-limiting resistance R1 to limit the surge current. The inverter works normally when the capacitor C is charged to about 80% rated voltage. The trigger signal of thyristor is generated by auxiliary winding of main transformer, which makes thyristor switch on and short circuit current-limiting resistance R1, and the switching power supply is in normal operation state. In order to improve the accuracy of the delay time and prevent the relay operation from shaking and oscillating. The delay circuit can replace the RC delay circuit by the circuit shown in figure 4(b). 3.4 Overheat protection circuit The high integration and light weight of switching regulator in DC switching power supply greatly increase the power density per unit volume, so if the internal components of the power supply do not have a corresponding increase in the temperature of its working environment, it will inevitably make the circuit performance damaged and components life service shortened prematurely. Therefore, overheating protection circuit should be installed in high power DC switching power supply. Figure 5. Overtemperature protection circuit In this paper, the temperature relay is used to detect the internal temperature of the power supply device. When the inside of the power supply device is overheated, the temperature relay operates, which makes the alarm circuit of the whole machine in the state of alarm and realizes the protection of the overheating of the power supply.  As shown in Fig. 5 (a), the P type control gate thermal thyristor is placed near the power switch transistor in the protection circuit. According to the characteristics of the TT102 (the on-on temperature of the device is determined by the Rr value, the larger the Rr is, The lower the conduction temperature), when the temperature of the power tube or the temperature inside the device exceeds the allowable value, the thermal thyristor is switched on and the LED is lighting to give an alarm. If cooperate with photoelectric coupler which can make whole machine alarm circuit operation, protecting switch power supply.  The circuit can also be designed as shown in Fig. 5 (b) to protect the power transistor from overheating. The base current of the switching transister is bypassed by the TT201 of the N type control gate thermal thyristor, and the switch tube is cut off, also the collector current is cut off, and the overheating is prevented. IV Conclusion This blog mainly discusses various protection methods of internal devices in DC switching power supply, and introduces some concrete circuits. For a given DC switching power supply, it is very important for the security and reliability of the power supply device whether the protection circuit is perfect and set up to work necessarily. Because the protection scheme and circuit structure of switching power supply are diverse, reasonable protection scheme and circuit structure should be chosen for specific power supply devices. In practical application, several protection methods are usually used to form a perfect protection system to ensure the normal operation of DC switching power supply.   FAQ   1. What is the purpose of circuit protection? The basic goals of circuit protection are to 1) localize and isolate the condition or fault and 2) prevent and minimize any unnecessary power loss. There are several types of abnormal conditions that may occur throughout a building's life, in which an electrical system must be designed to correct or overcome.   2. What protective devices are used in circuits? Fuses, MCBs, RCDs, and RCBOs are all devices used to protect users and equipment from fault conditions in an electrical circuit by isolating the electrical supply.   3. How do you protect a circuit design? The most basic device is a fuse, a type of low resistance resistor that acts as a sacrificial device to provide over current protection, of either the load or source circuit. A fuse protects the circuit, but once it's utilized, it's kaput.   4. What are the two main circuit protection devices? The two types of circuit protection devices discussed in this chapter are fuses and circuit breakers. A fuse is the simplest circuit protection device. It derives its name from the Latin word "fusus," meaning "to melt." Fuses have been used almost from the beginning of the use of electricity.   5. What is a DC switching power supply? A Switching DC power supply (also known as switch mode power supply) regulates the output voltage through a process called pulse width modulation (PWM). The PWM process generates some high frequency noise, but enables the switching power supplies to be built with very high power efficiency and small form factor.   6. What are the differences between linear DC power supply and switching power supply? Linear power supplies deliver DC by passing the primary AC voltage through a transformer and then filtering it to remove the AC component. Switching power supplies feature higher efficiencies, lighter weight, longer hold up times, and the ability to handle wider input voltage ranges.   7. Can I use a switching power supply to drive a DC motor? A simple unregulated analog power supply may be easier and be able to supply the large starting under load current more that the switching one. DC motors are not too fussy about the supply, and will usually run quite well on unfiltered DC.   8. Do I need a switching power supply? The switching power supply implies higher efficiency due to the high switching frequency, enabling it to use a smaller, less-costly high-frequency transformer as well as lighter, less-costly filter components. Switching power supplies contain more overall components, therefore are usually more expensive.   9. What are the 3 types of power supply? There are three subsets of regulated power supplies: linear, switched, and battery-based. Of the three basic regulated power supply designs, linear is the least complicated system, but switched and battery power have their advantages.   10. What is a switching mode power supply used for? Switched-mode power supplies are used to power a wide variety of equipment such as computers, sensitive electronics, battery-operated devices and other equipment requiring high efficiency.    

IntroductionThe application of communication power source centralized monitoring technology in communication power supply indicates that the maintenance and management of communication power supply is changing from manual management mode to machine mode. The following is its purposes: (1) adapt to the development of communication technology; improve the maintenance and management of communication power supply equipment.(2)improve the power supply quality of communication power supply, making the power supply system have higher reliability and economy.(3) take full advantage of the computer technology to make the management of power supply equipment more automatic and intelligent.(4) realize less manual work of communication power supply equipment monitoring.(5) improve the maintenance efficiency and reduce maintenance costs. At present, the development of communication power centralized monitoring technology and the implementation of the monitoring system have entered a new era.As for function, in order to meet the requirement of machine monitoring than manual work, it emphasizes the quick response and fault alarm accuracy to the fault events of the power equipment. At present, the power supply monitoring system is continuously improved and developed based on its basic functions, such as telecontrol, teleindication and telemetering, monitoring information query, data storage and recording, real-time historical trend, system configuration, remote operation, password management, support for networking, etc. 1. Intelligent Device AccessBecause there are many kinds of communication power supply equipment, for intelligent equipment, even the same kind of equipment also have different protocols because of different manufacturers, in addition, there are many suppliers of power supply equipment, thus there are more kinds of protocols. In the process of implementation of the monitoring system, to make better use of the resources of intelligent equipment, the intelligent device is directly connected to its monitoring system through the conversion of the communication interface and protocol. The communication interface conversion basically belongs to the hardware conversion between RS-232, RS-485 and CAN, which is easy to realize. In the past, the conversion of communication protocols has always been a thorny problem in the implementation of monitoring systems. At present, this problem has been preliminarily resolved. On the one hand, most power supply equipment manufacturers can provide the communication protocol of their equipment actively, on the other hand, the intelligent equipment receives agreement officially. Both of them make the protocol conversion easily. At present, if the protocol and communication interface conversion is based on protocol converter, this method is connecting a protocol converter between an intelligent device and station monitoring host. One end is connected with the serial port of the intelligent device, another is connected with the serial port of the station monitoring host computer, thus the conversion of communication protocol and the communication interface is completed.In short, the protocol converter is a microcomputer system with CPU, EPROM, RAM, serial communication port and so on. The protocol conversion generally has two conditions: firstly, there are at least two serial ports which match with the serial ports of the converted intelligent device and the local station monitoring sovereignty respectively; secondly, the conversion software is solidified in the EPROM of the protocol conversion when the communication protocol of the intelligent device is converted into the host protocol of the local station monitoring. This method is more effective for multiple intelligent devices with different protocols connected to one monitoring host at the same time. Another way is putting the protocol conversion function in the station monitoring host, this method is not often used in practice because it is only suitable for connecting intelligent devices with a single subject protocol to a monitoring host. If there are too many kinds of protocols in a monitoring host, the monitoring host will be overburdened and its normal work will be affected. At the same time, it will bring about problems for the development of to monitoring host software. In addition, the unified communication protocol provides a better solution for intelligent device access. 2. Reliability of the Monitoring SystemAs a result of new-technology and high-quality devices are more widely used in the production of communication power supply equipment, the reliability and automation of the monitoring system have been greatly improved. For example, switching power supply equipment, UPS, diesel generator sets and other intelligent devices, as well as non-intelligent devices such as VRLA storage batteries which are widely used now. All have high reliability to improve the monitoring management and provide better conditions for the purpose of less manual work. Therefore, based on the continuous improvement of the performance of the power supply monitoring system, the reliability of the monitoring system should be improved. 3. Perfecting the Self-checking Function of the Monitoring SystemIn order to make the monitoring system play its role more effectively, it is necessary to continuously improve the basic functions of the monitoring system, meanwhile, pay attention to the use of the advantages of computer data processing, developing and improving the high intelligent performance. Fundamentally change the traditional maintenance mode, using the monitoring technology effectively.The implementation of the monitoring system is based on the new maintenance mode. That is, taking the region as the monitoring management center to monitor and manage the corresponding stations and stations. Urban monitoring and management center unifies its regions and manages them. The difference between the manual and mechanized management modes except for the maintenance, the greater difference is computer realize the automatically real-time monitoring. For example, when the power supply equipment fails, The monitoring system will make a quick response and timely report to the corresponding management center. To adapt to this kind of computer monitoring and management mode, it is necessary to change the traditional maintenance mode fundamentally. Using the computer monitoring system, which is characterized by the real-time monitoring of the power supply equipment, but it requires to read the meter at intervals within the period of time, which is stored and printed in the form of a daily report form. These statements should also be kept for two to three years. This method takes up the large resources of the monitoring system, and the data is rarely used in practice. In the face of these problems, the monitoring system in certain functions should be reconsidered:(1) On the basis of continuously improving the reliability of the controlled equipment (power supply equipment), the safety and reliability of the monitoring system can be improved comprehensively.(2) From the overall consideration of the controlled equipment and the monitoring system, since the security and reliability of the power supply equipment can be basically guaranteed (the reliability requirements of power supply equipment are: switching rectifier MTBF> 50,000h, VRLA battery MTBF> 350,000h. the reliability index of AC/DC distribution equipment is higher as required, and the reliability index of the monitoring system should be MTBF> 100000h), the implementation of the monitoring system should be simplified, practical and highly intelligent. At the same time, it should ensure the accuracy and rapidity of the alarm and warning performance of the monitoring system, also with the intelligent optimization of statistical analysis. The continuous improvement of the function makes the reading meter within time period become less significant.(3) renew the traditional maintenance concept and establish a new maintenance system.Therefore, another important task of the future monitoring system is to fundamentally change the traditional maintenance mode. Making more effective use of monitoring technology to impel the power monitoring system play a greater role in the management of communication power supply maintenance. 4. Network Access Detection of the Monitoring SystemTesting the monitoring system is difficult and will be limited by the following conditions:(1) to carry out the inspection of the monitoring system, it is necessary to have a standard basis for the items, indicators, conditions, and methods. And there are some technical requirements of the monitoring system at present, but as the standard basis of monitoring system detection is far from enough.(2) compared with the general power supply equipment, the monitoring system adopts more computer technology, and emphasizes the network and function of the system, and the real time of the system software, so it is difficult to evaluate the technical performance of monitoring system.(3) A monitoring system is a large real-time network system, which has certain capacity features (including software and hardware capacity). The realization of various performance indicators is meaningful only when the capacity is full, but it is impossible to establish a full capacity system when having these detecting indices.(4) restricted by the mode of communication, communication conditions and other aspects. ConclusionFrom the above situation, we can see that the implementation of the monitoring system is indeed facing great difficulties. Even that, the monitoring system is tested through certain methods to reach the maximum approximation. It is necessary and meaningful to describe and evaluate the performance index of the monitoring system.You May Also LikeList of Basic Electronic ComponentsSwitching Power Supply Tutorial: 4V～16VWhat is A MCU’s internal Structure: Single Chip Micro-ComputerPCB Wring Tutorial: A/D converterDIY Community: Let's Make MonitoringHydroponic Grenhouse Monitoring and Control System

The circuit that converts analog signals into digital signals is called analog-to-digital converter (abbreviated as a/d converter or adc, analog to digital converter). The function of A/D conversion is to convert time-continuous and continuous-amplitude analog quantities It is converted into a digital signal with discrete time and discrete amplitude. Therefore, A/D conversion generally involves four processes: sampling, holding, quantization, and encoding. In actual circuits, some of these processes are combined. For example, sampling and holding, quantization and coding are often implemented simultaneously during the conversion process. A short video introducing a/d converter: Electronic Basics: ADC (Analog to Digital Converter)    Catalog   I What is A/D converter? II Wiring Layout of Successive   Approximation A/D Converter III Wiring Layout of High-precision ∑-△   A/D Converter IV Conclusion FAQ   I What is A/D converter? The process of converting analog to digital is called the analog-to-digital converter, and the circuit that completes the conversion is called the A/D converter (abbreviate  ADC). Its function is making the analog signal whose time and amplitude are continuously converted to discrete digital signal whose time and amplitude are also discrete.  Fig. 1 Basic operation of an A/D converter The conversion accuracy of monolithic integrated A/D converters is described by resolution and conversion errors, and the layout of A/D converter is also changing as the conversion accuracy of AD converters increases. Specifically, the resolution rate of A/D converter refers to the number of discrete digital signals that can be output for analog signals within the allowable range, and the conversion error is usually given in the form of the maximum output error. In general, it represents the difference between the actual output of the A/D converter and the theoretical output. The multiples of the lowest significant bits are commonly represented it. For example, the relative error between −1/2 LSB and +1/2 LSB, shows that the error between the actual output digital quantity and the theoretical output digital quantity should be less than half a word of the lowest bit. Fig. 2 Relationship between analog input and digital output   At first, A/D converters originated in the analog paradigm, in which most of the physical silicon was analog. With the development of new design topology, this paradigm has evolved into a digital component as the main part in low-speed A/D converters. Although the leading role of the A/D converter change from analogue to digital, the wiring criterion of it has not changed. When cabling designers design mixed-signal circuits, basic wiring knowledge is still needed to achieve efficient wiring. In this paper, we take the successive approximation A/D converters and ∑-type A/D converters as examples to discuss the PCB routing strategy for the A/D converters.  Fig. 3  An 8-level ADC coding scheme   II Wiring Layout of Successive Approximation A/D Converter The successive approximation A/D converters have 8-bit, 10-bit, 12-bit, 16-bit, and 18-bit resolution. Initially, the process and structure of these converters were bipolar with R-2R trapezoidal resistor networks. However, these devices have been transferred to the CMOS process by using the capacitance-charge distribution topology recently. But this migration does not change the system routing strategy of these converters. Except for high resolution devices, the basic wiring methods are consistent. For these devices, special care is needed to prevent digital feedback from converter serial or parallel output interfaces. From the point of view of circuits and on-chip resources dedicated to different fields, analog plays a dominant role in successive approximation A/D converters. Fig. 4 is a block diagram of a 12-bit CMOS successive approximation A/D converter. Fig. 4 Block diagram of a 12-bit CMOS successive approximation A/D converter This converter uses the charge distribution formed by the capacitor array. In this block diagram, most of the sample/hold, comparator, digital-to-analog converter (DAC) and 12-bit successive approximation A/D converter are simulated. The rest of the circuit is digital. Therefore, most of the energy and current needed for this converter are used in internal analog circuits. This device requires very small digital current, only D/A converters and digital interfaces will have a small amount of switch-on and off. In addition, these types of converters can have multiple ground and power connection pins. The names of pin are often misunderstood because pin labels used to distinguish analog and digital connections. These labels are not intended to describe system connections to PCB, but to determine how digital and analog currents flow out of the chip. Knowing that this information and main resources consumed in the chip are analog, you will understand the significance of connecting the power supply and the ground pin on the same plane, such as the analog plane. Fig. 5 The successive approximation A/D converter, regardless of its resolution, usually has at least two connecting ends: AGND and DGND. Take Microchip's A/D converters, MCP3201 and MCP3008, as the examples in this article. Fig. 5 Pin configurations for typical 10-bit and 12-bit converters More details about these devices, two grounding pins are usually pulled out of the chip: AGND and DGND. The power supply has one lead, when using these chips for PCB wiring, AGND and DGND should be connected to the analog ground plane. And the analog and digital power pins should also be connected to the analog power plane or at least to the analog power rail, in general, every power pin is connected closely to an appropriate bypass capacitor as close as possible. But the devices such as MCP3201 have only one ground pin and one positive power pin, the only reason for this is due to the limitation of the number of packaged pins. However, isolating the grounding can improve the converter's performance and the repeatable accuracy. For the power strategy of all these converters, the analog plane should connect all ground, positive and negative power pins. Also, a “COM” pin or an “IN” pin associated with an input signal should be connected as close to the signal grounding as possible. For higher-resolution successive approximation A/D converters (16-bit and 18-bit converters), separate digital noise from "quiet" analog converters and power supply planes requires additional attention. So external digital buffers should be used for noise-free operation when these devices are interfaced with single-chip computers. Although these types of successive approximation A/D converters usually have internal double buffers on the digital output side, external buffers are still needed to further isolate the analog circuits in the converters from the digital bus noise.  Fig. 6 Correct power policy for this system   For high-resolution successive approximation A/D converters, the power and grounding of the converter should be connected to the analog plane. Then, the digital output of the A/D converter should be buffered with external tristate output buffers. These buffers have the function of isolating the analog and digital sides in addition to the high-drive capability.   Fig. 7 Layout block diagram of successive approximation A/D converter   III Wiring Layout of High-precision ∑-△ A/D Converter Fig. 8  Schematic diagram of high-precision ∑-△ type A/D converter The main part of a silicon board in high precision ∑-△ type A /D converter is digital. In the early stage of converter production, the shift in the example prompted users to use PCB planes to isolate digital and analog noise. Like successive approximation A/D converters, these types of A/D converters may have multiple analog grounding, digital grounding, and power pins. Digital or analog design engineers tend to separate the pins and connect them to different planes. However, this is wrong, especially if you try to solve the serious noise problem of 16-bit to 24-bit precision devices. For a high-resolution ∑-△ type A/D converter with 10Hz data rate, the clock (internal or external) added to the converter may be 10MHz or 20MHz. This high-frequency clock is used for switching modulators and over-sampling engines. For these circuits, the AGND and DGND pins are connected on the same ground plane as the successive approximation A/D converters. Also, analog and digital power pins are best connected on the same plane. The requirement of analog and digital power plane is the same as that of high-resolution successive approximation A/D converter. There must be a ground plane, which means that at least two panels are required. On this double panel, the ground plane should cover at least 75% of the total panel area. The purpose of the ground plane layer is to reduce the grounding impedance and inductance, and to provide shielding that against electromagnetic interference (EMI) and radio frequency interference (RFI). If an internal connection line is required on the ground plane side of the circuit board, the line should be as short as possible and perpendicular to the earth current loop. IV Conclusion For low-precision A/D converters, such as six-bit, eight-bit or maybe even 10-bit A/D converters, the analog and digital pins are not separated. But when the converter accuracy and resolution of the selected converters increase, wiring requirements become more stringent. High-resolution successive approximation A/D converters and ∑-△ type A/D converters need to be directly connected to low-noise analog ground and power plane.   FAQ   1. How does an AD converter work? Analog-to-Digital converters (ADC) translate analog signals, real world signals like temperature, pressure, voltage, current, distance, or light intensity, into a digital representation of that signal. This digital representation can then be processed, manipulated, computed, transmitted or stored.   2. What are ad DA converters used for? DACs are commonly used in music players to convert digital data streams into analog audio signals. They are also used in televisions and mobile phones to convert digital video data into analog video signals. These two applications use DACs at opposite ends of the frequency/resolution trade-off.   3. What is the main role of an ADC? In more practical terms, an ADC converts an analog input, such as a microphone collecting sound, into a digital signal. An ADC performs this conversion by some form of quantization – mapping the continuous set of values to a smaller (countable) set of values, often by rounding.   4. What is the difference between AD and DA converters? A D/A converter takes a precise number (most commonly a fixed-point binary number) and converts it into a physical quantity (example: voltage or pressure). ... An ideal D/A converter takes abstract numbers from a sequence of impulses that are then processed by using a form of interpolation to fill in data between impulses.   5. Why is a DAC needed? Any time you want to listen to a digital audio signal (like an MP3 or the audio from a digital video) through an analog output (like wired headphones and speakers), you need a DAC to convert the digital signal from the source into an analog signal at the point of connection. ... This is why you need a separate DAC.   6. How are AD converters categorized? Main Types of ADC Converters. Successive Approximation (SAR) ADC. Delta-sigma (ΔΣ) ADC. Dual Slope ADC. Pipelined ADC.   7. Which is fastest ADC? flash ADC. The flash ADC is the fastest type available. A flash ADC uses comparators, one per voltage step, and a string of resistors. A 4-bit ADC will have 16 comparators, an 8-bit ADC will have 256 comparators.   8. What is better analog or digital signal? The smooth analog signal matches the recorded sound wave better than the steps of a digital recording. However, the analog medium (vinyl or magnetized tape) the recording is imprinted on can have tiny imperfections that cause cracking and popping noise.   9. Why are ADC and DAC required in an embedded system? An embedded system uses the ADC to collect information about the external world (data acquisition system.) The input signal is usually an analog voltage, and the output is a binary number.   10. Why ADC is used in microcontroller? An analog-to-digital converter (ADC) is used to convert an analog signal such as voltage to a digital form so that it can be read and processed by a microcontroller. Most microcontrollers nowadays have built-in ADC converters. It is also possible to connect an external ADC converter to any type of microcontroller.  

This article would introduce MCU in details, including analysis its internal structure, and elaborate some important concepts, especially would put emphasis on the concept of memory decoding.   Catalog I. What is MCU? II. Some Basic Concepts 2.1 The Meaning of Rom 2.2 The Meaning of Bit 2.3 The Meaning of Bytes III. The Working Principle of Memory IV. MCU Circuit v. Memory Decoding FAQ   I. What is MCU?   MCU(microcomputer) is an integrated circuit chip. It integrates the microprocessor(CPU), which has data-handling technology such as arithmetic, logic and data transfer, etc, random access data memory(RAM), read-only program memory(ROM), input and output circuit (I/O port) that using the very large scale processing-data technology and may also include a timing counter, serial communication port (SCI), display drive circuit (LCD or LED drive circuit), pulse width modulation circuit (PWM), analog multiplexer and A/D converter, which form a minimum but perfect computer system.   Under the control of software, these circuits can complete the tasks specified by the program designer accurately, quickly, and efficiently. From this point of view, the single-chip microcomputer has the function which the microprocessor does not have, it has intelligent control functions which the modern industry control request separately. And this is the single-chip microcomputer's biggest characteristic.       II. Some Basic Concepts   2.1 The Meaning of Rom Let's think about a problem: when we write instruction in a programmer into an MCU and then take off it, the MCU can execute the instruction, so the instruction must be stored somewhere in the MCU. And this place can still maintain this instruction not to be lost after it power-off. What place is this? This place is the internal ROM of MCU, which is the read-only program memory. Why do you call it read-only memory? We use the programmer, external equipment, to write to the ROM operation under special conditions. In the MCU normal working conditions,  the data can only read but can’t write in, so we call it ROM.   2.2 The Meaning of Bit From the experiment above, we already know that the level of a lamp or a line can represent two states: 0 and 1. In fact, this is a binary bit, thus we call a line a bit, expressed in BIT.   2.3 The Meaning of Bytes A line can represent 0 and 1, two lines can express 00, 01, 10, 11 four states, that is, it can express 0 to 3, and three can express 0 to 7. The computer usually put with eight lines together, counting at the same time, can represent 0 to 255, for a count of 256 states. These eight lines or 8-bit is called a byte (BYTE).   III. The Working Principle of Memory   Structure All the instructions that a single-chip microcomputer can execute are the instructional systems of it. Different kinds of single-chip computers have different instructional systems. In order for a single-chip microcomputer to automatically complete a specific task, the problems to be solved must be programmed into a series of instructions (these instructions must be recognized and executed by the selected single-chip microcomputer). These instructions integrated into the program, and the program needs to be stored in memory—a storage unit.    The memory consists of many storage units (the smallest unit of storage), just as a building has many rooms, each room in a large building is assigned a unique room number. Each storage unit must also be assigned a unique address number, which is known as the address of the storage unit so that the address of the storage cell is known. The instructions are stored in these units. The storage unit can be found, where the stored instructions can be taken out and then executed.   Memory is the place where data is stored. It uses the electricity level to store the data, that is, it actually stores the electrical level, not the number of 1234 that we are used to thinking of. A memory is like a small drawer. If there are eight small drawers in a small drawer, each one is used to store the "charge," and the charge is passed in or released through the wire attached to it. You can think of a wire as a pipe, and the charge in the grid is like water, so it's easy to understand it. Each small drawer in memory is a place for data, which we call a ''bit''.   With this structure, we can start storing data. If we want to put in a data 12, that is 00001100, and we just have to fill the second and third squares with the charge, and the other cells are free of the charges. But the problem is that memory has a lot of cells, and the lines are parallel, and when you put the charge in it, you put the charge in all the cells, and when you release the charge, you release the charge from each cell. In the case of it, no matter how many cells the memory has, it can only be put in the same number, which is certainly not what we want.    A little bit to change structurally,  there's a control line on each unit, and if you want to put the data in the unit, give a signal to the control line of the unit. Therefore, the control line turns on the switch so that the charge can flow freely. And there is no signal on the other unit control lines, so the switch turns off and will not be affected, so that if you handle the control lines of different units, you can write different data to each unit. Similarly, if you want to take data from one unit, just turn on the corresponding control switch.     IV. MCU Circuit   A circuit is always made up of components connected by wires. In analog circuits, wiring is not a problem, because there is usually a serial relationship between the devices, and there are not many connections between the devices, but the computer circuits are different. The microprocessor is the core for it, each device must be connected to the microprocessor, the work of each device must be coordinated, so it needs a lot of connections.   If still like analog circuits, there will be an amazing number of lines between microprocessors and devices, so the concept of a bus has been introduced into the microprocessor, and each device has shared the connection. All 8 data lines are connected to eight common lines, that is, the equivalent of each device is in parallel, but this is not enough. If there are two devices delivering data at the same time, one is 0 and the other is 1, what exactly does the receiver get? This situation is not allowed, so control through the control line to make the device working time-sharing, at any time there can be only one device to send data ( multiple devices can receive at the same time).      V. Memory Decoding   So how do we control the control lines of each unit? It is not that simple to lead the control lines of each unit out of the integrated circuit. There are 65,536 units in a model 27512 memory, and if each line is drawn out, the integrated circuit must have more than 60,000 feet, so it is necessary to find a way to reduce the number of lines. We have a way called decoding, briefly introduce: one line can represent two states and two lines can represent four states and three lines can represent eight kinds, and so on, thus we only need 16 lines to represent 65536 states.   Since the decoding problem solved, let's focus on another problem. Where did the eight lines in each unit come from? Actually, it is connected to the computer, in general, the eight wires not only for memory but also connected to other devices. The problem arises in this way. Because these eight wires are not dedicated to the memory and the computer, it is not good if a unit is always connected to the eight wires. For example, if the value in this memory cell is 0FFH but there one unit is OOH, then what the line set at a high level or a low level?   Thus we have to separate them. The solution is: when the outside wire is connected to the pin of the integrated circuit, it does not directly attach to the units, but a set of switches is added to the middle. Normally we leave the switch off, and if we really want to write data to this memory, or read the data out of the memory, just turn the switch on. This set of switches is selected by three leads: read control, write control, and chip selector.    To write data into the chip, select the chip first, then send a write signal, the switch turns on, and the incoming data (charge) is written into the film chip. If you want to read, select the film chip first, and then send out the read signal, the switch turns on, and the data is sent out. The read and write signals are also connected to another memory at the same time, but the chip selector ends are different.   Although there is a read or write signal, there is no chip selection signal, so the other memory will not "misunderstand" and result in a conflict. What will happen if you pick two chips at the same time? Actually, this can’t be happening because the system is designed and controlled by computer, not by the human. If any, there’s something wrong with the circuit.     From the introduction above, we have seen that the eight lines used to transmit data are not dedicated, but shared by many devices, so we call it data bus. The data line of the device is called the data bus, and all the control lines of the device are called the control bus. There are memory cells in the internal or external memory and other devices of a single chip. Units must be assigned addresses before they can be used. Of course, the assigned addresses are also given in the form of electrical signals. Because there are too many memory cells, there are many lines for address allocation, which are called address buses. Sixteen address lines are also connected, called address buses.   FAQ   1. What are the characteristics of microcomputer? a. Small size and low cost. b. One user. c. Easy to use. d. Low computing power. e. Commonly used for personal application.   2. What are the advantages of microcomputer? a. This computer is widely used today. b. The microcomputer is small in size. c. The microcomputer is used to design different software and app. d. This type of computer is a low cost, so all the users can easily buy. e. No need for highly trained staff for operating microcomputer to office work.   3. Why microcontrollers are often called single chip computers? Single-chip computers are mainly of the form known as Microcontroller chips (the most commonly known are the PIC range by Microchip inc) and used in embedded devices. They provide much more basic functionality but are far simpler to work with as they don't require any external chips in order to function.   4. What is single chip microcomputer that has everything inbuilt? This is a microcomputer built using separate components (CPU, Memory, etc.). ... For some specific applications, we also have single chip computers in a VLSI chip. This single chip microcomputer will have a CPU, memory and I/O interfaces, timers, ADC/DACs etc. on a single chip itself.   5. What is difference between microprocessor and microcomputer? The main difference between Microprocessor and Microcomputer is that the Microprocessor is a computer processor contained on an integrated-circuit chip and Microcomputer is a small, relatively inexpensive computer. ... Microprocessors contain both combinational logic and sequential digital logic.   6. Is Raspberry Pi a microcomputer? The Raspberry PI is a microcomputer that's often used by hobbyists to create projects like animated LED displays or bird watchers.   7. Which is a feature of a single chip microcomputer? A single-chip microcomputer is a major branch of a microcomputer. The biggest feature of the structure is that the CPU, memory, timer and various input/output interface circuits are integrated on a very large-scale integrated circuit chip. In terms of its composition and function, a single chip is a computer.   8. What are the components of microcomputer? The main components are: (1) the central processing unit (CPU), (2) input devices, (3) output devices, and (4) memory. The CPU of a microcomputer performs all the arithmetic, logic, and data handling functions of the microcomputer.   9. Is microcontroller a microcomputer? A Microcontroller is a small and low-cost microcomputer, which is designed to perform the specific tasks of embedded systems like displaying microwave information, receiving remote signals etc.   10. What is the definition of microcomputer? Microcomputer, an electronic device with a microprocessor as its central processing unit (CPU). Microcomputer was formerly a commonly used term for personal computers, particularly any of a class of small digital computers whose CPU is contained on a single integrated semiconductor chip.   You May Also Like Transformers Basics: Construction, Types, Materials and Design Switched Mode Power Supply Tutorial: Principles & Functions of SMPS Circuits List of Basic Electronic Components Switching Power Supply Tutorial: 4V～16V