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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

In the design of circuit systems, we often encounter things like this: when a circuit program is copied from the book completely, the result of the experiment is not correct. Why is it that? The reason is interference. We must do a good job of anti-interference in the process of the electronic circuit and program design.     Catalog I. Three Basic Element of Interference II. Suppressing Interference Sources     2.1 Common Measures to Suppress Interference Sources     2.2 Common Measures to Cut off the Path of Interference Propagation     2.3 Improve the Anti-interference Performance of Sensitive Devices III. Experience and Advice FAQ   I. Three Basic Element of Interference   a. Interference Source: Refers to the components, devices, or signals that cause interference, as described in mathematical terms as follows: some places where the figure of du/dt(voltage regulator factor) or di/dt(current rate of charge) is large may be the interference source. Also the lightning, relays, SCR, motor, high-frequency clock and so on may become interference sources.   b. Propagation Path: Refers to A path or medium in which interference travels from an interference source to a sensitive device. The typical path of interference propagation is the conduction of wires and the radiation of space.    c. Sensitive Device: Refers to an object that is susceptible to interference. Such as A/D or D/A converter, single-chip microcomputer, digital IC, weak signal, and so on. The basic principle of anti-jamming design is to suppress the interference source, cut off the path of interference propagation, and improve the anti-jamming performance of sensitive devices.   II. Suppressing Interference Sources   Suppressing interference sources is to minimize the du/dt and di/dt of interference sources as much as possible. Reduce the du/dt of the interference source by paralleling capacitors at both ends of the interference source; reduce the di/dt of the interference source by using the series inductance or resistance in the interference source loop and adding the freewheel diode. This is the highest priority and the most important principle in anti-interference design.   2.1 Common Measures to Suppress Interference Sources are as follows: (1) Add freewheel diode to the relay coil to eliminate the interference when disconnecting the coil. Only having a freewheel diode will delay the break time of the relay, therefore adding an extra more Zener diode will increase the number of operating times of the relay in unit time.   (2) Connect spark suppression circuit at both ends of relay contact(is usually RC; resistor is selected from several kΩ to dozens of kΩ; capacitance selects 0.01uF), so as to reduce the interference.   (3) Add filter circuit to the motor, pay attention to the capacitance, and inductance lead should be as short as possible.   (4) each IC on the circuit board should be connected with a high-frequency capacitor of 0.01 μ F to 0.1 μ F to reduce the influence of IC to the power supply. Pay attention to the wiring of high-frequency capacitance. The connection should be close to the power supply and should be as short as possible. Otherwise, it will increase the equivalent series resistance of the capacitance, which will affect the filtering effect.   (5) Avoid 90 degree fold line and reduce high-frequency noise when wiring.   (6) Connect the RC suppression circuit to both ends of the thyristor to reduce the noise caused by the thyristor (ps: if the noise is serious may break down the thyristor).   According to the path of interference, it can be divided into two types: conduction interference and radiation interference. Conduction interference is the interference that propagates through the wire to the sensitive device. The high-frequency interference noise is different from the useful signal in the frequency band, which can be cut off by adding a filter to the conductor, and sometimes it can be solved by isolating the optical coupling. Power noise is the most harmful, we should pay special attention to handling. Radiation interference refers to the interference which propagates through the space radiation to the sensitive device. The general solution is to increase the distance between the interference sources and the sensitive devices, to isolate them with grounding wires, and mask the sensitive devices.     2.2 Common Measures to Cut off the Path of Interference Propagation (1) Consider the influence of power supply on single-chip computers. A good power supply helps solve the majority of the jamming problems in circuit design. Many single-chip computers are sensitive to the noise of the power supply, so it is necessary to add a filter circuit or voltage stabilizer to the power supply of a single-chip microcomputer to reduce the interference. For example, a π-shaped filter circuit composed of magnetic beads and capacitors, in addition, a 100Ω resistor can be used to replace magnetic beads when the conditions are not high.   (2) If the I/O port of the single-chip microcomputer is used to control the noise devices such as motors, the I/O port, and the noise source should be isolated.（ adding a π-shaped filter circuit）   (3) Pay attention to the crystal wiring. The crystal oscillator and single-chip microcomputer pin should as close as possible; the clock area should be isolated by grounding wire, crystal oscillator shell should be grounded and fixed. This measure can solve many difficult problems.   (4) Make reasonable partitions of the circuit board. Such as strong signal and weak signal, digital signal, and analog signal. Interference sources (such as motors and relays) and sensitive elements (such as microcontroller) should be isolated as far as possible.   (5) Separate the digital area from the analog area by landlines, and finally, connect to the power at one point. This principle is taken into account when the manufacturer makes the A/D and D/A chip pins arrangement.   (6) Single-chip microcomputer and large ground wire should be grounded separately to reduce mutual interference. High-power devices should be placed on the edge of the circuit board as far as possible.   (7) Use the anti-interference components such as magnetic beads, magnetic rings, power filters, and shielding covers in key places such as I / O portion, power lines, and circuit board connectors, which can significantly improve the anti-interference performance of the circuit.   2.3 Improve the Anti-interference Performance of Sensitive Devices To improve the anti-jamming performance of sensitive devices is to reduce the picking up of interference noise from the interference sources and to recover from abnormal state as soon as possible. The Usual Measures are as Follows: (1) Reduce the area of the loop in order to reduce the inductive noise.   (2) Power and ground wires should be as thick as possible, besides reducing the pressure drop, it is more important to reduce the coupling noise.   (3) The idle I / O port of SCM shouldn’t suspend, but connecting the ground or power supply. And the idle ends of other IC should be grounded or connected to power without changing the logic of the system.   (4) Using the power source monitoring and watchdog timer, such as IMP809, IMP706, IMP813, X25043, X25045, and so on, can greatly improve the anti-interference performance of the whole circuit.   (5) Under the condition that the speed can meet the requirement, the crystal oscillator of the single chip microcomputer is reduced and the low-speed digital circuit is chosen as far as possible.   (6) IC device is welded directly to the circuit board as far as possible.   III. Experience and Advice Software 1. Clearing the code space that is not commonly used, because this is equivalent to the NOP, can help programs recover when appearing program fleet.   2. Adding several NOP before the jump instruction, the same purpose as 1.   3. When there is no hardware WatchDog, an analog one can be used through software to monitor the operation of the program.   4. Dealing with the adjustment or setting of external device parameters, the parameters can be re-transmitted periodically in order to prevent the external device from making mistakes due to interference, so that the external device can be restored correctly as soon as possible.   5. Adding additive data to check anti-interference in Communication.   6. When there are communication lines, such as I2C or a three-wire system, it is found that the anti-interference effect of the Data line is better than that of the low one.   Hardware 1. The layout of grounding and power supply wires.   2. The decoupling of the circuit.   3. The separation of digital ground wire and analog ground wire.   4. Each digital element needs 104 capacitors between the grounding and the power supply.   5. In the applications with relays, especially in the case of high current, a 104 and diode can be combined between the relay coils to prevent the contact spark interference of the relay, and 472 capacitors installed at the contact point and the normal beginning.   6. To prevent the crosstalk of I / O port, the I / O port can be isolated by diode isolation, gate isolation, optocouple isolation, electromagnetic isolation, and so on.   7. Multi-layer board anti-jamming is certainly better than single-layer board, but its cost is several times higher.   8. Choosing an anti-jamming device is more effective than any other method.   FAQ   1. What is Circuit interference? Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.   2. What causes electrical interference? What Causes Interference? Interference occurs when undesired radio signals or electromagnetic "noise" sources are picked up by consumer electronics products -most often telephones, audio equipment, VCRs or TVs. It usually results in noise, unwanted voices or distorted TV pictures. In most cases, the source is nearby.   3. What is meant by circuit design? As circuit design is the process of working out the physical form that an electronic circuit will take, the result of the circuit design process is the instructions on how to construct the physical electronic circuit.   4. What is circuit design theory? In integrated circuit design automation, the term "circuit design" often refers to the step of the design cycle which outputs the schematics of the integrated circuit. Typically this is the step between logic design and physical design.   5. Which software is best for circuit design? a. Eagle b. Altium c. Proteus d. KiCad e. Cadence OrCAD PCB Designer f. DesignSpark g. Protel h. Cadstar i. Sprint-Layout j. PADS PCB   6. How does circuit design work? Digital electronic circuit design takes the electrical signals in the form of discrete values. The data are represented in the form of zeros and ones. Digital circuits extensively use transistors, interconnected to give create logic gates that provide the function of Boolean logic.   7. How long does it take to design a circuit? Programming the Micro-controller. Division of labor will make the work more efficient and specializations and expertise are more focused. Normally, it only takes hours to program the microcontroller of a simple circuit but complex circuit diagrams may take 2 to 3 days.   8. Is circuit design difficult? Designing a circuit is easy if you the basic working principle of each & every electronics components you're going to use. But making it efficient is a bit time-consuming. Once you know the rules, it's normally not too difficult. Of course, some circuits are more difficult than others.   9. What are the types of circuit? There are 5 Main Types of Electric Circuit – Close Circuit, Open Circuit, Short Circuit, Series Circuit and Parallel Circuit.   10. What is the process of a circuit? The process of circuit design can cover systems ranging from complex electronic systems all the way down to the individual transistors within an integrated circuit. ... Typically this is the step between logic design and physical design.   You May Also Like Can We Manage to Recycle PCB Boards for Avoiding Harming the Environment? 10 Things to Consider While choosing a PCB Prototype Service Some Guides for Beginners Before You Create A Printed Circuit Board(PCB) Industrial Chain and Development Trend of PCB in China

The insulated gate bipolar transistor (hereinafter referred to as IGBT) is a composite device of MOSFET and GTR. Thus it has the advantages of MOSFET and GTR, it is an ideal switch device to replace GTR, which is widely used at present with its ability to turn off, and it’s also widely used in all kinds of solid-state power supply.     Catalog   I. What is IGBT? II. The Driving Requirement of IGBT III. The Overcurrent Protection Analysis of IGBT IV. Simulation and Experiment FAQ   I. What is IGBT?   The insulated gate bipolar transistor (hereinafter referred to as IGBT) is a composite device of MOSFET and GTR. Thus it has the advantages of MOSFET, including fast operation speed, high switching frequency, high input impedance, simple drive circuit, and good thermal temperature; it also contains the advantages of GTR, like large current-carrying capacity and high blocking voltage. It is an ideal switch device to replace GTR, which is widely used at present with its ability to turn off and is also widely used in all kinds of solid-state power supply.   And it requires a reasonable drive circuit, but its improper control may cause damage, such as IGBT damage due to overcurrent, and affects the performance of the whole machine. In a word, the drive circuit is very important to IGBT. So this paper mainly discusses the driving and short-circuit protection of IGBT, based on the analysis of its working principle, then designs and simulates the overcurrent protection of the drive circuit.     Electronic Basics #28: IGBT and when to use them     II. The Driving Requirement of IGBT   Driving Requirement IGBT is a voltage-type control device. To make IGBT turn on and off safely and reliably, the driving circuit must meet the following conditions.  And the gate capacitance of IGBT is much larger than that of MOSFET. To increase the switching speed, it is necessary to have a suitable gate bias voltage and gate series resistance.   Gate Voltage In any case, the gate drive voltage in the open state can not exceed the limited value (generally 20V) given by the parameter table, and the optimal gate forward-bias voltage is 15 V ±1.5V. This value is sufficient to allow IGBT to reach saturation and then getting conduction, which can minimize the conduction loss. In the case of gate voltage is cutting off with the value of zero, to reduce the turn-off time and improve the withstand voltage and anti-interference ability of IGBT, a reverse voltage of -5 ~ -15 V can be added between the gate and the source electrode when the IGBT is in a blocking state.   Gate Series Resistance Core The selection of appropriate gate series resistance (RG) is very important for the drive of IGBT. The effect of RG on switching loss is shown in Fig.1. Fig. 1 The Effect of RG on Switching Loss It is the dynamic current of charging and discharging the input capacitance rather than the DC current that is required in a static state, and the input impedance of IGBT is up to 109 ~ 1011. In this case, the DC gain can reach 108 ~ 109, almost without any power consumption.   To decrease the steepness of the front and rear edges of the control pulse, prevent oscillation and reduce the voltage tip pulse with a large IGBT collector, it is necessary to add a gate series resistor RG. When the RG increases, the on-off time will prolong and the energy consumption of the IGBT will increase; in turn, the RG reduces, the di/dt will increase and may damage IGBT.   Thus, according to the current capacity and voltage rating, and switching frequency of IGBT, it is necessary to select a suitable RG, usually from dozens of ohms to hundreds of ohms. To get a more specific value of RG, it is suggested to refer to the device manual. Fig.2 Main Circuit of Inverter Power Supply   Requirements for Driving Power The switching process of IGBT consumes a certain amount of power from the driving power supply. The difference between the gate forward bias voltage and the reverse bias voltage is the △VGE; working frequency is f, the gate capacitance is CGE; and the minimum peak current of the power supply is:     Overcurrent Protection for IGBT The overcurrent protection of IGBT is limiting the short-circuit current and its I-V track to the short circuit safe working area when the device overflows, and the IGBT is turned off before the device is damaged to avoid the damage of the switch tube. When the upper and lower arms conducting, the power supply voltage is almost all added to the two ends of the switch, at this time, the larger the short circuit current is, the smaller the saturation voltage drop will be, during this time, the device would be damaged due to the large current.     III. The Overcurrent Protection Analysis of IGBT   Based on the above analysis, an IGBT drive circuit which contains isolated optocoupler and over-current protection has been put forward in this article, as shown in Fig.3. Fig.3 The Drive and Overcurrent Protection Circuit of IGBT  In Fig.3, the high-speed optocoupler 6N137 realizes the electrical isolation of the input and output signals, which is suitable for high-frequency applications. The main drive circuit adopts push-pull output mode, which effectively reduces the output impedance of the drive circuit, improves the driving ability, and makes it suitable for the drive of high power IGBT.   The over-current protection circuit uses the principle of desaturation of the collector. When an over-current occurs, the IGBT will be turn off. The V1, V3and V4 constitute the driving pulse amplifier circuit; V1 and R5 constitute an emitter follower. The emitter follower provides a fast current source, which reduces the turn-off time. Using the collector desaturation principle, D1, R6, R7, and V2 form a short-circuit signal detection circuit. D1 is a fast recovery diode, to prevent the high voltage on the collector from running into the driving circuit when IGBT is turned off.   In order to prevent the power device from being misled by static electricity, bidirectional voltage regulators D3 and D4 are connected in parallel between the gate sources.   Normal When the control circuit sends a high-level signal, the optocoupler 6N137 turns on, V1, V2 turns off, V3 turns on and V4 turns off. And the drive circuit provides IGBT a driving voltage of +15V to turn it on. When the control circuit sends a low level signal, the optocoupler 6N137 turns off, V2 and V3 conduct, and the drive circuit provides a voltage of -5v to IBGT, making IGBT shut down.   Overcurrent When a short-circuit fault exists, the voltage of 15V is almost all added to the IGBT. At this time, the voltage of V2 cuts off in the short circuit detection circuit, and the electric potential of point A depends on the partial voltage of D1, R6, R7, and VCES.  When the main circuit works normally and the IGBT is on, the A point is kept low, which is lower than the B point potential. All A1 output low level, this time V5 cuts off, and the C point is high level.   So when operating normally, the input to the optocoupler 6N137 is always consistent with the output. When overcurrent occurs, the IGBT collector is desaturated, A point potential rises, when it is higher than B potential ( the setting potential), that is, when the current exceeds the designed fixed value, the A1 overturns and outputs a high level, meanwhile, V5 is switched on, thereby making C in a low potential state. The input signal to the optocoupler 6N137 is always low level regardless of whether the control circuit is sent to a high level or a low level to turn off the power tube. Thus, over-current protection is achieved until the circuit is troubleshot and then restarted.   Fig. 4 Strong Driving Circuit of IGBT with Short-Circuit Protection   IV. Simulation and Experiment   Input to the drive circuit with a high level of 15V and a low level of -5V square wave signal. The output waveform of IGBT is shown in Fig.5  Fig.5 IGBT Output Signal According to the above principle and analysis, the actual output waveform of the circuit is shown in Fig.6  Fig.6 Actual Circuit Output Waveform Conclusion (1) Providing -5V and +15V driving voltage for IGBT to ensure IGBT's turn on and off. (2) Having over-current protection to prevent the IGBT from being damaged when the current is overcurrent. (3) Using in a wide range because the circuit can dynamically adjust the maximum current according to the load. (4) Adopting discrete components as the driving circuits to reduce the cost of the whole system.     FAQ   1. How does an insulated gate bipolar transistor work? The IGBT combines the simple gate-drive characteristics of power MOSFETs with the high-current and low-saturation-voltage capability of bipolar transistors. The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device.   2. Which insulated gate bipolar transistor? IGBTs are widely used as switching devices in the inverter circuit (for DC-to-AC conversion) for driving small to large motors. IGBTs for inverter applications are used in home appliances such as air conditioners and refrigerators, industrial motors, and automotive main motor controllers to improve their efficiency.   3. How do I trigger IGBT?   An IGBT is simply switched “ON” and “OFF” by triggering and disabling its Gate terminal. A constant +Ve voltage i/p signal across the 'G' and the 'E' will retain the device in its “ON” state, while deduction of the i/p signal will cause it to turn “OFF” like BJT or MOSFET.   4. Why use an IGBT instead of a Mosfet? The main advantages of IGBT over a Power MOSFET and a BJT are: 1. It has a very low on-state voltage drop due to conductivity modulation and has superior on-state current density. So smaller chip size is possible and the cost can be reduced.   5. Why IGBT is used an inverter? The Insulated Gate Bipolar Transistor (IGBT) is used in VFD inverter modules as the preferred electronic power switch for the following reasons. ... The IGBT has a fast switching speed. This minimises switching losses and allows for high switching frequencies which is good for motor harmonic and noise reduction.   6. What is difference between IGBT and SCR? SCR is a silicon control rectifier and igbt is a insulated gate bipolar transistor. ... scr has anode ,cathode and gate and igbt has base ,emitter, gate ,and collector. In the both devices gate terminal is used for triggering. Scr has only one insultive layer but igbt has 2 insulated silicon layers.   7. What is IGBT principle? IGBT Principle of Operation：IGBT requires only a small voltage to maintain conduction in the device unlike in BJT. The IGBT is a unidirectional device, that is, it can only switch ON in the forward direction. This means current flows from the collector to the emitter unlike in MOSFETs, which are bi-directional.   8. What causes IGBT failure? The failure modes for the IGBT are in the form of degradation of certain key electrical parameters (e.g., leakage current, threshold voltage) or the loss of functionality (inability to turn-off). The failure causes can be due to environmental conditions or operating conditions.   9. Is IGBT unipolar or bipolar? The IGBT cannot conduct current in the reverse direction (from emitter to collector) even with a positive Vge applied to it, because it has a bipolar-type structure.   10. Which IGBT used in VFD? IGBT (insulated gate bipolar transistor) provides a high switching speed necessary for PWM VFD operation. IGBTs are capable of switching on and off several thousand times a second. A VFD IGBT can turn on in less than 400 nanoseconds and off in approximately 500 nanoseconds.   11. Can we use IGBT instead of Mosfet? Due to the higher usable current density of IGBTs, it can usually handle two to three times more current than a typical MOSFET it replaces. This means that a single IGBT device can replace multiple MOSFETs in parallel operation or any of the super-large single power MOSFETs that are available today.   12. How fast can an IGBT switch? The typical switching time of IGBT is about hundreds of nanoseconds and the value varies with load current, junction temperature, and other factors [17–20]. However, the change of IGBT switching time is very small [4,5] (range from several to tens of nanoseconds) when the health status of the IGBT module changes.   13. Is IGBT faster than Mosfet? When compared to the IGBT, a power MOSFET has the advantages of higher commutation speed and greater efficiency during operation at low voltages. ... The IGBT combines the simple gate-drive characteristics found in the MOSFET with the high-current and low-saturation-voltage capability of a bipolar transistor.   14. How many IGBT are in a VFD? Six IGBTs. In a typical six pulse drive there are six IGBTs pulsing voltage up to 15,000 times per second. Since their introduction in the 1980's, IGBTs have literally switched up the market and now play a large role in many modern day power electronics applications where speed and process control are needed.   15. What is the function of IGBT? The IGBT combines, in a single device, a control input with a MOS structure and a bipolar power transistor that acts as an output switch. IGBTs are suitable for high-voltage, high-current applications. They are designed to drive high-power applications with a low-power input.   16. Is IGBT a rectifier? IGBTs have a pretty good current handling capacity when compared to standard BJTs (Bipolar junction transistor) and MOSFETs (metal–oxide–silicon transistor). IGBTs are devices whose switching is fully controlled electronically. Most standard rectifiers in the market are typically 6-pulse rectifiers.   17. How many types of IGBT are there? two types. The IGBT is classified as two types based on the n+ buffer layer, the IGBTs that are having the n+ buffer layer is called the Punch through IGBT (PT-IGBT), the IGBTs that does not have an n+ buffer layer are called the Non-Punch Through- IGBT (NPT- IGBT).   18. How do you prevent IGBT failure? IGBT turn-off requires that the IGBT be driven to the cutoff region of operation so that it can successfully block the reverse high voltage across it once the high-side IGBT has turned on. In principle this can be achieved by reducing the IGBT gate-emitter voltage to 0 V.   19. What is the difference between unipolar and bipolar devices? As their name implies, Bipolar Transistors are “Bipolar” devices because they operate with both types of charge carriers, Holes and Electrons. The Field Effect Transistor on the other hand is a “Unipolar” device that depends only on the conduction of electrons (N-channel) or holes (P-channel).   20. What is IGBT and Igct? GTO stands for Gate Turn-Off Thyristor, IGCT stands for Insulated Gate Commutated Thyristor and IGBT stands for Insulated Gate Bipolar Transistor. The comparison between the three devices are derived with respect to symbol, characteristic, advantages, disadvantages and applications.   You May Also Like The First Fully 2D FETs Lead A Faster Electronic Future The First Printed 2D Transistor Is Discovered by Researchers The First Chemical Circuit Developed Smarter transistors could be three times more efficient

Regarding the design of a micropower isolated power supply for the two-wire transmitter, we must know what is the transmitter first. When the output of the sensor is a specified standard signal, it is called a transmitter. A sensor, usually composed of sensitive elements and conversion elements, is a floorboard for a component or device that can be measured and converted into a usable output signal according to certain rules. And the common types are power transmitters, current-voltage transmitters, and so on.How to Build a FM Radio Transmitter CatalogI. Brief Introduction to Internal Micro-power Supply DesignII. Overall DesignIII. Constant Current Voltage Stabilizing CircuitIV. DC/CD in CircuitV. Isolated Power Source WindingVI. ConclusionFAQ I. Brief Introduction to Internal Micro-power Supply Design The design of an internal micro-power supply is very important when developing a low-power intelligent two-wire transmitter. Firstly, in order to satisfy the power supply of the micro-controller, A/D, D/A, and communication circuit, the intelligent transmitter with microprocessor needs more power than that of an ordinary 4~20mA one), and its power supply efficiency of the internal power supply must be higher.  In addition, for capacitive sensors and thermocouples, it is necessary to consider the case of grounding or the possibility of the sensor earthing. So the input and output of the designed transmitter circuit must be isolated, only this way can guarantee the normal operation of the follow-up control system and the ability of anti-common-mode interference.  Since the external circuit provides the maximum working current of 4mA for the two-wire transmitter system, specific requirements like this bring great difficulties and challenges to the design of the power supply of the system. Adopting a full integrated circuit, the isolated two-wire transmitter power supply with micro-input power has the advantages of simple structure, stable performance, and low cost. And it takes the 12~35V DC as the input power, designing the simple input circuit of the constant current and stable voltage front end, fixing the consumption of 315mA current, and providing two sets of isolated 3V power supply. In this case, the not isolated imputing group with maximum 5mA load capacity and the isolated imputing group with maximum 3mA load capacity, which can meet the requirements of input and output isolating two-wire transmitters for power supply.  II. Overall Design Fig.1 is a schematic diagram of the power supply. It consists of three main parts: 315mA/812V constant current voltage stabilizing circuit composed of U1, R1, and Z1; DC/DC converter circuit composed of U2 as the core; and a set of isolated power supply composed of L2 and U3. The system is designed to be concise and highly integrated, and all selected components can work at -40 ~ 85 ℃, which can ensure the reliable application of the power supply to field transmitters.Fig.1 Schematic Diagram of Power Supply III. Constant Current Voltage Stabilizing Circuit As a power supply to the two-wire transmitter, the maximum working current is 4mA. The transmitter with this power supply needs some low zero output indication, so the general system power supply standard is usually below 315mA, meanwhile, this type of power supply must have constant current characteristics to meet the operating requirements of the two-wire transmitter. And there are many ways to design constant-current sources. The design in Fig.2 adopts the three-terminal adjustable voltage stabilizer LM317L to design a constant-current source. LM317L is a three-terminal adjustable voltage stabilizer, and its application is as follows in Fig.2. Its basic application as a standard regulator is shown in Fig.2 (a), where a steady pressure difference is generated between the output and adjustment terminal, the typical value is 1125V, so its output voltage is VO=1125 (1+Ra/Rb). Because of the stable pressure difference of LM317, it is often used to design the constant-current source. Fig.2 (b) is a typical application circuit, which generates a current of I=1125 / R, consulting Fig.1; the R1 value in the design is 360Ω, so you can obtain a constant current of about 315mA.  Considering the working voltage range of the subsequent DC/DC chip is 4~11V and the actual out the power supply, a voltage stabilizer Z1 with 812V is used to parallel the voltage stabilizing function while providing a stable inlet voltage for U2. It requires that the U2 total current consumption is less than 314mA and Z1 must be the high-quality voltage stabilizer with the breakdown current less than 011mA (Philips products can be used, the lowest static stable current is only dozens of μA). Fig.2 Typical Application of LM317LThe D1 of the front end of the circuit is an anti-inversion diode( as shown in Fig.1), generally using 1N4148. The fuse is the PTC device self-recovery fuse, its parameter is 100mA/ 60V, which ensures that the external power supply will not be affected when the power supply fails. The field transmitter is the final application of the power supply. Its changing ambient temperature is in a wide range, so the temperature drift must be taken into account. The main temperature drift of the power supply is the constant current drift, which is caused by the temperature drift of the reference voltage difference of LM317L and the temperature drift of the constant current resistance R1. In reality, the temperature drift can be neglected when the temperature coefficient is below 5*10-6/℃.  The relationship between the reference pressure difference and temperature coefficient of LM317L is shown in Fig.3: The temperature effect is obvious in the temperature range of - 40-85%, thus compensation must be made in the high precision application. In intelligent transmitter systems, in order to correct sensors and compensate circuits, temperature sensors are commonly designed in the transmitter circuits, because the practical applications of power supply are aimed at intelligent transmitters. But the digital thermometric chip, like LM75 or TC77, does not design a special hardware compensation, while a software compensation algorithm provided when applying power supply to deal with temperature drift.  Fig.3 LM317L Benchmark Temperature CurveAs shown in Fig.3, the curve of the relationship between the reference pressure difference and temperature of LM317L is approximate to a simple cubic polynomial function. It only needs to design a compensation function for the reverse Y-axis, and the system is calibrated at 20 ℃ as the basic compensation. The specific compensation formula is ΔI=A (t-20)2+B (t-20) in which “t” is the ambient temperature. The coefficients A and B can be derived from the reference voltage temperature curve provided by the LM317L chip manual, the simplest method is to obtain two binary linear equation groups for solving A and B by taking two points of -20 ℃ and 60 ℃. In this way, it is easy to obtain an approximate function of the compensation curve with a good fitting degree, and the effect of compensated temperature drift can be neglected basically. The biggest difficulty of power supply design is that the input power is very small, thus the isolated feedback mode with high power consumption should be avoided in the design of the isolation terminal, and the open-loop auxiliary side should be used in the actual circuit. The specific process is using MAX639 to design the core circuit of DC/DC, which realizes the high power efficiency conversion. For example, when the input of 315mA is supplied, it can supply the circuit with a current much larger than that of 315mA, thus solving the need for a large current in an intelligent system. According to the requirements of the system, the core chip must have the advantages of low power consumption, high efficiency, wide input voltage range, and simple peripheral devices. The DC/DC chip in Fig.1 is MAXIM's MAX639, which is a step-down converter chip. Its main features are wide input voltage range (4~115V), high conversion efficiency (up to 90%) and low static current (10 μ A); fixed output or an adjustable output. IV. DC/CD in Circuit The circuit is designed for adjustable output and the output is set to 3V. Output current: Io=（Vi Ii η）/Vo, Vi is the input voltage; Ii is the input current, and η is the conversion efficiency and Vo is the output voltage. In the circuit, Vi=812V, Ii=315mA,η= 90%, Vo=3V, getting an approximation Io=816mA without considering the isolating side output, this output current is already a relatively large supply capacity in the low-power system. But the calculation of the above Io is only theoretical, if you want to make the circuit operate reliably under the condition of micro-input power such as 315mA/812V, and to obtain more than 90% conversion efficiency, it is necessary to design the circuit very carefully. The reliable operation of DC/DC is restricted by many conditions, the necessary condition is providing sufficient start-up pulse current. A 10μF tantalum electrolytic capacitor C2 in parallel to Z1 provides an operation guarantee, also it can effectively avoid the interference of DC/DC work on the constant current of LM317. The inductance L1 plays a decisive role in the conversion efficiency of DC/DC. The algorithm provided by the MAXIM manual is L1=50/I0, μH is the unit of L1 and A is the unit of I0. In the practical circuit, the value of L1 is 4mH, which can ensure the circuit work stably under the maximum output power, and it can keep the high conversion efficiency at the same time. what should be emphasized is that if L1 is small, the conversion efficiency of the circuit will be reduced, the starting current will increase and even can not operate. If L1 is larger, the output capacity will decrease and the DC/DC circuit will oscillate. To ensure the stability of the circuit, DC / DC chip has a high requirement for output capacitor C3, the most important is that its equivalent series resistance ESR must be smaller, and it must have enough capacity at the same time. So a 10μF tantalum electrolytic capacitor with excellent performance is used in the circuit design, which can guarantee a stable output. The DC/DC chip is the core of the circuit, and the actual circuit layout has a great influence on the performance of the circuit, especially on the output ripple. The unreasonable layout design of the circuit board will even bring extra parasitic oscillation in the output, so much more attention should be paid to the design. Thus the most important principle is that the ends of C2 and LI lead should be as close as possible to the MAX639 pin, and the grounding pins of C2, D2, MAX639, R3, and C3 should be as close as possible to each other, linking with thick wires. The setting input voltage of DC/DC is 812V, which is guaranteed by Z1. If the actual transmitter requires a lower power supply, Z1 can choose a lower stable voltage, which makes the whole power supply require a lower input voltage. The low threshold of the inlet voltage is 12V; if Z1 selects 612V, the threshold voltage can be reduced to 10V. V. Isolated Power Source Winding The main feature of the circuit is to provide an isolated power supply winding, which uses the method of "stealing" electricity on the DC/DC output energy storage inductor. In Fig.1, the L2 is the power supply coil for this isolated power supply. Because the isolating power supply is a secondary coil loaded on the energy storage coil of DC/DC, and its structure is an open loop, therefore its output stability is relatively poor. In order to obtain satisfactory results, it is necessary to consider the whole design from different angles.First of all: determine its output power. Because of the method of "stealing" electricity from the energy storage coil, its output power is limited and can only be smaller than the original side output power. The output of this set of isolated power supply is mainly supplied by sensor conversion circuit, front-end A/D converter, and isolated circuit in the application of specific transmitters. And the power consumption of analog measuring circuits of differential capacitance sensors, thermocouple sensors, and thermal resistance sensors reaches μA level. The front-end A/D is usually multi-integral or Σ-Δ, the power consumption is less than 1 mA, and the whole low power dissipation optoelectronic isolation can be below 1mA. Therefore, isolated windings provide 3mA that can meet the actual needs. It has been calculated that the maximum output of the circuit is 816mA without the secondary winding, so it is obvious that the 3mA current can be supplied in the case of the secondary winding. Secondly: Avoid working / hibernating rotation for devices with high power consumption. The isolation winding adopts an open-loop structure, and the change of load on the primary side directly affects the stability of the secondary side, so it is required that the power consumption stability of the original circuit system should be guaranteed as much as possible when the circuit is used in practice. What’s more, the circuit can provide the maximum 5mA current for the original edge and can fully meet the requirements of the commonly used low-power MCU control system without the use of sleep mode. In this way, the maximum system running speed can be obtained. Finally:  the low-voltage difference linear regulator and the DC/DC converter should be used in the design. The isolated power winding mainly supplies power to the front-end small-signal analog circuit, therefore, the quality of the power supply requires high. Noise reduction and voltage stabilization treatment of low voltage output converted by DC/DC through low dropout linear regulator(LDO), which can not only improve the efficiency of power supply but also meet the requirement of small ripple voltage. Specifically, LDO uses MAX1726 chip, its working current is the only 2μA, the output is 313V; The output amplitude before voltage stabilization depends on the output power of the original edge and the inductance of L2, the experiment confirmed that L2 is 3mH. When the primary current varies between 3~5mA and the secondary current is 2mA, the voltage fluctuates between 318V and 418V before the voltage stabilizes, which meets the input requirements of the LDO voltage stabilizer. VI. Conclusion The isolated power supply of two-wire transmitter is stable and reliable, and can meet various complex requirements of the use of two-wire transmitter. It has the characteristics of wide temperature range, wide input voltage range, high output efficiency, high integration, good isolation performance, small volume and low cost. And this power supply has been applied to the integrated intelligent temperature transmitter, after a long period of field test, finding that it has excellent performance and can fulfill the requirements of the isolated two-wire transmitter completely. FAQ 1. What does a transmitter do?In the Telecommunications world, a Transmitter is a device that produces radio waves radiating from an antenna. In the world of process control, a Transmitter is a device that converts the signal produced by a sensor into a standard instrumentation signal representing a process variable being measured and controlled. 2. What is called transmitter?In electronics and telecommunications a transmitter or radio transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. 3. What is transmitter and its types?Pressure transmitters are divided into three types: Absolute Transmitter: This transmitter take vacuum pressure as its base, and then measures process pressure. Gauge Transmitter: This type measures process pressure with the location's atmospheric pressure as a base. 4. What are the main features of transmitter?Some of the main features which make the transmitter complex are higher clock speed, higher transmit power, directional antennas and need for a linear amplifier. 5. What is transmitter frequency?A radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. Radio waves are electromagnetic waves with frequencies between about 30 Hz and 300 GHz. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. 6. What is the difference between transmitter and antenna?A transmitter is a different kind of antenna that does the opposite job to a receiver: it turns electrical signals into radio waves so they can travel sometimes thousands of kilometers around the Earth or even into space and back. Antennas and transmitters are the key to virtually all forms of modern telecommunication. 7. What is difference between transmitter and transducer? Transducers and transmitters are virtually the same thing, the main difference being the kind of electrical signal each sends. A transducer sends a signal in volts (V) or millivolt (mV) and a transmitter sends a signal in milliamps (mA). 8. What is transmitter PLC?Transmitters are also referred to as stationary instruments and convert measurement parameters into an electrical signal that is then sent to a BMS ( Building Management System), PLC ( Programmable Logic Controller), SCADA ( Supervisory Control and Data Acquisition). 9. What is the pressure transmitter?A Pressure Transmitter is an instrument connected to a Pressure Transducer. The output of a Pressure Transmitter is an analog electrical voltage or a current signal representing 0 to 100% of the pressure range sensed by the transducer. 10. Which oscillator is used in transmitter?Crystal oscillators are the most common type of linear oscillator, used to stabilize the frequency of most radio transmitters, and to generate the clock signal in computers and quartz clocks. You May Also LikeThe 3W PowerSpot transmitter for Power Over-the-air from PowercastBuild a Remote RC Firecracker and Firework lgniter Using RF Transmitter4 Channel 2 Core Twisted Pair Remote Controller Using PT2262

IntroductionMany embedded designs use single board computer based on micro-processor and micro-controller(SBC) and modular system (SoM). However, people with more embedded applications can't bear the delay caused by the response time associated with software. Only the custom hardware can achieve the higher performance that these applications required, and the quickest way to develop custom hardware is to use FPGA. This article will introduce the advantages of using SoM to develop embedded systems that require higher processing power from FPGA, and will also cover the various FPGA SoM, and also discuss how they work when embedded in design and development.What is an FPGA? Intro for BeginnersCatalogs CatalogsFPGA: The Role of Modular SystemNew SoM based on SoC with processor and FPGAFunctions of SoM and SBCConclusion FPGA: The Role of Modular SystemThe modular system (SoM) can help designers to develop special shape size embedded systems with custom interfaces without having to develop kernel processing systems from scratch. Designers can insert SoM which has pre-designed and tested into pre-designed or customized cards to create embedded designs with the same functions as fully customized designs, but take much less time to develop hardware.Using SoM has several advantages over developing hardware from scratch as follows:1) Saving cost( in the process of developing and debugging the circuit board based on SoC, the non-recurrent engineering cost will be very high.)2) Multiple choices(benefiting the insertion ability of SoM)3) Developing hardware and software at the same time4) Reducing design risks5) Small packagesThe market, once dominated by microprocessors and micro-controllers, is now replaced by SoM, with through holes and socket components losing their leading role. Pin compatibility allows designers to select from a range of compatible processors that have the correct clock speed and appropriate on-chip memory capacity. However, with the increase of the number of pins and the adoption of surface mount packaging technology, this design method has become obsolete. And SoM has emerged as the times require, its shape size and substrate surface have the same function as the previous series of pin compatible micro-controllers.If SoM is used as the computing platform of the project, the design engineer can concentrate his energy and resources to develop the final application without being lost in the details of designing computing platform. For example, at the clock speed of hundreds of megahertz (MHz), the layout of the SDRAM circuit board connected to the application processor becomes increasingly difficult due to differential wire delay, noise, crosstalk and many other challenges. However, SoM vendors have done a lot of design work before the start of the project, which can solve these problems and cut the time of product launch.To select the appropriate SoM series for embedded development projects, we must carefully analyze various factors, including the expected requirements of embedded resources, as well as the design extendibility, future adaptability and ease of use. This helps to select the appropriate shape and substrate size of SoM, providing alternative options to meet known challenges and unexpected future challenges. If the selected SoM family includes multiple product members and has compatible appearance dimensions and connector base surfaces, the selection of the designers can be expanded to make the product better able to withstand the test of the future. New SoM based on SoC with processor and FPGASoM usually uses SoC which includes multiple application processors, but a new embedded processor, SoC, integrating FPGA, applies to the SoM design either, like the Zynq®-7000 SoC, Xilinx’s fully programmable processor. Xilinx Zynq-7000 SoC integrates the software programmability of Arm Cortex-A9 application processors with the hardware programmability of FPGA. Arm microprocessor, built in Zynq SoC,  combines enhanced peripherals with SDRAM memory controllers (called Zynq SoC's "processing systems" or "PS"), and performs all the software-based tasks typically handled by embedded microprocessors or microcontrollers, while integrated FPGA (known as Zynq SoC's PL: Programmable Logic) provides hardware I / O response time and hardware acceleration for embedded tasks that require faster execution speed.Xilinx Zynq SoC offers a variety of processor configurations and speeds, with even more options for FPGA structures on a chip. Choosing the SoM family based on hybrid processor FPGA SoC can expand the selection range and improve the future adaptability of the product, like Xilinx Zynq-7000 series. One example of such a SoM series is the use of the TE0782 family from Trenz Electronic (Fig.1) and the SoM supporting test panel TEBT0782-01 which adopts the Xilinx Zynq-7000. Three Members of the SoC FamilyTE0782-02-035-2I based on Xilinx Zynq Z-7035 SoCTE0782-02-045-2I based on Xilinx Zynq Z-7045 SoCTE0782-02-100-2I based on Xilinx Zynq Z-7100 SoCAll three SoMs have the same connector substrate, including three Samtec LSHM nonpolar connectors and hundreds of I / O pins, in addition, there are power and grounding pins between the SoM and the board.Fig.1 Trenz Electronic TE0782 SoMFig.1: TE0782 SoM from Trenz Electronic uses one of three Xilinx Zynq Z-7000 SoC models, as well as providing 1GB SDRAM and other non-volatile memory.The best way to see the flexibility of SoM design is to look at the TE0703 carrier board of the TE0782 SoM family, and then go back to SoM through the I / O pins to see SoM's resources.Fig.2: Trenz TE0703 Board Divides Many I / O Pins from the Relevant 4 x 5 cm SoM Boards to the Rest of the Embedded System.Many of the important I / O functions separated from the SoM board are shown in the block diagram of TE0703 as follows:1 Gbit/s EthernetUSB and Micro-USBHundreds of I/O pins(it can be configured as a singular I / O pin, or as a low-voltage differential signal pair.)Fig.3 Physical Map of Trenz TE0703-05( Trenz TE0703 family) Functions of SoM and SBCProcessing speed, response time and I / O capability are significant characteristics of SoM. However, embedded systems often integrate SBC, such as Arduino Uno and Raspberry Pi, because these products also have wide-ranging technique support. So Trenz Electronic also offers related versions of Arduino and Raspberry Pi: TE0723-03M ArduZynq and TE0726-03M ZynqBerry based on Xilinx Zynq-7000 SoC. These SBC bridges many existing plug-in cards, such as the expansion boards of  Arduino and various Raspberry.The FPGA capacity of Zynq Z-7010 SoC integrated into TE0723-03M ArduZynq and TE0726-03M ZynqBerry SBC is significantly different from that of FPGA integrated into three Trenz Electronic SoMs (using Zynq Z-7035 Zynq Z-7045 and Zynq Z-7100 SoC ). Although all Zynq-7000 SoC apply dual-core Arm Cortex-A9 processor, their FPGA on components are different. Volume of the Xilinx Zynq SoC Programmable Logic Unit Block RAM (MB) DSP slices is Z-701028K2.180Z-7035275K17.6900Z-7045350K19.2900Z-7100444K26.52020, Xilinx Zynq-7000 SoC (Z-7035, Z-7045 and Z-7100) used in Trenz Electronics SoM provides more FPGA resources than that of Zynq Z-7010 used in Trenz Electronic ArduZynq and ZynqBerry SBC.Xilinx Zynq-7000 SoC (Z-7035, Z-7045 and Z-7100) used in Trenz Electronics SoM provides more FPGA resources than that of Zynq Z-7010 used in Trenz Electronic ArduZynq and ZynqBerry SBC. In addition, TE0723-03M ArduZynq and TE0726-03M ZynqBerry SBC provide only 512-MB on-board SDRAM, while TE0782 SoM provides 1GB.Trenz Electronic provides various boards for its SoM, including TE0703-05, TE0706-02, TE0701-06, and TEB0745-02, which provide a lot of standardized I / O functionality. A certain card may be suitable for a particular embedded application, but the embedded system design can also be split into a customized design board that can accept SoM series products to meet different processing requirements. This flexibility highlights the advantages of using the SoM family as the basis for embedded design. And consistent standardized connector substrate allows SoM to be easily interchangeable to accommodate changes in system specifications. ConclusionSoM can significantly cut the time requirement of prototype embedded systems and reduce project risk. As long as the SoM profile and connector substrate are supported,  more FPGA resources of SoM can be inserted to meet the growing demand. In addition, a variety of compatible SoM based on Xilinx Zynq-7000 SoC combine the processing power of dual-core Arm Cortex-A9 processor with FPGA resources, which is helpful to accelerate the development of embedded design. The embedded design method based on SoM can not only shorten the time required to develop the hardware part, but also allow the software development to start earlier in the project, thus reducing the design cost. FAQ1. What is a FPGA used for?Image result for FPGA and ProcessorFPGAs are mainly used to design application-specific integrated circuits (ASICs). First, you design the architecture of such a circuit. Then, you use an FPGA to build and check its prototype. Errors can be corrected. 2. Is an FPGA a processor?With an FPGA, there is no chip. The user programs the hardware circuit or circuits. The programming can be a single, simple logic gate (an AND or OR function), or it can involve one or more complex functions, including functions that, together, act as a comprehensive multi-core processor. 3. What is difference between FPGA and processor?CPUs offer the most versatility and so are the best suited to perform general purpose computing. FPGAs can be used to perform more specific and specialized tasks but are not ideal for general computing purposes. 4. How many times can you reprogram an FPGA?Altera guarantees you can reprogram windowed EPROM-based devices at least 25 times. Altera does not specify the number of times you can reprogram or reconfigure FPGA devices because these devices are SRAM-based. An SRAM-based device can be reconfigured as often as a design requires; there is no specific limit. 5. What is SoM FPGA?The CompactRIO System on Module (SOM) is a small, flexible, embedded computer for industrial applications that require high performance and reliability. It combines an ARM processor, the NI Linux Real-Time OS, a programmable Xilinx FPGA, and a high-density connector to interface with application-specific I/O. You May Also LikeDiscussion on the influencing factors of clock in FPGA designTo Solve the Problems of Cloud Skyrocket--Edge Processing

This paper introduces a switching power supply with the half-bridge circuit. Its input voltage is AC 220V ±20V, the output voltage is DC 4V ~16V, the maximum current is 40A, and the working frequency is 50kHz. And its design idea, working principle, and characteristics of the power supply are introduced emphatically. 12V 10A switching power supply (with schematic and explanation)   Catalog   I. Introduction II. Main Technical Indicators III. Main Functions Description 3.1 AC EMI Filter and Rectifier Filter Circuit 3.2 Half-bridge Power Converter 3.3 Design of Power Transformer 3.4 Design of Auxiliary Power Supply 3.5 Drive Circuit 3.6 Fan Wind Speed Control Circuit 3.7 PWM Control Circuit 3.8 Current Fold back Circuit FAQ       I. Introduction Power supplies with the voltage of 5~15V and current at 5~40A are most commonly used in scientific research, production, experiments and other applications. The maximum current of the general experimental power supply is only 5A or 10A, For this purpose, a switching power supply with continuously adjustable voltage at 4V~16V and maximum output current of 40A has been developed. It adopts half-bridge circuit, with power MOS transistor as switching device and the switching frequency is 50kHz. Light weight, small volume and low cost are advantages of it.   II. Main Technical Indicators   1) Output Voltage: AC 220V±20％  2) Input Voltage: DC 4～16V(adjustable) 3) Output Current: 0~40A 4) Output Voltage Adjustment Rate: ≤1％ 5) Ripple Voltage Up: p≤50mV 6) Current / Voltage Display Function and Fault Alarm Indication   Basic Working Principles and Schematic Diagrams The schematic block diagram of the power supply is shown in Fig.1. After 220V AC voltage is filtered by EMI and rectifier, about 300V DC voltage is added to the half-bridge converter to drive the power MOS tube with the dual pulse signal generated by the pulse width modulation(PWM) circuit. The quasi-square-wave voltage is gained by coupling and isolating the power transformer, and a stable DC output voltage can be obtained by rectifying filter feedback control. Fig. 1 Working Block Diagram of Integral Power Supply   III. Main Functions Description   3.1 AC EMI Filter and Rectifier Filter Circuit Fig.2 AC EMI Filter and Input Rectifier Filter Circuit The power line of the electronic equipment is an important way of electromagnetic interference (EMI) to get into or out of the electronic equipment, but installing the power line filter at the entrance of the power line of the equipment can effectively cut off the transmission path of EMI. And it composed of IEC plug power filter and PCB power filter.   The main purpose of the IEC plug power filter is to prevent the interference from the power grid from entering the power supply box, and for PCB power filter the purpose is to suppress the high frequency noise generated when the power switch is switched. Bridge rectifier circuit is used when AC input voltage is 220V, if JTI jumper is short-connected, then 110V is suitable.   Because the input voltage is high and the capacitor capacity is large, the surge impulse current will be produced at the moment when the power network is switched on, and the general surge current value is tens of times that of the steady current.   This may result in the damage of rectifier bridge and input fuse, or the saturation damage to power devices of high frequency transformer cores, and the reduction of the service life of high voltage electrolytic capacitors, etc. So the input soft start circuit composed of resistance R1 and relay K1 is added in front of rectifier bridge to avoid those damages.   3.2 Half-bridge Power Converter The power supply uses half-bridge converter circuit, as shown in Fig.3, its operating frequency is 50kHz, the main parts on the primary side are power transistors: Q4 and Q5, and capacitors: C34 and C35. Q4 and Q5 alternately conduct and cutoff, A positive and negative square wave pulse voltage of U1/2 is generated through the primary winding N1 of a high frequency transformer. The energy is transferred from transformer to the output, and Q4 and Q5 use IRFP460 power MOS transistor. Fig.3 Switching Power Supply Schematic   3.3  Design of Power Transformer   1) Setting of the Working Frequency The working frequency has a great influence on the volume, weight and circuit characteristics of the power supply. The output filter inductance and capacitance volume decrease with high working frequency, but the switching loss increases, the heat quantity increases and the radiator volume increases. Therefore, according to the factors such as components and cost performance, optimizing the operating frequency of power supply, the formula is fs=50kHz, T=1/fs=1/50kHz=20μs.   2)Core Selection ①Selecting the EE type ferrite core made of R2KB ferrite material, has many advantages, such as versatility, large lead space, convenient wiring operation, economics, and so on. ②Determination of Working Magnetic Induction Intensity: Bm The saturation magnetic induction intensity of R2KB soft magnetic ferrite material is Bs=0.47T, considering that Bs will decrease at high temperature, and in order to prevent the saturation of high-frequency transformer at the moment of closing,  selecting Bm=1 / 3Bs= 0.15T ③Calculation and Determination of Core Type The geometric cross-sectional area S and the window area Q of the magnetic core have a certain functional relationship with the output power Po. For half-bridge converters, when the pulse waveform is an approximately square wave, having SQ= (1) η—Efficiency j—Current density, generally 300~500A/cm2 kc—Fill factor of magnetic core, ferrite core kc=1 Ku—Filling coefficient of copper, related to the wire diameter, winding process, winding number, and so on, is generally about 0.1~0.5. The units of each parameter: Po—W，S—cm2, Q—cm2, Bm—T, fs—Hz, j—A/cm2. The values each parameter:  Po=640W，Ku=0.3,j=300A/cm2,η=0.8,Bm=0.15T, plugging these into formula(1) to get SQ=4.558cm4. From the manufacturer manual of EE55 magnetic core: S=3.54cm2, Q=3.1042cm2, calculating SQ=10.9cm4, the SQ value of EE55 magnetic core is larger than the calculated value. EE55 magnetic core is the option.   3) Calculating Turns of Primary and Secondary Side Windings Calculate the primary number turns of windings according to the lowest input voltage and the full load(the duty ratio is maximum). It is known that the DC input voltage of Umin=176V after rectifying and filtering is Udmin=1.2 × 176 = 211.2V. For the half-bridge circuit, the voltage applied on the primary winding of the power transformer is equal to half of the input voltage, that is Upmin=Udmin/2=105.6V, assuming Dmax=0.9(the maximum duty ratio), getting tonmax= T × Dmax= 20 × 0.9 μs.   Design of an Output Voltage 4~16V Switching Power Supply   Fig.4 Schematic Diagram of Auxiliary Power Supply Upmin×tonmax×104=105.6×9.0×10－6×104, plugging into formula N1=8.9 turns,  the maximum output voltage is Uomax=16V when calculating secondary turns; the secondary circuit uses full wave rectifier, Us as the inductive voltage on the secondary winding and Uo as the output voltage and Uf as the rectifier diode voltage drop, taking 1 V as the voltage drop, Uz is filter inductor equal circuit voltage drop taking 0.3V, getting Us=19.22V×N2=N1×8.9=1.8 turns; For the convenience of winding the transformer, if the secondary winding is 2 turns, then the primary winding will be corrected to N1=N2=10 turns.   4) Selected Wire Diameter When selecting the wire diameter of the winding, the skin effect of the wire should be considered. It is generally required that the wire diameter be less than two times the penetration depth, and the penetration depth Δ is determined by formula (2), Δ= (2), and the unit of penetration depth Δ is m. In formula ω is the angular frequency: ω=2πfs; μ is magnetic conductivity, for the relative permeability of copper wire: μr=1 , 则μ=μ0×μr=4π×10－7H/m; γ is the conductivity of copper, γ = 58 × 10 —6Ωm. The operating frequency of the transformer is 50kHz, and the penetration depth of the copper conductor is Δ=0.2956mm at this frequency, thus the diameter of the winding wire must be copper wire whose diameter is less than 0.59mm. In addition, the current density of copper wire is generally 3 ~ 6 A / mm2, the 0.56mm enamelled wire with 8 strands in parallel for the primary is 10 turns, and the thick 0.15mm flat copper strip with 2 turns in the secondary.   3.4 Design of Auxiliary Power Supply The auxiliary power supply using RCC converter (Ringing Choke Converter), is shown in Fig.4. The input voltage is AC 220 V, as rectifier filter voltage, and the output DC voltage is 12.5 V, the output DC current is 0.5 A. In the circuit, Q8 and transformer primary winding N1 and feedback winding N3 constitute self-excited oscillation. R72 is starting resistance. Q9, R77 constitutes primary overcurrent protection of auxiliary power supply. D20, C81, ZD1, Q11, R75, N76 constitutes voltage detection and voltage stabilizing circuit. The DC component of the base current of Q 8 keeps the output voltage constant, and the transformer is made of EE19 material and LP3 material. The primary is 180 turns, the feedback winding is 5.5 turns, the secondary is 11 turns, the primary inductance is 2.6 MHz, the core gap is 0.4mm.   3.5 Drive Circuit The drive circuit is shown in Fig.5. TL494 outputs the pulse signal of 50kHz and drives the power MOS transistor through the coupling of a high-frequency pulse transformer. The secondary pulse voltage is a timing MOS switch, during which Q7 ends, and the drain circuit formed by it does not work. Q7 conducts when the second pulse voltage is 0, rapidly releasing the gate charge of MOS, and accelerating MOS cutoff. R70 is the spike to suppress the driving pulse, R68, D15, R67 used to speed up driving and suppress the oscillation caused by driving pulse, D17, and the connected pulse transformer windings form a demagnetization circuit.  Fig.5 Driving Circuit Schematic Diagram 3.6 Fan Wind Speed Control Circuit Fan wind speed control circuit is shown in Fig.6. Based on the decreasing trend of diode forward tube pressure drop with increasing temperature, D9 and D10 are used as radiator temperature samplers close to the radiator. When the temperature of the radiator rises with the increase of output power, the level of the positive phase input of the operational amplifier N2A decreases, the output low level causes the transistor Q3 to start conducting, and the voltage on the fan rises.   The rotational speed rises and finally reaches the maximum speed. When the load is lighter and the radiator temperature is lower than 50 ℃, the output of N2A is high level, Q3 is not conductive, and auxiliary electricity 12.5V stepped down by resistance R57 supplying to fan, thus the fan is running at low speed and low noise. The circuit can improve the working life of the fan, increase the reliability of the circuit and reduce the noise caused by the fan in the case of a small load.   Fig.6 Fan Wind Speed Control Circuit 3.7 PWM Control Circuit The general pulse width modulator (TL494,) used in the control circuit has the advantages of generality and low cost, as shown in Fig.7. The output voltage is sampled by R40, RV2, RV1, R41 and then sent to the TL494 pin 1 after the R5 impedance matching. RV1 installed in power front panel to realize the output voltage adjustment. R103 and C14 sample the output inductor L1 front signal which delivering through R5 to TL494 pin 1 to improve power supply stability and eliminate the influence of L1 on loop stability.   3.8 Current Foldback Circuit In order to enhance the reliability of the power supply, this power supply adopts two-stage over-current protection: primary and secondary. Current transformer CT1 is initially used to detect the primary transformer current. The detected current signal is converted from R60 to voltage signal, then filtered by D2~D4 and C9, and then the voltage is divided by potentiometer RV3, and inverted by N3, finally added to the Q 1 tube base. When the primary current is abnormal, the inverter reverses the Q1 switch and adds a high level of VREF=5V to the TL494 pin 4 (the TL494 dead-zone control pin, which is turned off at a high level), TL494 is off. Overcurrent protection on the main output DC line uses R45-R56 resistance as the sampling resistance. When the output current increases, the level of pin15 becomes lower. When the output current is greater than 105% of 40A, the internal operational amplifier of TL494 acts. The pin3 level rises, limiting the increase of the output pulse width, and the power supply is in the limiting state. FAQ   1. How does a switching power supply work? The “switch” in a switching power supply is actually a semiconductor – a MOSFET that is either off or on – driven into its saturation range to transfer power across nearly zero resistance. It does this many thousands of times per second, creating the high-frequency AC intermediary.   2. What is difference between linear 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.   3. What is a switching power supply 12v? Switching regulated 12VDC power supplies, sometimes referred to as SMPS power supplies, switchers, or switched mode power supplies, regulate the 12VDC output voltage using a complex high frequency switching technique that employs pulse width modulation and feedback. Acopian switching regulated power supplies also employ extensive EMI filtering and shielding to attenuate both common and differential mode noise conducted to the line and load. Galvanic isolation is standard in our 12VDC switchers, affording our users input to output and output to ground isolation for maximum versatility. Acopian switching regulated power supplies are highly efficient, small and lightweight, and are available in both AC-DC single and wide-adjust output and DC-DC configurations.   4. 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.   5. When should you use a switching power supply? Switching power supplies are primarily used in digital systems such as telecommunication devices, computing equipment, audio equipment, mobile phone chargers, medical test devices, arc welding equipment and automotive chargers.   6. Is a switching power supply regulated? A switch mode power supply regulates an output voltage with pulse width modulation (PWM). This process creates high-frequency noise but it provides a high-efficiency rating in a small form factor. ... The low DC voltage is finally converted into a steady DC output with another set of diodes, capacitors, and inductors.   7. Is a switching power supply DC? A switching power supply takes an AC input, but rectifies and filters into DC first, is converted back into AC at some high switching frequency, steps down the voltage with a transformer, then is rectified and filtered into a DC output.   8. How do I know if my power supply is regulated? You can generally stick one probe into the middle of the connector, and hold the other against the outside. With a few exceptions, the middle is positive, so use the red lead there, and use the black lead on the outside shell. Regulated supplies, without any load, should measure very close to the target voltage of 12v.   9. 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.   10. 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.   You May Also Like Learn Some Basic Knowledge about Capacitor Voltage Transformer The Latest Development of Electric Vehicle Power Management Technology Design a Momentary Pushbutton in the Circuit of Laching Power Switch