In this article, we will provide you the basic introduction to FPGA and ASIC, illustrate their differences in the design, and many other complement content. CatalogI. What is FPGA?II. What is ASIC?III. What is the Difference Between FPGA and ASIC?      3.1 Difference in RTL Design      3.2 Difference in Development ProcessIV. Difference SummaryFAQI. What is FPGA?The circuit design with hardware description language (Verilog or VHDL), which can be easily synthesized and distributed, can be quickly made to FPGA for testing. It is the mainstream of modern IC design verification technology. These editable elements can be used to implement basic logic gates (such as AND, OR, XOR, NOT) or more complex combinatorial functions such as decoders or mathematical equations. In most FPGA, these editable components also contain memory elements such as triggers (Flip-flop) or other more complete memory blocks.System designers can connect blocks of logic inside FPGA via editable connections as needed as if a circuit test board had been placed in a chip. The logic blocks and connections of a finished FPGA can be changed according to the designer, so FPGA can meet the required logic functions.The speed of FPGA is generally slower than that of ASIC, and the area of realizing the same function is larger than that of ASIC. But they also have many advantages, such as quick production, modification to correct errors in the program, and cheaper costs. Vendors may also offer cheap but poorly edited FPGA. Because these chips have poor editable capabilities, the development of these designs is done on an ordinary FPGA, and then the design is transferred to a chip similar to ASIC. Another way is to use CPLD (Complex Programmable Logic Device). Learn the basics of what is an FPGA. This video discusses the history of FPGAs and how they have advanced over time. It discusses some applications that are possible. Finally it will introduce the two languages used to program FPGAs: VHDL and Verilog.  FPGA StateFPGA (Field Programmable Gate Array) is the product of further development on the basis of PAL, GAL, CPLD, and other programmable devices. As a semi-custom circuit in the field of ASIC, it not only solves the deficiency of custom circuits but also overcomes the shortcoming of the limit of the gate of the original programmable device, that is, FPGA allows unlimited programming. FPGA Parts ExplainationFPGA adopts the concept of LCA (Logic Cell Array), which includes three parts: configurable logic module (CLB), Input-Output Block(IOB), and Interconnect. FPGA is a programmable device with different structures compared with traditional logic circuits and gate arrays (such as PAL, GAL, and CPLD devices). FPGA uses a small lookup table (16×1RAM) to implement combinatorial logic. Each lookup table is connected to the input of a D-trigger, which drives other logic circuits or drives the I / O. Therefore, the basic logic unit module can realize both combinational logic function and sequential logic function. These logic units connect with mental wires or I/O contracts. In addition, the logic of FPGA is to load programming data into internal static storage units. The value stored in the memory cell determines the logical function of the logical unit and the connection between modules or between modules and I / O contracts and ultimately determines what FPGA can achieve.II. What is ASIC?An application-specific integrated circuit(ASIC) is a microchip designed for a special application, such as a special kind of transmission protocol or a hand-held computer. People might contrast it with general integrated circuits, such as the microprocessor and the random access memory chips in PCs. ASIC is used in a wide range of applications, including auto emission control, environmental monitoring, and personal digital assistants (PDAs).Mining was for a long time a GPU only game, but with ASIC miners seemingly everywhere these days, are they actually profitable? ASIC StateAt present, ASIC is considered to be a kind of integrated circuit designed for special purposes in the field of integrated circuits. An integrated circuit is designed and manufactured at the requirement of a specific user or a particular electronic system. That is, the ASIC is characterized by a request for a specific user. The ASIC is smaller in volume and lower in power consumption than that of a general integrated circuit in mass production, also has the advantages of improved reliability, improved performance, enhanced confidentiality, lower cost, and so on. Full Customization and Semi-customizationASIC is divided into full customization and semi-customization, so an ASIC can be pre-manufactured for a special application or it can be customized (typically using components from a "building block" library of components) for a particular requirement of customers.Full customization design requires designers to complete the design of all circuits, so it requires a lot of manpower and material resources, although it has good flexibility the development efficiency is low. If the design is ideal, full customization can run faster than semi-custom ASIC chips. When using the standard cell, the semi-custom can select SSI (gate), MSI (such as adder, comparator, etc.), data path (such as ALU, memory, bus, etc.),. memory and even system-level modules (e.g. multipliers, microcontrollers, etc.) ) and the IP core from the standard logic unit library. When these logic units have been laid out and designed reliably, the designer can easily complete the system design. Modern ASIC often contains a 32-bit processor, storage units like ROM, RAM, EEPROM, Flash, and other modules. Such ASIC is often called SoC(system in the chip).ASIC DevelopmentProgrammable ASIC is another characteristic branch of ASIC development. It mainly uses programmable integrated circuits such as PROM, GAL, PLD, CPLD, FPGA, or logic array to get ASIC. Its main feature is to provide software design and programming directly, completes the function of ASIC circuit, and it does not need to be processed by IC process line.There are many kinds of ASIC designs for programmable devices, which can meet different requirements. PLD and FPGA are commonly used programmable devices. It is suitable for the design of digital circuits with a short development cycle, certain complexity, and circuit scale, especially for electronic system design engineers using EDA tools for ASIC design.III. What is the Difference Between FPGA and ASIC? 3.1 Difference in RTL DesignThere are many differences between FPGA and ASIC. The logic of ASIC is usually much larger than that of FPGA. There is an order of magnitude difference in gate numbers, and the running clock is much higher than FPGA. Moreover, FPGA is relatively flexible than ASIC because it can be programmed, but only in terms of RTL design: (1) ASIC tends to be more conservative, any changes to logic needed careful consideration, and make alternative choices in case of a correction. Any modification to RTL is almost incremental, and even if the previous logic is wrong, it will not be deleted, but one more branch is made.(2) ASIC has higher requirements for coding style. Coding style requirements for all modules are consistent, thus favoring the fault check.(3) ASIC design pays more attention to the clock and reset. In particular, clocks are critical to the design of ASIC, and reset is critical to BIST testing. ASIC uses libraries to design in this respect. ASIC usually does not use a counter to divide frequencies, which can lead to unclean clocks. Unless it's a very low-frequency clock, ASIC is also much more cautious about signal processing across clock domains. The closing and opening of the clock also need to be strictly checked.(4) ASIC has to consider the problems of SCAN testing and BIST, so it is necessary to do BIST insertion for SRAM when designing and to reserve interfaces for SCAN. Although most of the interfaces are done by tools, RTL authors often have to do some top-level complex work manually, logic such as the source of the SCAN clock.(5) FPGA often uses existing IP, it needs to consider the balance of resources because there is a problem of resource waste in FPGA. ASIC rarely needed to consider this problem, the main consideration of it is its performance and power consumption, except SRAM and CLK which is related to reset in logic choice, the other are handwritten. So the logic is basically no waste, and more compact.(6) ASIC timing is more predictable and adjustable, so it can write a lot of logic. 3.2 Difference in Development ProcessThe differences between FPGA and ASIC development processes: ASIC and FPGA Design Flow ASIC and FPGA Implementation StepsThe first step is to implement functionality in a way that is generally described in HDL, such as Verilog, VHDL. Of course, small-scale circuits can also use circuit diagram input mode.The second step is to ensure the correctness of circuit functions, also known as verification. It can be realized by software simulation, hardware simulation, and so on. Software simulation is generally intuitive and easy to debug because the state of every moment can be seen, this is like debugging software programs. Hardware simulation generally refers to FPGA verification, that is, the circuit is implemented with FPGA, and then run it. The advantage of this is that it is very fast. For example, a video decoding core is used to solve a frame of the image, and software simulation can even use the best server, it still takes a lot of seconds to run, but in FPGA, it basically needs milliseconds. For a large mode verification of the circuit, is essential.The first two steps for digital IP,  the ASIC and FPGA are basically the same, unless some implementation techniques are different.The third step is, once the correctness of the circuit you describe is ensured, to implement it by turning the code you write into a real circuit, such as a register or a NAND gate, which is called synthesis. Because the circuit is becoming more and more complex, the most basic circuit is made into cells, such as register, and non-gate, so it will not be refined to the problem of how to use triode. The difference of this step is the smallest unit of the FPGA and the ASIC. FPGA is a well-made circuit, generally considering universality and efficiency, so the basic circuit unit is relatively large, such as LUT, consist of a register and NAND gate, although it uses one gate, it will take up such a unit. For ASIC, the two-input NAND gate is a simple gate circuit, even in order to distinguish the driveability and the timing characteristic difference, there are several grades, some area is small, some driveability is strong. In general, this step is to make sure your description turned into a library-based circuit description.The fourth step is, when you get a description of the circuit based on the library, you have to consider how these units are placed, which is called layout and wiring. The wiring resources of FPGA are limited, so you need to constantly adjust it to ensure the timing requirements. Map your circuit to the middle of its fixed resource map. ASIC's words are generally based on peripheral circuit requirements, timing requirements, your circuit to a certain location on the chip. After the arrangement, we have to consider whether the connection can pass, whether the delay at all levels can meet the circuit establishing and maintaining time requirements, and so on.The fifth step is output. FPGA is to output a configuration file to make the FPGA chip configure its circuit so that it can achieve the desired function. This file can be downloaded by PC after FPGA power-up, or stored in Flash, when the circuit is powered on, the automatic configuration will make. ASIC is to output a layout file to tell the manufacturer how to corrode silicon chip, how to connect metal, and so on.The sixth step is cost. ASIC has a great advantage in terms of recurring costs with less material is wasted due to the fixed number of transistors in the design. As for FPGAs, a certain number of transistor elements are always wasted although these packages are standard. This means that the cost of an FPGA is often much higher than that of an ASIC. Although the recurring cost of an ASIC is quite low, its non-recurring cost is relatively high. Although it is non-recurring, its value per IC decreases with increased volume.  A Field Programmable Gate Array can be seen as the prototyping stage of Application Specific Integrated Circuits: ASIC is very expensive to manufacture, and once it's made there is no going back (as the most expensive fixed cost is the masks [sort of manufacturing "stencil"] and their development). FPGA can reprogrammable many times, however because of the fact that a generic array of gates is connected to accomplish your goal, it is not optimized like ASIC. Also, FPGAs are natively dynamic devices in that if you power it off, you lose not only the current state but also your configuration. Boards now exist though that add a FLASH chip and/or a microcontroller to load the configuration at startup so this tends to be a less important argument. Both ASIC and FPGA can be configured with Hardware Description Languages, and sometimes FPGA is used for the end product. But generally, ASIC kicks in when the design is fixed.If you analyze the cost of production in relation to the volume, you would find that as you go lower in production numbers, using FPGA actually becomes cheaper than using ASIC.There are, of course, various auxiliary steps in the process. In general, it's all about making sure that the circuits you design are correct and implemented correctly.IV. Difference Summary FPGAASICReconfigurable circuitOne-time circuitDesign mainly with hardware description languages (HDL)Similar to the FPGAFPGA is relatively flexibleASIC tends to be more conservativeFPGA is not strict with the coding because of its programming featureASIC has higher requirements for coding styleFPGA uses small LUT to combine logic configurationASIC design pays more attention to clock and resetFPGA designers generally do not need to care for back-end designThe problems of SCAN testing and BISTFPGA uses existing IPperformance and power consumptionAnalog designs are not possible with FPGAASIC can have complete analog circuitThe speed is generally slowerRun fast than FPGAAllow unlimited programmingAn integrated circuit for a special purposeMore power consumptionMuch more power efficient than FPGA Visual Comparsion(√ means better to select)FPGAASICNRE√Performance√Design Flow√Barrier to entry√Time to market√Analog Blocks√Unit size√Power consumption√Cost per unit√FAQ 1. How do FPGAs work?In general terms, FPGAs are programmable silicon chips with a collection of programmable logic blocks surrounded by Input/Output blocks that are put together through programmable interconnect resources to become any kind of digital circuit or system. ... Unlike processors, FPGAs are truly parallel in nature. 2. What is FPGA and why it is used?FPGAs are particularly useful for prototyping application-specific integrated circuits (ASICs) or processors. An FPGA can be reprogrammed until the ASIC or processor design is final and bug-free and the actual manufacturing of the final ASIC begins. Intel itself uses FPGAs to prototype new chips.3. What is the function of FPGA?The field-programmable gate array (FPGA) is an integrated circuit that consists of internal hardware blocks with user-programmable interconnects to customize operation for a specific application.4. Is FPGA faster than GPU?Compared with GPUs, FPGAs can deliver superior performance in deep learning applications where low latency is critical. FPGAs can be fine-tuned to balance power efficiency with performance requirements.5. Is Raspberry Pi a FPGA?The main difference between the Snickerdoodle and other single-board systems like the popular Arduino and Raspberry Pi products is the inclusion of a Field Programmable Gate Array (FPGA). 6. Does FPGA have memory?The FPGA fabric includes embedded memory elements that can be used as random-access memory (RAM), read-only memory (ROM), or shift registers. These elements are block RAMs (BRAMs), LUTs, and shift registers. ... The data of the ROM is written as part of the FPGA configuration and cannot be modified in any way.7. Is FPGA a microprocessor?Microprocessor vs FPGA: A microprocessor is a simplified CPU or Central Processing Unit. ... An FPGA doesn't have any hardwired logic blocks because that would defeat the field programmable aspect of it. An FPGA is laid out like a net with each junction containing a switch that the user can make or break.8. What is FPGA and ASIC?ASIC stands for Application Specific Integrated Circuit. ... The difference in case of ASIC is that the resultant circuit is permanently drawn into silicon whereas in FPGAs the circuit is made by connecting a number of configurable blocks.9. Is FPGA better than ASIC?In general, we can say that for lower volumes' designs, FPGA flexibility allows to save costs and obtain better results; while ASICs chips are more efficient and cost effective on high volume applications.10. Which one is faster ASIC or FPGA?A single unit of an FPGA chip will be relatively larger than an ASIC chip unit. Because FPGA has its internal structure and a certain size that cannot be changed – while ASIC consists of exactly the amount of gates required for the desired application. FPGA boasts a faster time to market than ASIC.11. What are the main differences between ASIC and FPGAs?Performance and Efficiency. ASICs offer superior performance and are more efficient than FPGAs. Factors like faster speed and the ability to layer multiple functionalities onto a single chip make ASICs outperforms FPGAs. 12. Why do we need FPGA?Why Use an FPGA? ... FPGAs are particularly useful for prototyping application-specific integrated circuits (ASICs) or processors. An FPGA can be reprogrammed until the ASIC or processor design is final and bug-free and the actual manufacturing of the final ASIC begins. Intel itself uses FPGAs to prototype new chips.13. Is ASIC a CPU?CPUs and microprocessors are the same thing. ASIC is just a general term for a microchip. CPUs are technically ASICs, but much simpler devices can be implemented on an ASIC too.14. What is the most preferred FPGA variant?Verilog is currently the most popular. Verilog creates a level of abstraction to hide away the details of its implementation. Verilog has a C-like syntax, unlike VHDL.15. What is ASIC technology?An application-specific integrated circuit (ASIC /ˈeɪsɪk/) is an integrated circuit (IC) chip customized for a particular use, rather than intended for general-purpose use. ... ASIC chips are typically fabricated using metal-oxide-semiconductor (MOS) technology, as MOS integrated circuit chips. 16. When should ASIC and FPGA devices be used?If your application requires constant bug fixes, feature and design changes, and software flexibility, then FPGAs may be the right solution. If your end application requires high performance, smaller device footprint, and significantly lower power consumption, then ASICs are your best bet. 17. How does an ASIC work?ASICs allow miners to use hardware made specifically for Bitcoin or other SHA-256 algo coins. An ASIC has benefits over CPU, GPU and FPGAs due to being designed for one specific task. They are able to mine Bitcoin at a higher hash rate (speed of processing transactions) than CPUs, GPUs and FPGAs.18. Why use an FPGA instead of a CPU or GPU?This is where FPGAs are much better than CPUs (or GPUs, which have to communicate via the CPU). With an FPGA it is feasible to get a latency around or below 1 microsecond, whereas with a CPU a latency smaller than 50 microseconds is already very good. Moreover, the latency of an FPGA is much more deterministic. 19. Why is ASIC needed?ASICs are designed specifically for one client to provide a function required by the client's end product. For example, a cell phone company may design an ASIC to combine the display backlight controller with the battery charging circuit into a single IC in order to make the phone smaller.20. What is better ASIC or GPU?In short: ASICs are best for mining Bitcoin, Litecoin, Dash, and coins that are based off these algorithms. GPUs are best for mining Ethereum, Monero, Ravencoin, and coins based off those algorithms. Note: Over time all of these coins will produce less thanks to halvings which cut the reward for mining blocks in half.You May Also LikeDiscussion on the influencing factors of clock in FPGA designNew SoM Combination Design Based on Processor and FPGA: FPGA and Processo

In addition to magnetic element design, feedback network design is also the least known and very troublesome work of switching power supply. It involves analog electronic technology, control theory, measurement and computing technology and other related issues.CatalogI Frequency response1.1 Basic concept1.2 Frequency response of basic circuits1. 3 Characteristics of LC filter circuitII Time-domain response of basic circuits2.1 Step-function signal2. 2 Step response of single time constant2. 3 Step response of LC circuitIII PluralIV Complex functionV Exchange C and LThe purpose of switching power supply loop design is to achieve the required output (voltage or current) accuracy within the range of input voltage and load variation, and meanwhile, makes equipment to work stably under any circumstances. What’s more, achieve fast response and small overshoot when load or input voltage changes. At the same time, it can reduce the low frequency pulsation component and the switch ripple and so on.To better understand the feedback design method, the basic knowledge of frequency characteristics, negative feedback and operational amplifier in analog circuits is reviewed importantly. Here the basic design method of feedback compensation is discussed with the example of forward converter. It also introduces how to test the open loop response by using analyzer HP3562A, and then design and correct the network according to the test characteristics and verify the design results. Finally, introduce the simulation test.I Frequency responseIn electronic circuits, reactance (inductor and capacitor) elements are inevitable. For different frequencies, their impedance varies with frequency. Their electrical signals not only change in amplitude, but also in phase. The relation between output and input of sinusoidal signals with different frequencies is called frequency response.1.1 Basic conceptThe output-to-input ratio of the circuit is called a transfer function or gain. The relation between the transfer function and the frequency, that is, the frequency response can be represented by the following expression: G=(f)∠φ(f), while G(f) is the relation between the modulus (amplitude) of the transfer function and the frequency, which is called the amplitude-frequency response; ∠φ(f) is the relation between the phase difference of the output signal and the input signal and frequency, which is called the phase frequency response.The typical logarithmic amplitude-frequency response is shown in Fig. 1, and Fig. 1 (a) is the amplitude-frequency characteristic. It is drawn on the logarithmic coordinate with logarithmic frequency f as the transverse coordinate, and the longitudinal axis gain is represented by 20logG(f). Fig. 1 (b) is the phase frequency characteristic, and the vertical axis represents the phase angle φ on the single logarithmic coordinate with logarithmic frequency f as the transverse coordinate. This diagram is called Potier graphs.Fig. 1 Potier graphsIn terms of amplitude-frequency characteristics, there is a frequency range in which the gain is basically constant, and when the frequency is higher or below than a certain frequency, the gain will decrease. When the high frequency increases, if the gain is lower than the constant part of the 3dB, the frequency is called the upper limit frequency or the upper limit cut off frequency, representing by fH, while the frequency is larger than the cut-off frequency is called the high frequency region. At low frequency, when the gain is lower than the constant part of 3dB, the frequency is called the lower frequency or the lower rate limit, representing by fL, where the frequency is lower than the lower cut-off frequency is called the low frequency region. Between the high-frequency cut-off frequency and the low-frequency cut-off frequency is called the intermediate frequency region. In this area, The gain is basically unchanged. The definition of it: BW=fH-fL1.2 Frequency response of basic circuits1.2.1 High frequency responseFig. 2 High - frequency responseIn the high-frequency region, the circuit that affects the high-frequency response of the system (circuit) is shown in Fig. 2. Taking Fig. 2(a) as an example, the ratio of output voltage to input voltage decreases with the increase of frequency, and meanwhile the phase lags.Using complex variables to obtainAs for the actual frequency, s=jw=j2πf , making(F-0)The high-frequency voltage gain of the circuit can be obtained: The relationship between the frequency and phase angle, and the mode (amplitude) of the gain in the high frequency region are obtained:The logarithmic amplitude-frequency is(F-1)1.2.1 Amplitude-frequency response1) when f<<fH,The gain value is 1, a horizontal line at the horizontal coordinates;2) when f>>fH,It can be seen that for the logarithmic frequency coordinate, the upper formula can be represented by an oblique line, the slope is -20dB/ tenth frequency (- 20dB/dec), and intersects with the 0dB line at f=fH, so fH is called turning frequency. When f=fH, that is  , the high frequency response takes the 0dB line and-20dB/dec as the asymptote, and the maximum difference at the turning frequency is-3dB. The amplitude-frequency characteristic is shown in Fig. 3(a)Fig. 3 High - frequency potier diagramWhen the frequency is equal to the turning frequency, the capacitor reactance is exactly equal to the resistance. When the frequency increases continuously, the impedance of capacitor C decreases by-20dB/dec, that is, the frequency increases by 10 times and the capacitive reactance decreases by 10 times, so the output attenuates with-20dB.1.2.2 Phase-frequency characteristic The relationship between phase and frequency can be made in the following ways according to formula (F-2).- When f<<fH, φ closes to 0 ° , getting a straight line.- When f>>fH, φ closes to 90 ° , getting a straight line.- When f=fH, φ=45 °.- When f=0.1fH, and f=10fH, φH is -5.7 °and -84.3 °respectively, so the slope is represented approximately by 45/dec oblique line. The phase frequency characteristics are shown in the following figure.Fig. 3 High - frequency potier diagramFrom the amplitude-frequency and phase-frequency, it can be seen that when the frequency increases, the gain of the circuit becomes smaller and the phase lag becomes larger. When the phase reaches 90 °, the gain is 0. Both amplitude-frequency and phase-frequency characteristics are determined by upper frequency fH. It can be seen from formula (F-0) that the upper cut-off frequency is determined by the time constant (RC) of the circuit. If the time constant L /R of Fig. 2(b) is equal to the time constant RC of Fig. 2(a), the porter diagram of Fig. 2(b) circuit is exactly the same as that of Fig. 2(a).As can be seen from Fig. 3, the high frequency signal attenuates greatly, while the low frequency signal is preserved. Therefore, this circuit is also called a low-pass filter. For Fig. 2(a) circuits, if the time constant is much larger for the time studied, that is, the resistance and capacitance values are large  Uo=Uc，From  it can get This is an integrator. It can be seen that the same circuit has different functions for different research purposes.1.2.3 Low Frequency CharacteristicWe study the characteristics of the two circuits in the low frequency region shown in Fig. 4. Fig. 4 Low -frequency regionUsing the complex variables, from Fig. 5 (a), Fig. 5 Low - frequency potier diagramwe can getAccording to actual frequency and s=jw, makingGettingThus the gain (mode) and phase angle of the low frequency region of the circuit are respectively:Use the linear approximation method which is similar to the high frequency response, the potier diagram of the low frequency response can be drawn, as shown in Fig. 5. The fH in the diagram is the lower limit frequency, that is, the low turning frequency. Below the turning frequency, the gain of the circuit decreases with the decrease of the frequency, and the characteristic slope is 20dB/dec. When the phase reduces with the frequency, using the forward input phase. Maximum advance 90 °, gain 0 (- ∞, dB).The lower limit transition frequency is also related to the circuit time constant RC (L/R). If the time constants of Fig.4 (a) and Fig.4 (b) are the same, their potier graphs are identical.It can also be seen from Fig.5 that the circuit attenuates the low frequency signal, while the high frequency signal passes smoothly due to the reduction of capacitance. So this circuit is also called a high-pass filter. For Fig. 4(a), when the time constant of the Fig. 4(a) circuit is much smaller than the time interval we studied, the output obtains the variable input signal, then the circuit is a differential circuit.1. 3 Characteristics of LC filter circuitFig. 6 Frequency characteristic of LC filter circuitIn the switching power supply, the forward output filter (Fig. 6) is a LC network with a load resistor in parallel with the output capacitor, and the load resistor can be changed from a certain value (full load) to infinity (no load). For Fig. 6, we can also use complex variables to getAccording to actual frequency and s=jw, makingGetting (F-2)The characteristic impedance of the circuit is, at small range of f close to f0,, making , so The gain amplitude-frequency and phase-frequency characteristics are as follows respectively:(F-3)The Potier diagram of the LC filtering circuit can be made by the expressions (F-3), as shown in Fig.. When f <f0, the formula (F-3) tends to 1, that is 0db, φ≈ 0°; When f >f 0, the second term in the denominator (F-2) is much larger than the other two, the inductive reactance is increased by 20dB/dec, the capacitive reactance by 20dB/dec is decreased, the load impedance is far greater than the capacitive reactance, and the amplitude-frequency is decreased by 40dB/dec, φ tends to -180 °. When f is close to f0, different D values and amplitudes do not increase. The greater D value is equivalent to the light load, that is circuit underdamping, the higher the amplitude. With the increase of the load, the equivalent load resistance decreases, the D value decreases, and the peak value of lifting decreases. When D=1, at critical damping, amplitude-frequency increases slightly from low frequency to f0, at f=f0, it returns to 0dB, and when f >f0, the gain tends to -40dB/dec. When D < 1, the damping is equivalent to full load or overload. In the vicinity of f →f0, the amplitude doesn’t raise, but also attenuates with the increase of frequency, and the slope of attenuation is about 20 times of f0. The relationship between phase shift and f/fc and different D values is shown in the Fig. 8 of amplitude-frequency reaching-40dB/dec. It can be seen that the phase difference between the output and the input is 90 °at the turning frequency point f 0, regardless of the D value. For the high underdamped filter (Ro > 5Zo), the phase frequency characteristic changes rapidly with the frequency. For Ro=5Zo, when frequency at 1.5f0, the phase shift is almost 170 °. But in the circuit with gain slope of-20dB/dec, it is impossible to produce phase shift greater than 90 °, and the phase frequency characteristic changes with the frequency. The change rate of phase shift of in Fig. 8 is much lower than that of -90 °/dec in Fig. 8.Fig. 7 Frequency amplitude of LC filter circuitFig. 8 Phase frequency of LC filter circuitIf the output capacitance in Fig. 7. has ESR , is equivalent series resistor Resr. It is generally very small and the low frequency characteristic will not be affected by 1/ωC<<Resr, in low frequency band. When the frequency increases to At this time  ,the phase is raised by 45°. As the frequency continues to rise, the output filter circuit becomes a LResr circuit. The LC filter attenuates from-40dB/dec to-20dB/dec after the frequency fesr, and the phase shift tends to lag by 90 ° instead of 180 °. This means that the capacitance of the ESR provides a zero point.II Time-domain response of basic circuitsThe circuit analysis includes steady state analysis and transient analysis. The frequency response of the amplitude and phase of the circuit is analyzed with sine wave as the basic signal, which is the steady-state response. This method is called frequency domain analysis method.Another method of circuit analysis is transient analysis. The step-function signal is used as input signal to study the variation of circuit output with time, which is called step response. It is judged by the rising time of the waveform and the flat-top drop size. It's called time domain analysis.2.1 Step-function signalThe graph represents a step voltage that can be represented as:It can be seen that the change rate of step signal waveform is infinite, but it is a constant during the conversion. From the point of view of frequency analysis, the extremely fast rate of change includes harmonic components from DC to very high frequency. Whether the output of the circuit can repeat the waveform of the input signal: the rising time of the output reflects the high frequency response of the circuit, while the flat top drop reflects the low frequency response of the circuit.2. 2 Step response of single time constantLet's study the step response of Fig. circuit. The step response is represented by the rise time tr and the flat-top landing δ. Fig. 9 Step response of single time constantRise time trWhen the step signal is added to the input of Fig. (a) circuit, according to the general law of RC circuitU0-initial value;  U∞-terminal value; τ= RC- time constant. The capacitance initial voltage U0  is zero.In the formula τ = L/R, Ui is the voltage value of the flat top part of the step signal. The relation between Uo/Ui  and time is shown in Fig. 10. The three elements of RC circuit: initial value, final value and time constant. The input rises to the final value in a very short time, and the output voltage changes with time exponentially, which takes a period of time to reach the final value. This phenomenon is called frontier distortion. The interval between 10% of the output end value and 90% of the final value is generally defined as the rising time tr.Fig. 10 The relation between Uo/Ui and tAs can be seen from the expressions (6-18), when t=t1according to the same principle, when t＝t2Because ofSo the rise timeHigh frequency response of circuit f 1/(2πRC)H，gettingTherefore, the rise time is inversely proportional to the upper bound frequency. The higher the is, the smaller the rise time tr is and the lower the front distortion is. For example, the bandwidth of a circuit is 1MHz, and the step-up time is tr=0.35 rt μs. We use Fig. (a) to study flat-top landing. When step input, the output isThe relationship between and time is shown in Fig. 11. If the time tp is small than τ, the output voltage will still decrease according to the exponential law, though the input voltage is invariable, and the decreasing speed is related to the time constant. This phenomenon is called flat-top descent. Fig. 11 Flat-top descentBecause of tp < τ, it can be approximately obtained:Considering that fL=1/ (2πRC), then getsIt can be seen that the flat-top drop δ is proportional to the lower limit frequency fL, and the lower the fL , the smaller the flat-top fall. In switching power supply, the sudden change of load and input power supply voltage is also a step-by-step response. In the above research, the system is still in the linear state, but in the switching power supply, there are high gain amplifiers, under the action of the step signal, the system usually enters the nonlinear state, the large signal response is often lower than the small ones.2. 3 Step response of LC circuitFig. 12 Step response of LC circuitThe LC circuit is shown in Fig. 12. If the circuit loss resistance is zero,  initial voltage of the inductance initial current and capacitance are zero, under the action of step-up signal, getting the formulas are as follows:Ui as step input signal; resonant angular frequency of LC circuitCharacteristic Impedance of resonant CircuitThe peak value of inductance current isDifferent initial values, excitation and circuit conditions, initial and final values of the waveform amplitude are different, but the phase relationship is fixed.Note: plural conceptIII PluralThe complex number is composed of real part and imaginary part, that is,, gettingSince a complex number is composed of two numbers, we can use the x axis as the real number and the y axis as the imaginary axis, as shown in Fig 13. Redraw the Fig. 13 as Fig. 14, and you can see that the complex number can be expressed in two quantities: one is the distance to the coordinates (0,0) , and the other is the angle  from the counterclockwise to the point . The value r is called the modulus of the complex number, and the angle φ is called the amplitude angle of the complex number.Fig. 13 Complex graphic methodFig. 14 Expressing complex number by distance and angleIn electricity, we naturally think of using complex numbers to express values and phases. For example, if you represent a sinusoidal quantity of electricity, the sine is projected on the imaginary axis with the coordinate distance, and the cosine is projected on the real axis, so a complex number can also be represented as (F-4)According to Euler's formula The upper form can be solved as  (F-5), or simplified to (F-6)It can be seen that a complex number can be expressed in the following ways: (F-4) is a complex cartesian coordination, (F-5) is exponential, and (F-6) is polar coordinate. The three can be converted to each other. The complex number can be added or subtracted by cartesian coordination, and the multiplication and division operations by the exponential or the polar coordinates.According to the above mentioned formulas, if φ==90°, soAny phasor multiplied by j, phase rotation 90°: + represents counterclockwise rotation; - represents clockwise rotation. If the virtual axis is j, times j, then rotates to the solid axis to change to -1, then , so is the imaginary unit.IV Complex functionThe instantaneous amplitude and phase can be expressed by a complex number. If a sinusoidal quantity is expressed, the complex number in the circuit is frequency dependent. There are two aspects of interest in steady-state design: what are the parameters of a function that are zero? And where is the function infinite? These two cases represent the zeros and poles of the function respectively.For example It is obvious that x=2 in this function while phase is zero, that is, the complex amplitude is 2, the phase is 0, in other words, the real part is 2, and the imaginary part is 0 (Fig. 15), and the x=3 function becomes infinite. Its complex image value 3 and phase value 0 as another example, we can see that the capacitance has frequency dependent complex 1/sC (s as an complex variable, frequency-dependent), while the inductance is sL. Fig. 15 shows the switching power output filter (capacitor has ESR, inductor has coil resistance, not considered here). Form a voltage divider with an output to input ratio of Fig. 15 Complex impedance of inductor and capacitorThis function will not be zero, but when, that is, there are two poles. The two poles appear at the resonant frequency point and the phase angles are 90 °and 270 °(pure imaginary number, no real part, as shown in Fig. 16 ). Of course, the physical meaning here is that the LC network resonates at this frequency and the output is amplified infinitely at this frequency. In fact, there is always resistance in the actual circuit, so the magnification is not infinite, that is, the two poles are not on the virtual axis and the real part is not zero.Fig. 16 Poles of LC resonant frequencyV Exchange C and LFor capacitive currentIf Us=Uest，the voltage is a sine wave [because of ]，we can getGetting the resistance is: In the definition of Laplace transformation, we do not have to actually solve the integral because the integral is implicit in solving the differential equation. Similarly, we can get the inductance impedance: Similarly, use  to replace  to get: So the resistance is Z=sL

The transformer is an essential part of electrical equipment. So it is necessary to know and master the basic knowledge of it. Is a necessary skill of every electric design. Catalog I. What is a Transformer? II. How does Transformer Works? III. What types of transformer are there? IV. What are the components of the transformer? V. What are the losses of transformers in operation? How to reduce them? VI. What is the nameplate of the transformer? What are the main technical   data on the nameplate? VII. How to choose a transformer? VIII.Why transformer cannot run when overload? IX. What kinds of tests should be done for transformers in operation? FAQ I. What is a Transformer? The transformer is a device that uses the principle of electromagnetic induction to change the AC voltage. The main components are primary coil, secondary coil, and core (magnetic core). The main functions are voltage conversion, current conversion, impedance transformation, isolation, voltage stabilization (magnetic saturation transformer), and so on. It can be divided into a power transformer and special transformer (furnace transformer, rectifier transformer, power frequency test transformer, voltage regulator, mine transformer, audio transformer, intermediate frequency transformer, high-frequency transformer, impulse transformer, instrument transformer, electronic transformers, reactors, voltage, and current transformer, etc.) The role of the core is to strengthen the magnetic coupling between the two coils. In order to reduce the eddy current and hysteresis loss in the iron, the iron core is formed by the superposition of the painted silicon steel sheet; there is no electrical connection between the two coils, and the coils are wound by insulated copper wire (or aluminum wire). One coil connected to the AC power supply is called the primary coil (or the primary coil) and the other coil is the secondary coil connected to electrical appliances. The actual transformers are very complicated, so there may be problems that exist to concern, such as copper loss (coil resistance heating), iron loss (core heating), magnetic flux leakage (air-closed magnetic induction line), and so on.  To simplify the discussion, an ideal transformer is introduced. An ideal transformer requires some necessary conditions: ignoring the flux leakage, ignoring the resistance of the primary and secondary coils, ignoring the loss of the iron core, and ignoring the no-load current (the current in the primary coil which supplies the secondary coil). For example, the power transformer is close to the ideal condition when it is running at full load (the output with a rated power of the secondary coil). The transformer is a static electrical appliance made by the principle of electromagnetic induction. When the primary coil of the transformer is connected to the AC power supply, the core produces an alternating flux, which is represented by φ. The φ in the primary and secondary coil is the same, and φ is also a simple harmonic function, and φ = φ msinωt. According to Faraday's law of electromagnetic induction, the induction electromotive force in the primary and secondary coils is e1=-N1d φ/dt, e2=-N2d φ /dt. N1, N2 is the number of turns of the secondary coil. From the diagram, we can see that U1=-e1, U2=e2(the primary coil physical quantity is represented by the subscript 1, the secondary coil physical quantity is indicated by the subscript 2), and the complex-effective value is U1=-E1=jN1 ω Φ, U2=E2=-jN2 ω Φ, and makes transformer ratio k=N 1 /N 2. From the upper formula, we can get U1 /U2=-N1 /N2=-k. that is, the voltage effective value of the transformer to that of two coils, which is equal to its coil-voltage ratio, and the phase difference of the voltage of two coils is π. Further More Based On Above Mentioned U1/U2=N1/N2 Under the condition that the no-load current can be neglected, there is I1 /I2=-N2 /N1, that is, the effective value of the coil's current is inversely proportional to the number of turns, and the phase difference is π. On the contrary, under the condition of no-load current, I1/ I2=N2/N1 The power of the ideal transformer is equal to that of the subsoils, that is P1=P2. It shows that the ideal transformer itself has no power loss. But there is always a loss in the actual transformer, and its efficiency is η= P2 /P1, for example, although power transformer efficiency is very high, can reach over 90%, still has a little loss. In an AC circuit, the equipment that increases or decreases the voltage is called a transformer. The transformer can transform any voltage into the value we need at the same frequency to meet the requirements of transmission and distribution. For example, the power generated by a power plant has a lower voltage level, which must be increased the voltage to transmit to a far distance, and the power area must reduce the voltage to a suitable voltage level for power equipment and daily use. II. How does Transformer Works? This video gives a detailed animated illustration on the working of electrical Transformers. Here the basic working principle and construction of transformer, step-up transformer, step-down transformer, transformer winding and core construction are well illustrated. Transformers are based on electromagnetic induction. It consists of an iron core made of silicon steel sheet (or silicon steel sheet) and two sets of coils around the core. The core and the coil are insulated from each other without any electrical connection. The coils connected to one side of the transformer and the power supply are called primary coils (or primary sides), and the coils that connect transformers and electrical equipment are called secondary coils (or secondary sides).  When the primary coil of the transformer is connected to the AC power supply, the changing magnetic field line in the core appears. Because the secondary coil is wound on the same iron core, the magnetic field line cuts the secondary coil, and the inductive electromotive force must be generated on the secondary coil, finally, the voltage at both ends of the coil generated. Because the magnetic line is alternating, the voltage of the secondary coil is also alternating. And its frequency is exactly the same as the frequency of the power supply. It is proved by the theory that the voltage ratio between the primary coil and the secondary coil is related to the turns of coils. It can be expressed as follows: Primary coil voltage / secondary coil voltage = primary coil turns / secondary coil turns, the higher the number of turns, the higher the voltage. Therefore, it can be seen that the turns of the secondary coil are less than the primary coils, that is, a step-down transformer, otherwise, it is a step-up transformer. III. What types of transformer are there? According to the number of phases, there are single-phase and three-phase transformers;  according to thefunction, there are power transformers, special power transformers, voltage regulating transformers, measuring transformers (voltage transformers, current transformers), small power transformers (for small power equipment), safety transformers;  according to the structure, there are core type and shell type; according to the coil, there has double winding and multi-winding transformers, auto-transformer; according to the cooling mode, oil-immersed type and air-cooled type transformers. IV. What are the components of the transformer? Transformer components are mainly composed of iron core, coil, also have other parts, such as oil tank, oil pillow, insulating sleeve and splice, etc. What’s the function of transformer oil? The functions of transformer oil are:  (1) insulation;   (2) heat dissipation;  (3) elimination of arc. What is autotransformer? The autotransformer has only one set of coils, and the secondary coils are tapped from the primary coils, and its electricity can transmitted. It not only has electromagnetic induction, but also the transmission of electricity. There are fewer silicon steel sheets and fewer copper wires in this kind of transformer than in ordinary transformers, often used to voltage regulator. How voltage regulator works? The voltage regulator is constructed the same as the autotransformer, but the iron core is made into a ring coil. The secondary coil tap uses a sliding brush contact to make the surface of the ring along the contact slip in a circular way to achieve voltage regulation smoothly. What is the current relationship between the primary coil and the secondary coil of the transformer? When the transformer operates with load, the current change of secondary coil will cause the corresponding change of primary coil current. According to the principle of magnetic potential balance, it is deduced that the current of the primary and secondary coil is inversely proportional to the number of turns of the coil, the current is small with more turns, and the current with less turns is large. The following formula can be expressed: primary coil current / secondary coil current = secondary coil turns / primary coil turns. What is the voltage change rate of a transformer? The voltage change rate of the voltage regulator is one of the main indexes of transformer performance. When the transformer supplies power to the load, the voltage at the load end of the transformer will inevitably decrease. Comparing the reduced voltage value with the rated voltage value, the percentage is the rate of voltage change. It can be expressed by the formula: voltage change rate = [(secondary rated voltage-load terminal voltage) / secondary rated voltage] ×100%. Generally, for the normal power transformer, when connected to the rated load, the voltage change rate is 4% to 6%. How to ensure that the transformer has a rated voltage output? Too high or too low voltage will affect the normal operation and service life of the transformer, so the voltage must be adjusted. The method of voltage regulation is to draw out several taps in the primary coil and connect them to the tap beginning, which changes the number of turns of the coil by turning the contact. In addition, the required rated voltage can be obtained by rotating the position of the tap switch. It also needs to note that voltage regulation usually occurs after the load of the transformer is cut off. What kind of small transformers are usually used? Where are they applied? Small transformers refer to single-phase transformers with a capacity below 1k VA, mostly used as power transformers for electrical equipment control, electronic equipment and safe lighting equipment. V. What are the losses of transformers in operation? How to reduce them? The loss of transformer in operation includes two parts. (1) One is caused by the iron core. When the coils are electrified, the magnetic field lines are alternating and cause eddy current and hysteresis loss in the core.  (2) Another loss is caused by the resistance of the coil itself. When the primary and secondary coils of the transformer have current passing through, some electrical energy may lose. The sum of iron loss and copper loss is the transformer loss, which is related to transformer capacity, voltage, and equipment utilization. Therefore, in the selection of transformers, the capacity of the equipment and the actual usage should be as consistent as possible, in order to improve the utilization rate of the equipment, pay attention not to make the transformer lies in light load operation. VI. What is the nameplate of the transformer?  The nameplate of the transformer should indicate the transformer's performance, technical specifications, and use occasions to meet the needs of the user. The main technical data usually selected are as follows: (1) The number of rated capacity. The output capacity of the transformer is rated. For example, the rated capacity of a single-phase transformer is Uline × I line, and the capacity of a three-phase transformer is also the U line × I line. (2) Rated voltage volts. Indicate the terminal voltage of the primary coil and the secondary coil (when the load is not attached). Note that the terminal voltage of the three-phase transformer refers to the line voltage U-line value. (3) Rated current amperes. It means LineI current value that allows long-term passage of primary and secondary coils at rated capacity and allowable temperature rise. (4) Voltage ratio. It is the ratio between primary coil rated voltage and secondary coil rated voltage. (5) Line connection mode. Single-phase transformers have only a set of coils of high and low voltage, only for single-phase use, and three-phase transformers have Y/△type. In addition to the above technical data, there are transformer rated frequency, phase number, temperature rise, impedance percentage of the transformer, etc. VII. How to choose a transformer?  First of all, it is necessary to investigate the power supply voltage of the place where the electricity is used, the actual power load of the user, and the conditions of the place where it is located, and then select one by one according to the technical data indicated by the nameplate of the transformer, generally from the capacity and voltage of the transformer. Considering the current and environmental conditions, the capacity selection should be based on the capacity, nature, and service time of the user's power equipment to determine the required load, and then select the transformer capacity. In normal operation, the power load of the transformer should be about 75% ~ 90% of the rated capacity of the transformer. When the actual load of the transformer is less than 50%, the small capacity transformer should be used, and the large transformer should be replaced immediately if the rated capacity of the transformer is greater than that of the transformer. At the same time, when selecting the transformer to determine the primary coil voltage of the transformer according to the line power supply and the voltage value of the secondary coil according to the electrical equipment, it is best to select the low-voltage three-phase four-wire power supply system. This can provide a power supply for the entire operation. For the selection of current, attention should be paid to that the load can meet the requirements of the motor when it starts (because the starting current of the motor is 4 ~ 7 times larger than that of the sinking operation). VIII. Why transformer cannot run when overload? Overload operation refers to the transformer operating in excess of the currency specified on the nameplate. Overload is divided into normal overload and accident overload. The former refers to the increase of power consumption under the normal power supply, and it often makes transformer temperature rise, impels transformer insulation to age, and reduces service life. Therefore, transformer overload is not allowed. In special cases, the overloading of transformers in a short period of time should not exceed 30% of the rated load in winter, and not more than 15% in summer. For the latter, the accident overload and allowable time requirements are as follows: Multiple of Rated LoadReasonable Time of Overload Multiple of Rated Load Reasonable Time of Overload Indoors Outdoors 1.30 2 hours 1 hour 1.60 30 minutes 15 minutes 1.75 15 minutes 8 minutes 2.00 7.5 minutes 4 minutes IX. What kinds of tests should be done for transformers in operation? In order to ensure the normal operation of the transformer, the following tests should be carried out regularly. (1) Temperature test. Whether the transformer is running normally, the temperature is very important. The regulations stipulate that the upper oil temperature shall not exceed 85℃(that is, the temperature rise is 55℃). General transformers are equipped with special temperature measuring devices. (2) Load measurement. In order to improve the utilization rate of transformers and reduce the loss of electric energy, it is necessary to determine the real power supply capacity of transformers in the operation of transformers, the measurement is usually carried out during the current peak period and is measured directly with a clamp ammeter. The current value shall be 70%~ 80% of the rated current of the transformer. (3) Voltage measurement. The regulation requires that the voltage range should be within ±5% of the rated voltage. If beyond this range, taps should be used to adjust the voltage to reach the specified range. Voltmeters are generally used to measure the terminal voltage of the secondary coil and the terminal voltage of the user. (4) Insulation resistance measurement. In order to keep the transformer in normal condition, insulation resistance must be measured to prevent insulation aging and accidents. When measuring the transformer, the transformer should stop running and the insulation resistance of the transformer should be measured by using the tramegger. The resistance measured should not be less than 70 percent of the previously measured value. When using tramegger, the low-voltage coil may adopt a voltage grade of 500 volts. FAQ 1. What is the use of transformer? Transformers are employed for widely varying purposes; e.g., to reduce the voltage of conventional power circuits to operate low-voltage devices, such as doorbells and toy electric trains, and to raise the voltage from electric generators so that electric power can be transmitted over long distances. 2. What are the 3 types of transformers? There are three primary types of voltage transformers (VT): electromagnetic, capacitor, and optical. 3. What is the basic principle of transformer? A transformer consists of two electrically isolated coils and operates on Faraday's principal of “mutual induction”, in which an EMF is induced in the transformers secondary coil by the magnetic flux generated by the voltages and currents flowing in the primary coil winding. 4. Does a transformer convert AC to DC? A transformer is built to transfer the energy from one circuit into another circuit by way of magnetic coupling. ... An alternating current creates a magnetic flux in the core on its way through the first winding, inducing the voltage in the others. It can convert high and low voltages, it cannot convert AC to DC. 5. What are the main parts of transformer? There are three basic parts of a transformer: a. an iron core which serves as a magnetic conductor, b. a primary winding or coil of wire and. c. a secondary winding or coil of wire. 6. What are the classification of transformer? Depending upon the type of construction used, the transformers are classified into two categories viz.: (i) Core type, and (ii) Shell type. Depending upon the type of service, in the field of power system, they are classified as: (i) Power transformers, and (ii) Distribution transformers. 7. Can a transformer work on DC? As mentioned before, transformers do not allow DC input to flow through. This is known as DC isolation. This is because a change in current cannot be generated by DC; meaning that there is no changing magnetic field to induce a voltage across the secondary component. 8. How do you convert a transformer? This conversion is made by winding two separate conductors around a common iron core. Applying an alternating voltage to the primary conductor produces current which sets up a magnetic field around itself. This is known as mutual inductance. 9. What are two components of no load current in transformer? The no-load current of a transformer consists of two components: The Magnetization Current iM is the current required to produce the flux in the transformer core. The Core-loss Current ih+e is the current required to make up for hysteresis and eddy current losses. 10. Which type of transformer core is most efficient? SHELL CORE. The most popular and efficient transformer core is the SHELL CORE, as illustrated in figure (4). As shown, each layer of the core consists of E- and I-shaped sections of metal. These sections are butted together to form the laminations. 11. What is the power factor of transformer? The power factor of a distribution transformer is between (0.75 to 0.80) when secondary is connected to u.p.f loads. 12. Why do we need Transformers? Transformers help improve safety and efficiency of power systems by raising and lowering voltage levels as and when needed. They are used in a wide range of residential and industrial applications, primarily and perhaps most importantly in the distribution and regulation of power across long distances. 13. What is the difference between a step up transformer and a step down transformer? A transformer that increases the voltage from primary to secondary (more secondary winding turns than primary winding turns) is called a step-up transformer. Conversely, a transformer designed to do just the opposite is called a step-down transformer. 14. Are transformers dangerous? There is no established evidence that the exposure to magnetic fields from powerlines, substations, transformers or other electrical sources, regardless of the proximity, causes any health effects. 15. Why transformer rating is in kVA not in kW? Copper losses (I²R) depends on current which passing through transformer winding while Iron losses or core losses or Insulation losses depends on Voltage. ... That's why the transformer rating may be expressed in VA or kVA, not in W or kW.

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In this article, you will learn what is AVR microcontroller, what are its features, how to choose a suitable AVR microcontroller, and how to program AVR microcontroller in software and so on. Catalog I. What is a AVR Microcontroller? II. AVR Microcontroller Features III. Selection of AVR Series Single-chip Microcomputer IV. AVR Microcontroller Application Field V. Introduction to the experimental tools and equipment used in AVR VI. AVR Microcontroller Programming Software FAQ I. What is AVR Microcontroller? AVR microcontroller is an enhanced 8-bit and built-in Flash RISC order set developed by ATMEL. Compared with CISC, RISC is not just to reduce the command simply, but make the structure of the computer more simple and reasonable to improve the speed of the operation. The design absorbs the advantages of the 8051 and PIC microcontroller and has the ability to execute one instruction in a single clock cycle. The speed can reach 1Mips/MHz. AVR microcontrollers are widely used in the outside devices of the computers, industrial real-time control, instrumentation, communication equipment, home appliances, and other fields. This vedio shows you how to build your own AVR development board and how to use it in your projects. The hardware structure of AVR adopts a compromise strategy of 8-bit and 16-bit computer, that is, the local register memory stack (32 register files) and the single high-speed input/output scheme (i.e. input capture register, the output compares matching registers and corresponding control logic) are adopted, improving the execution speed of instruction, overcoming the bottleneck phenomenon, and enhancing the function. At the same time, it reduces the cost of external equipment management, simplifies the hardware structure, and reduces the cost. Therefore, the AVR microcontroller is a high-performance-price single-chip microcomputer, which has achieved an optimized balance in hardware/software development, speed, performance, and cost. The introduction of the AVR microcontroller breaks this old design pattern completely, abolishes the machine cycle, and gives up the complex instruction computer (CISC) to pursue the instruction complete method; Reducing instruction set, taking words as the unit of instruction length, arranging the rich operands and opcodes in one word (the majority of single-cycle instructions in the order set are the same), and the reference period is short and the instruction can be prefetched, realizing flow operation, so you can execute instructions at high speed. Of course, high reliability must be required. II. AVR Microcontroller Features 1. High-quality embedded Flash program memory, can be repeatedly written and erased, supporting ISP and IAP, which is easy to have product debugging, development, production, update. Long service-life EEPROM, can save key data for a long time and avoid power loss. High-capacity RAM in chips supports the development of system programs in high-level languages. 2. High speed, low power consumption, with SLEEP (power saving when sleeping) function. Each instruction can be executed at 50ns/ 20MHz, while power consumption is between l~2.5mA (typical power consumption, when WDT turned off, is 100nA), AVR (with prefetching instruction function) based on Harvard structure concept. That is, there are different memories and buses for program storage and data, when an instruction is executed, the next instruction is pre-removed from the program memory. This allows instructions to be executed within each clock cycle. The AVR microcontroller can operate at a wide voltage (2.7V~5V), has the strong anti-jamming ability, and reduces the general 8-bit computer software anti-interference design and hardware usage. 3. All the I/O lines of the AVR single-chip computer have an adjustable pull-up resistor. The input and output characteristics of parallel I/O port are similar to those of PIC's HI/LOW output and three-state high impedance H1-Z input, also be set similar to the 8051 series of internal high resistance as input function. It can be set as an input/output or can be set as high resistance input initially. So that I/O resources are flexible, powerful, and fully utilized. AVR's I/ O can accurately reflect the input/output of I/O. 4. AVR microcontroller has a variety of independent clock dividers for URAT, IIC, SPI. The Prescaler with up to 10 bits when matching with the 8 / 16-bit timer, can set the frequency division coefficient through software to provide a variety of timing times. The timer/counter (single) in the AVR microcontroller can be counted bidirectionally to form a triangle wave, then matched with the output comparison matching register, the output PWM of pulse width modulation with variable duty cycle, variable frequency, and variable phase square wave is generated. 5. For industrial products, with high current (irrigation current) lO=20mA~40mA (single output), can directly drive SSR or the relay. The built-in watchdog timer (WDT) is used to avoid the faulty program and improve the anti-interference ability of the product. 6. Superfunctional streamlined instruction. There are 32 general working registers (equivalent to 32 accumulators in 8051 single-chip computers), which overcomes the data processing problems caused by the single accumulator. 7. AVR microcontroller has analog comparator, I/O port can be used for A/D conversion, can form cheap A/D converter. 8. Byte-oriented high-speed hardware serial interface TWI and SPI. TWI is compatible with the I2C interface, with ACK signal hardware transmission and recognition, address recognition, bus arbitration, and other functions, It can realize all four kinds of multi-machine communication from one to another. SPI has the same function. It also looks like the 8051, AVR has multiple fixed interrupt vector entry addresses, so it can respond to interrupts quickly, and it will interrupt like PIC at the same vector address. 9. AVR microcontroller has an automatic power-up reset circuit, an independent watchdog circuit, low voltage detection circuit BOD, multiple reset sources (automatic up and down reset, external reset, watchdog reset, BOD reset). It can set up a delay operation program after running the system, enhancing the reliability of the system. And meanwhile, the AVR microcomputer has many power-saving sleep modes, wide voltage operation(2.7V-5V), strong anti-interference ability. So it is used widely in the electrical industry due to its advantages. 10. Enhanced high-speed synchronous/asynchronous serial port has the functions of generating checking code based on hardware, hardware detecting and debugging, two-stage receiving buffering, baud rate automatically adjusting position (when receiving), shielding data frame, and so on. They improve the reliability of communication and help write the program easily. It also makes up the distributed network and to realize the complex application of multi-computer communication system.  The function of the serial port is much more than the serial port of the MCS-51/96 microcontroller. In addition, the AVR single-chip microcomputer has a high-speed operation, and the interrupt service time is short, therefore, high baud rate communication can be realized. Serial asynchronous communication UART does not occupy timer and SPI transmission function, because of its high speed, it can work in a standard integer frequency, while baud rate can reach 576Ko11, with multi-channel 10-bit AID converter and real-time clock RTC. III. Selection of AVR Series Single-chip Microcomputer AVR microcontroller technology embodies a variety of devices (including FLASH program memory, watchdog, EEPROM, synchronous/asynchronous serial port, TWI/ SPI/ AID/ A/D converter, timer, counter, etc.) and various functions (enhanced reliability of reset system, reduced power-consumption and anti-interference sleep mode, various interrupt systems, timer/counter with input capture and match output, replaceable I/O port. It fully reflects the modern single-chip technology develops into the "on-chip" SoC system. AVR series microcontroller is complete, can be applied to different occasions. In order to make good use of it, it is necessary to know its classification based on different standards and functions. And here are introducing three grades and their models as examples. AVR microcontroller has three grades: Low-grade Tiny series: this type of microcontroller has Less memory, small in size, apt only for simpler applications, the applying model like Tiny11/12/13/15/26/28, etc.; Midrange-grade AT90S series: this microcontroller is used commercially for compound applications, it requires large program memory and also high speed, such as AT90S1200/2313/8515/8535, etc.; High-grade ATmega:  this type of microcontroller is the most popular one which has a good amount of memory up to 256KB, higher built-in peripherals, and fit for modest to difficult applications, the applying model like the ATmega8/16/32/64/128 (storage capacity is 8/16/32/64/128KB) and ATmega8515/8535. AVR device pins range from 8 to 64, with a variety of packages available. IV. AVR Microcontroller Application Field Air conditioning control panel Printer control board(PRCB) Intelligent meter Intelligent flashlight LED control screen Medical equipment GPS  V. Experimental tools and equipment used in AVR IC-CAVR6.31AC Language Compiler Integrated Development Environment(ATMEL AVR Studio) PonyProg2000 Download Software AVR Microcontroller Integrated Test Board AVR-JTAG Simulator Parallel Port Loader High Stability Power Supply Multifunctional TOP2004 USB Programmer PC VI. AVR Microcontroller Programming Software ICCAVR6.31AC Language Compiler ICCAVR6.31A is a C programming language compiler developed by ImageCraft for AVR MCU. It is a pure 32-bit with an integrated development environment, also consists of an editor and project manager. ICCAVR has been widely used because of its powerful function, simple operation, good technical support, and reasonable price. The following figure is the working interface of ICCAVR. AVRStudio Integrated Development Environment AVRStudio is an integrated development environment that integrates project management, program assembly, program debugging, program download, JTAG simulation, and so on. However, AVRStudio does not support the C programming language. Therefore, when we develop an AVR microcontroller with the C programming language, we should first compile the C programming language with ICCAVR, then open the compiled code file with AVRStudio to debug the program. The following figure is the workspace of SVRAStudio. PonyProg2000 software  It is mainly used for AVR MCU and PIC MCU program download, can be used in Windows95/98/ME/NT/20001XP operating systems. The following figure is the working interface of PonyProg2000. Attention Write with PORTx, read with PINx During the experiment, try not to connect the pin directly to the GND/VCC. When it is not set properly, the I/O port will output/fill the high current of 80mA (Vcc=5V), resulting in device damage. As Input 1.The suspension (high resistance state) will be susceptible to interference if the internal pull-up resistor is usually allowed(generally, it seems that 51 has a strong anti-interference ability because 51 always has internal resistance to pull up). 2.Try not to let input suspended or analog input level close to VCC/2, because it will consume too much current, especially in low power applications of CMOS circuits. 3.The pin level provided by the reading software usually requires a clock cycle interval between the assignment instruction “out” and the read instruction “in”, such as the nop order. 4.The input of the functional module (interrupt, timer) can be triggered by a low level, also it can be the rising edge trigger or the falling edge trigger. 5.For high-resistance analog signal input, remember not to allow internal pull-up resistor to affect accuracy, such as ADC digital-analog converter input, analog comparator input, and so on. As Output Taking the necessary current limiting measures, for example, drive the LED to serialize the current-limiting resistor. Reset The internal pull-up resistor will be disabled when to reset. If strict level control is required in an application, such as motor control, it is necessary to use an external resistor to fix the level. Dormant As output, it is still in the same state Input is generally invalid, but the input function is valid if the second function is interrupted. For example, the wake-up function of an external interrupt FAQ 1. What is meant by AVR microcontroller? AVR is a family of microcontrollers developed since 1996 by Atmel, acquired by Microchip Technology in 2016. These are modified Harvard architecture 8-bit RISC single-chip microcontrollers. AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to one-time programmable ROM, EPROM, or EEPROM used by other microcontrollers at the time. 2. How does AVR microcontroller work? AVR is an 8-bit microcontroller belonging to the family of Reduced Instruction Set Computer (RISC). In RISC architecture the instruction set of the computer are not only fewer in number but also simpler and faster in operation. ... The input/output registers available are of 8-bits. 3. What does AVR stand for in electronics? An automatic voltage regulator (AVR) is an electronic device that maintains a constant voltage level to electrical equipment on the same load. 4. What are the types of AVR? In general, there are two types of an Automatic Voltage Regulator. One is the Relay Type and the other is the Servo Motor type. A Relay type AVR makes use of electronic circuitry like relays and semi-conductors to regulate the voltage. 5. Is Arduino AVR or ARM? Arduino uses AVR- or ARM-based microcontrollers, depending on board. PIC is the oldest of the lot. There's no such thing as an “Arduino microcontroller”. 6. What is full form of AVR? The Full form of AVR is Aortic Valve Replacement. An AVR is a type of open heart surgery used to treat problems with the heart's aortic valve. 7. What happens if AVR fails? When AVR fails a protection called Field Failure protection will come into picture and trip the generator. ... If Failure of field is associated with under voltage which might happen due to severe fault near the generator and AVR might trip not able to maintain the voltage, the generator is tripped instantaneously. 8. What is AVR and ARM? ARM is a microprocessor or CPU architecture while AVR is a microcontroller. ARM can be used similar to a microcontroller when combined with ROM, RAM and other peripherals to a single chip like LPC2148. ... Microcontroller has build in RAM, ROM and other peripherals in a single chip. While microprocessor has only the CPU. 9. What are the applications of AVR and ARM? AVR and ARM comes under the family of micro-controller. But ARM can be used as both Microcontroller or as Microprocessor. ARM micro-controller and AVR micro-controller differs from each other in terms of different architecture and different sets of instruction, speed, cast, Memory, Power Consumption, Bus Width etc. 10. What is AVR microcontroller architecture? AVR is a 8-bit RISC architecture (Reduced Instruction Set Computing) microcontroller in market since 1996 which is having on-chip programmable flash memory, SRAM, IO data space & EEPROM. AVR is the first MCU in market which has on-chip flash storage. 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What is a capacitor? Capacitor, a electronic component to hold charges, represented by the letter C. It composes of two metal electrodes between a layer of insulating dielectric. When a voltage is applied between the two metal electrodes, the charge is stored on the electrode, so the capacitor is an energy storage electrical part. Any of two conductors that are insulated and close to each other form a capacitor. In addition, the parallel plate capacitor consists of the electrode plate and the dielectric of the capacitor.  Capacitor is one of the widely used electronic components in electronic equipment. It is widely used in stopping DC and alternating AC, coupling, bypass, filtering, tuning loop, energy conversion, control and so on. Capacitor is different from capacitance. The capacitance is the basic physical quantity, the symbol C, the unit is F (Farah).   A video introducing basic knowledge of capacitors Catalog   I. Capacitor characteristics II. Functions of capacitor in electrical circuits III. How to use capacitors? IV. Capacitor types V. Capacitor volume VI. Charge and discharge of a capacitor VII. Matters needing attention when using capacitors VIII. Common fault of capacitor and treatment method FAQ   I. Capacitor characteristics  - It has the ability of charge and discharge, preventing DC current from passing through, allowing AC current to pass through.  - During the charge and discharge process, the charge on the bipolar plate accumulates, that is, the voltage is set up, therefore, the voltage on the capacitor will not change abruptly. Charging: two plates with the same amount of dissimilar charge, each plate with the absolute value of the charge is called capacitor volume. Discharging: positive and negative charges at both ends of capacitors are neutralized through conductors. During discharge, there is a transient current on the wire. Capacitor charge  - The capacitive reactance of capacitors is inversely proportional to frequency and capacity. When analyzing the capacitance, the frequency and capacity of the contacting signal must be analyzed. Formula of parallel plate capacitor The dielectric constant of vacuum εr=1, k is a constant of hydrostatic power, s is the positive area of two plates, and d is the distance between two plates. Explanation: the electric field in the parallel plate capacitor is uniform electric field. II. Functions of capacitor in electrical circuits In DC circuits, the effect of a capacitor is equivalent to a open circuit. Capacitors are one of the most commonly used electronic components to store charge. Capacitors are used in electronic circuits as low-pass, high-pass and band filters. A filter is a circuit that allows current and voltage of a specified frequency and waveform to pass through. A capacitor's reactance is inversely proportional to frequency. By controlling or changing the reactance, you can control the frequency allowed through the circuit. Capacitors also play a significant role in high-speed switching logic circuits. Such circuits' voltage level, which should be steady, can change with current fluctuation, thereby introducing noise or error signals. Decoupling capacitors are built into circuits to stabilize the current, minimizing noise signals. The effect of capacitor links with the structure of itself. The simplest capacitors are made up of polar plates at both ends and insulating dielectric (including air) at the middle. After electrification, the plate is charged, forming a voltage (potential difference), but the entire capacitor is non-conductive because of the intermediate insulation. However, the condition is that the critical voltage (breakdown voltage) of the capacitor is not exceeded. We know that any substance is relatively insulated, and when the voltage at both ends of the material increases to a certain extent, the material can conduct electricity. We call this voltage a breakdown voltage. When the capacitor is broken down, it is not an insulator. However, in AC circuits, the direction of the current changes with time, that is, this change has functional relation. The charging and discharging process of capacitors is time-dependent, and at this time, a varying electric field is formed between the plates, and this electric field is a function of the change with time. In fact, the current passes between capacitors in the form of an electric field. III. How to use capacitors? As a relatively common electronic component, capacitors have a wide range of uses. The following content gives you a brief introduction to the 9 most common scenarios where capacitors are used: Stopping DC, bypass (decoupling), coupling, filtering, temperature compensation, timing, tuning, rectifier, and energy storage. 1.Stopping DC: the function is to prevent the passage of DC and allow the AC to pass through. DC blocking capacitor 2. Bypass (decoupling): it provides a low impedance path for some parallel components in AC circuits.       Signal input and output   3. Coupling: as a connection between two circuits, AC signals are allowed to pass and transmitted to the next stage of the circuit. Coupling capacitor circuit model Capacitor as coupling component The purpose of using capacitor as coupling part is to transmit the front stage signal to the next stage, and to separate the influence of the DC of the former stage on the latter stage, so that the circuit is simple to debug and its performance is stable. The amplification of AC signal without capacitor will not changed, but the work points at all levels need to be redesigned. Because of the influence of the front and back stages, to debug at working points is very difficult and can hardly be realized at multistage. 4. Filtering: this is very important for the circuit, the capacitor behind the CPU is having this function basically. Impedance formula(filtering circuit) That is, the larger the frequency f, the smaller the impedance Z of the capacitance. At low frequency, the capacitance C can pass smoothly because of the large impedance Z, and at high frequency, the capacitance C is very small because of the impedance Z, which is equivalent to shorting the high frequency noise to the GND. 5. Temperature compensation: it improves the stability of the circuit by compensating for the influence of other components on the temperature adaptability.   Temperature compensation Analysis: because the capacity of the timing capacitor determines the oscillation frequency of the horizontal oscillator, the capacity of the timing capacitor must very stable and does not change with the humidity in the environment. Therefore, the capacitors with positive and negative temperature coefficients are used for temperature complementation. When the operating temperature increases, the capacity of Cl is increasing, while the capacity of C2 is decreasing, and the total capacity of two capacitors is the sum of the two capacitors after parallel connection. Because one capacity is increasing and the other is decreasing, the total capacity is basically stable. Similarly, when the temperature decreases, the capacity of one capacitor decreases while the other increases, and the total capacity is basically unchanged, which stabilizes the oscillation frequency and realizes the purpose of temperature compensation. 6. Timing: the use of capacitors in conjunction with resistors to determine the time constant of the circuit. Capacitor and resistor(timing) Inputting signal from low to high, after buffer 1 then input RC circuit. The characteristics of capacitor charging make the B point signal not change immediately with the input signal, but there is a gradual process of increasing. When it becomes larger to a certain extent, the buffer 2 flips over, resulting in a delay jump from low to high at the output end. 7. Tuning: having systematic tuning to circuits which related to frequency, such as cell phones, radios, and televisions. System tune Because the resonant frequency of the oscillation circuit is a functional relation of lc. It is fond that the ratio of maximum to minimum resonant frequency varies with the square root of capacitance ratio. Here the capacitance ratio refers to the ratio of the capacitance at the minimum reverse bias voltage to the capacitance at the maximum reverse bias voltage. Therefore, the tuning characteristic curve (bias voltage and resonant frequency) is basically a parabola. 8. Rectifier: switch on or off a semi-closed conductor component at a predetermined time. Rectification Filtering wave form 9. Energy storage: storage of electrical energy for release when necessary. For example, camera flashlights, heating devices, etc. (some capacitors now store energy at levels close to lithium batteries; a capacitor can store electricity as one-day power for a mobile phone.   IV. Capacitor types According to the analysis and statistics, capacitors are divided into the following 10 categories: 1. According to the structure: solid capacitor, variable capacitor and fine-tuned capacitor. 2. Classified by electrolytes: organic dielectric capacitor, inorganic dielectric capacitor, electrolytic capacitor, electrothermal capacitor and air-spaced capacitor. 3.According to the usage: high-frequency bypass  capacitor, low-frequency bypass  capacitor, filtering capacitor, tuning capacitor, high-frequency coupling capacitor, low-frequency coupling capacitor, small capacitor. 4. According to the different materials: ceramic capacitor, polyester capacitor, electrolytic capacitor, tantalum capacitor, advanced polypropylene capacitor etc. 5. High frequency bypass: ceramic capacitor, mica capacitor, glass film capacitor, polyester capacitor, glass-glazed capacitor. 6. Low frequency bypass: paper capacitor, ceramic capacitor, aluminum electrolytic capacitor, polyester capacitor. 7. Filter: aluminum electrolytic capacitor, paper capacitor, composite paper capacitor, liquid tantalum capacitor. 8. Tuning: ceramic capacitors, mica capacitors, glass film capacitors, polystyrene capacitors. 9. Low coupling: paper capacitor, ceramic capacitor, aluminum electrolytic capacitor, polyester capacitor, solid tantalum capacitor. 10. Small capacitors: metallized paper capacitor, ceramic capacitor, aluminum electrolytic capacitor, polystyrene capacitor, solid tantalum capacitor, glass-glazed capacitor, metallized polyester capacitor, polypropylene capacitor, mica capacitor. V. Capacitor volume Since capacitors are a container for storing charges, there is a problem of capacity. In order to measure the capacity of capacitors to store charges, the capacity is determined. A capacitor must store a charge under the action of an applied voltage. The amount of charge stored in different capacitors under voltage may also different. According to the international standard, when the capacitor is subjected to a 1V DC voltage, the value is the charge that can store in the the capacitor (that is, the electric quantity per unit voltage), which is expressed by the letter C. The basic unit of capacitance is the Farah (F). At 1V DC voltage, if the capacitor stores the charge is 1 Coulomb, the capacitance is set at 1 farah, and Farah is represented by the symbol F, 1 F=1 Q/ V. In practical application, the capacitance of capacitors is often much smaller than that of 1F, and is often used in smaller units, such as mF, μF, nF, pF, etc. The relationship between them is as follows:   1F=1000mF1mF=1000μF1μF=1000nF1nF=1000pF1F=1000000μF1μF=1000000pF VI. Charge and discharge of a capacitor When the capacitor is connected to the power supply, under the action of the electric field force, the free electron connected with the positive electrode of the capacitor moves through the power supply to the plate connected to the negative electrode of the power supply. The positive electrode is positively charged because of the loss of the negative charge; the negative electrode is negatively charged because of gaining negative charge. The positive and negative plates have the same charge size and the opposite sign, so the charge moves in a fixed direction to form a current. Due to the repulsive effect of the same charge, the initial current is maximum, and then decreases gradually. During the process of charge movement, the charge stored on the electrode plate of the capacitor increases continuously. When the voltage Uc between two poles of capacitor is equal to the power-supply voltage U, the charge stop moving. The current I=0, switch closed, through the wire connection, the capacitor plate charge neutralized. When K is closed, on the one hand, the positive charge of the capacitor C can be neutralized on the negative electrode; on the other hand, the negative charge of the negative electrode can also be moved to the positive electrode. The charge gradually decreases, the apparent current decreases and the voltage decreases to zero. VII. Matters needing attention when using capacitors Because the two poles of the capacitor have the residual charge, it is necessary to release the charge at first, otherwise the electric shock will occur easily. When dealing with the faulty capacitor, the circuit breaker and the upper and lower disconnector of the capacitor set should be opened first, and if the fuse protection is adopted, the fuse tube should be removed first. At this time, although the capacitor set has discharged  itself, there will still be part of the residual charge, therefore, it is necessary to carry out manual discharge. When discharging, the grounding end of the ground wire and the grounding grid should be fixed first, then the capacitor should be discharged with the grounding rod several times until there is no spark and discharge sound, and finally the ground wire is fixed again. Meanwhile, it should also be noted that if the capacitor has internal breakage, fuse failure or poor lead contact, there may be residual charges between the two poles, which will not be released during automatic discharge or manual discharge. Therefore, the operation or maintenance personnel should wear insulating gloves before contacting the faulty capacitor, and use a short line to connect the two poles of the fault capacitor to make it discharge. In addition, the capacitor with series connection should be discharged separately. VIII. Common fault of capacitor and treatment method (1) When the capacitor explodes, the power should cut off immediately and extinguish the fire with sand and dry-firefighter. (2) When the capacitor fuses, it shall report to the dispatch and open the circuit breaker of the capacitor after obtaining the consent. When the power supply is cut off to discharge it, external checks are carried out, such as whether there are flashover marks on the outside of the casing, whether the casing is deformed, the oil leakage and the short circuit of the earthing device, etc., and the insulation resistance between the poles and the ground is measured. Check whether the capacitor set connection is complete, firm, lacking of phase phenomenon. If not found fault phenomenon, it can be replaced after the investment. If the insurance still melts after power transmission, the faulty capacitor should be withdrawn and the rest should be power on. If the circuit breaker tripped at the same time as the fuse, at this time, don’t connect power supply. After the above inspection has been completed, the insurance must be replaced. (3) The circuit breaker of the capacitor tripped and the shunt safety was not broken, the capacitor should be discharged for three minutes before checking the power cable of the circuit breaker current inductor and the outside of the capacitor. If no anomaly is found, it may be due to external fault bus voltage fluctuations. After inspection, it may be put on trial; if not, a comprehensive test of the protection should be carried out. Through the above inspection, the test, if still can not find the reason, it is necessary to act according to the system, the capacitor is gradually tested. No trial test shall be made until the cause has been found.   FAQ   1. What is a capacitor used for? A capacitor (originally known as a condenser) is a passive two-terminal electrical component used to store energy electrostatically in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e., insulator).   2. What is capacitor and how it works? In a way, a capacitor is a little like a battery. Although they work in completely different ways, capacitors and batteries both store electrical energy. ... Inside the capacitor, the terminals connect to two metal plates separated by a non-conducting substance, or dielectric.   3. When should you use a capacitor? Power Supply Smoothing. This is the easiest and very widely used application of a capacitor. ... Timing. If you supply power to a capacitor through a resistor, it will take time to charge. ... Filtering. If you pass DC through a capacitor, it will charge and then block any further current from flowing.   4. What is capacitor and its types? The most common kinds of capacitors are: Ceramic capacitors have a ceramic dielectric. Film and paper capacitors are named for their dielectrics. Aluminum, tantalum and niobium electrolytic capacitors are named after the material used as the anode and the construction of the cathode (electrolyte).   5. Are capacitors AC or DC? When we connect a charged capacitor across a small load, it starts to supply the voltage (Stored energy) to that load until the capacitor fully discharges. Capacitor comes in different shapes and their value is measured in farad (F). Capacitors are used in both AC and DC systems (We will discuss it below).   6. What is the principle of capacitor? A capacitor is a device that is used to store charges in an electrical circuit. A capacitor works on the principle that the capacitance of a conductor increases appreciably when an earthed conductor is brought near it. Hence, a capacitor has two plates separated by a distance having equal and opposite charges.   7. Are capacitors dangerous? Capacitors may store hazardous energy even after the equipment has been de-energized, and may build up a dangerous residual charge without an external source. "Grounding" capacitors in series, for example, may transfer (rather than discharge) the stored energy.   8. What type of capacitor should I use? The general rule is always use a capacitor with a higher working voltage than the circuit it is used in. This is of particular importance in power supply circuits with high value electrolytic capacitors. The working voltage should always exceed the peak working voltage of the circuit by a minimum of 20%.   9. What is capacitor and its applications? Capacitor is a basic storage device to store electrical charges and release it as it is required by the circuit. Capacitors are widely used in electronic circuits to perform variety of tasks, such as smoothing, filtering, bypassing etc…. One type of capacitor may not be suitable for all applications.   10. Do capacitors change AC to DC? No, capacitor cannot convert AC to DC. Capacitor can add DC to AC so that zero reference of AC signal can be changed, in other words capacitor works as level shifter.   11. Can Capacitors store AC? Capacitors do not store AC voltage - it stores voltage. It's rated to handle 450 VAC; that means it can withstand an AC voltage being applied to it. In other words, the capacitor is non-polar (it has no positive or negative lead). Polar (or polarized) capacitors are best known as "Electrolytic" capacitors.   12. What is the difference between a capacitor and a battery? A battery is an electronic device that converts chemical energy into electrical energy to provide a static electrical charge for power. Whereas a capacitor is an electronic component that stores electrostatic energy in an electric field.   13. How much current can a capacitor handle? A 3.5V charger will charge the capacitor up to 3.5V only. You need a higher voltage DC source to charge the capacitor to higher potential. Remember, in your case, 100V is the maximum which capacitor can handle.   14. What happens when a capacitor fails? During a failure, half of the capacitor could fail open, which would result in overall capacitance being lost. Or half of the capacitor could fail short, which would result in the overall capacitance being halved.   15. Does type of capacitor matter? Yes, the type of capacitor can matter. Different types of capacitor have different properties. Some of the properties that vary between capacitor types: a. Polarised vs unpolarised b. Max voltage c. Equivalent Series Resistance (ESR) d. Lifetime (electrolytics are particularly bad in this case) e. Physical size (e.g. a 100,000 uF ceramic capacitor would be HUGE!) f. Tolerance of capacitance (again, electrolytics are bad here, often being +/- 20%