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IntroductionResistors are usually connected in a circuit in various ways, and the two most basic ways are series and parallel. This article will mainly introduce these two connection methods, including their definitions, formulas, circuit diagrams, examples and identification methods. In addition, the article also introduces Ohm's law and Kirchhoff's law, which are very important in understanding the series and parallel connections of resistors.You may need these two calculators in reading this arrticle:① Ohm's Law Calculator② Parallel and Series Resistance CalculatorThe following video explains the basics of resistors in series and parallel, which can promote your understanding of this article. But it does not matter so much if you skip this video since the article explains in detail and is comprehensive.Resistors in series and parallel - deriving the formulaCatalogIntroductionCatalogI Series Connection of ResistorsII Parallel Connection of ResistorsIII Resistor Combination(Mixed Resistor Circuit)IV Ohm's Law  4.1 What is Ohm's Law?  4.2 What is Closed Circuit Ohm's Law?  4.3 The Key Points of Studying Ohm's LawV Kirchhoff's Law  5.1 Concepts  5.2 Kirchhoff's First Law (Nodal Current Law)  5.3 Kirchhoff's Second Law (Law of Loop Voltage)  5.4 Application Note of Kirchhoff's LawVI Series and Parallel Circuit Identification MethodsVII QuizⅧ FAQI Series Connection of Resistors(1) Circuit characteristicsFigure1. Resistors in seriesThe figure shows the series connection of n resistors, and the voltage and current reference directions are related. The circuit characteristics are derived from Kirchhoff’s law:(A) The resistors are connected in sequence. According to KCL, the current flowing through the resistors is the same;(B) According to KVL, the total voltage of the circuit is equal to the sum of the voltages of the series resistors, namely:(2) Equivalent resistanceFigure2. Equivalent resistance circuitSubstituting Ohm's law into the voltage expression, we get:The above formula illustrates that the series circuit of multiple resistors in Figure (a) and the circuit of single resistor in Figure (b) have the same VCR, which is equivalent to each other.The equivalent resistance is:In conclusion:The resistors are connected in series, and the equivalent resistance is equal to the sum of the sub-resistances;The equivalent resistance is greater than any one of the series resistance.The partial pressure of series resistanceIf the total voltage across the series resistor is known, what is the divided voltage on each resistor? From figure (a) and figure (b) we know:MeetIn conclusion:Resistors are connected in series, and the voltage on each sub-resistor is proportional to the resistance value. The higher the resistance value, the higher the voltage. Therefore, the series circuit can be used as a voltage divider circuit.Example 1: Calculate the voltage across the two series resistors as shown in the figure.Figure3. Circuit of Example1Solution: From the partial pressure formula of series resistance:(Note the direction of U2)(3) PowerThe power of each resistor is:SoTotal power:Draw conclusions from the above formulas:When resistors are connected in series, the power consumed by each resistor is proportional to the size of the resistor, that is, the larger the resistance, the larger the power consumed;The power consumed by the equivalent resistance is equal to the sum of the power consumed by each series resistor.II Parallel Connection of Resistors(1) Circuit characteristicsFigure4. Parallel circuit characteristics The figure shows the parallel connection of n resistors, and the voltage and current reference directions are related. The circuit characteristics are derived from Kirchhoff's law:(a) The two ends of each resistor are connected together. According to KVL, the two ends of each resistor are at the same voltage;(b) According to KCL, the total current of the circuit is equal to the sum of the currents flowing through the parallel resistors, namely:(2) Equivalent resistanceFigure5. Equivalent resistance in parallel connectionSubstituting Ohm's law into the current expression, we get:G =1/R is the conductanceThe above formula illustrates that the parallel circuit of multiple resistors in Figure (a) and the circuit of single resistor in Figure (b) have the same VCR, which is equivalent to each other.The equivalent conductance is:Therefore,Namely,The most commonly used formula to find the equivalent resistance when two resistors are connected in parallel:In conclusion:The resistors are connected in parallel, and the equivalent conductance is equal to the sum of the conductances and greater than the partial conductance;The reciprocal of the equivalent resistance is equal to the sum of the reciprocals of the sub-resistances, and the equivalent resistance is less than any parallel sub-resistance.Current distribution of parallel resistanceIf the total current of the parallel resistance circuit is known, find the current on each sub-resistance and call it a shunt. From figure (a) and figure (b) we know:Namely,MeetFor two resistors in parallel, there are:Conclusion: When the resistors are connected in parallel, the current on each sub-resistor is inversely proportional to the resistance value, and the current divided by the larger resistance value is smaller. Therefore, the parallel resistor circuit can be used as a shunt circuit.(3) PowerThe power of each resistor is:SoTotal power:Draw conclusions from the above formulas:When resistors are connected in parallel, the power consumed by each resistor is inversely proportional to the size of the resistor, that is, the larger the resistance, the smaller the power consumed;The power consumed by the equivalent resistor is equal to the sum of the power consumed by each parallel connected resistor.consumed by each series resistor.III Resistor Combination(Mixed Resistor Circuit)A circuit with resistors connected in series and connected in parallel is called a resistor combination or mixed resistor circuit. The part where the resistors are connected in series has the characteristics of a resistor series circuit, and the part where the resistors are connected in parallel has the characteristics of a resistor parallel circuit.Example 2: The circuit is shown in the figure, please calculate the voltage and current of each branch.Figure6. Example circuit 2Solution: This is a resistor series and parallel circuit. First find the equivalent resistance Reg = 11W, and the current and voltage of each branch are:The general steps for solving series and parallel circuits can be obtained from the above examples:⚫ Find the equivalent resistance or equivalent conductance;⚫ Apply Ohm's law to find the total voltage or total current;⚫ Apply Ohm's law or voltage division and shunt formula to find the current and voltage on each resistor.Therefore, the key issue in analyzing series-parallel circuits is to distinguish the relationship between series and parallel circuits.To determine the series-parallel relationship of the circuit, the following 4 points should be mastered:⚫ Look at the structural characteristics of the circuit. If two resistors are connected end-to-end, they are connected in series;⚫ Look at the relationship between voltage and current. If the current flowing through the two resistors is the same current, it is connected in series; if the two electrical groups bear the same voltage, it is connected in parallel.⚫ Equivalent to deformation of the circuit. For example, the left branch can be twisted to the right, the upper branch can be turned down, the curved branch can be straightened, etc.; the short circuit in the circuit can be compressed and extended at will; the multi-point grounding can be connected by a short circuit . Generally, if it is really a problem with a resistor series circuit, it can be distinguished.⚫ Find the equipotential point. For circuits with symmetrical characteristics, if two points can be judged to be equipotential points, according to the concept of circuit equivalence, one is to use short wires to connect the equipotential points; the other is to break the branch that connects the equipotential points. Open (because there is no current in the branch), thus obtain the series-parallel relationship of the resistance.IV Ohm's Law4.1 What is Ohm's Law?(1) The content of Ohm's lawWhen there is a potential difference between the two ends of the conductor, an electric field appears inside the conductor, and the charge moves in a directional motion under the force of the electric field to generate current. German physicist Ohm summed up Ohm's law in 1826 through a large number of experiments: Under steady conditions, the intensity of the current passing through a section of conductor is proportional to the voltage across the conductor.(2) Mathematical expression of Ohm's law Note: The unit of the physical quantity in the formula: the unit of I is ampere (A), the unit of U is volt (V), and the unit of R is ohm (Ω).The proportional coefficient R in the formula is determined by the properties of the conductor and is called the resistance of the conductor. Unit: Ohm (Ω). The reciprocal of resistance is called conductance and is represented by G, that isUnit: Siemens (S).(3) Understanding and explanation of Ohm's law● Applicable conditions of Ohm's law: applicable to pure resistance circuits (that is, when working with electrical appliances, the consumed electrical energy is completely converted into internal energy.)● I, U and R in the formula must correspond to the same conductor or the same circuit. If it is in different time, different conductor or different section of circuit, I, U, and R can not be mixed, therefore, the three physical quantities should be marked with angles in order to distinguish under normal circumstances.● For the same conductor (that is, R does not change), I and U are proportional; for the same power source (that is, U does not change), I and R are inversely proportional.● R=ρL/S is the definition of resistance, which means that the resistance of a conductor is determined by the material, length and cross-sectional area of ​​the conductor itself. In addition, resistance is also related to factors such as temperature.● The formula transformed from Ohm's law is a measure of resistance. It indicates that the resistance of a conductor can be given by U/I, that is, the ratio of R to U and I is related, but the magnitude of R itself is related to the applied voltage U and the passing current Factors such as the size of I are irrelevant.● Knowing any two quantities among I, U and R, you can find another quantity.● Issues that need special attention and re-emphasis: I, U and R in the formula must be in the same circuit; when using the formula to calculate, the unit of each physical quantity must be unified.The above explanations are all part of Ohm’s law, which only applies to pure resistance circuits.(4) Pure resistance circuitA pure resistance circuit is a circuit with only resistance elements in addition to the power supply, or inductance and capacitance elements, but their influence on the circuit is negligible. The voltage and current have the same frequency and phase.The resistance converts all the energy obtained from the power supply into internal energy. This kind of circuit is called a pure resistance circuit. Here is a brief explanation from the energy point of view.Basically, as long as there is no conversion of electric energy other than internal energy, this circuit is a pure resistance circuit.4.2 What is Closed Circuit Ohm's Law?In an AC circuit, Ohm's law also holds, but the resistance R should be changed to impedance Z, that is, I = U/Z. If the circuit is closed and contains a power supply, it is called a full circuit, as shown in the figure below. The dotted line in the figure is the power supply, which is called an internal circuit. The circuit outside the power supply is called an external circuit. Since the power supply has internal resistance, the current not only has a voltage drop when passing through an external circuit, but also has an internal voltage drop when passing through an internal circuit. In the whole circuit, the current intensity is proportional to the electromotive force E of the power supply, and inversely proportional to the resistance (R+r) of the whole circuit (including the inner circuit and the outer circuit). This is the Ohm's law of the whole circuit, expressed by the formula:Where I- the current in the circuit, A; E- the electromotive force of the power supply, V; R- the resistance of the external circuit, Ω; r- the resistance of the internal circuit, Ω.From the above formula, in the circuit shown in the figure below, E=IR+Ir=Uouter+Uinner.Figure7. The simplest closed circuitIn the formula, U external = IR-external circuit voltage; U internal = Ir-internal circuit voltage.It should be noted that, since the internal resistance of the power supply itself and the internal resistance of the connecting wires are generally not large, the calculation results that are ignored in the calculation are basically correct. But sometimes it is necessary to calculate the internal voltage drop of the power supply, and to accurately calculate the current of the whole circuit, it is necessary to use the whole circuit Ohm's law. For example, in the figure below, if E=10V, r=0.1Ω, R=1kΩ, then:Figure8. An application example of Ohm's law of closed circuit① When S is connected to the 1 position, the circuit is in the open state,Ammeter readingThe reading of the voltmeter is U=IR=0.01×1000=10 (V), or U=E-Ir=10-0.01×0.1≈10 (V).②When S is connected to the 2 position, the circuit is in an open state, so the reading of the ammeter is 0; the reading of the voltmeter is U=E=10(V).③When S is connected to the 3 position, the circuit is in a short-circuit state, the reading of the ammeter is I=E/r=10/0.1=100(A)A; the reading of the voltmeter U=0(V).4.3 The Key Points of Studying Ohm's LawOhm's law is an important basic law in electricity. It is a law that is summarized and summarized through experiments. To master this law, we must pay attention to the following points:(1) Ohm's law applies to the entire circuit or a part of the circuit from the positive pole to the negative pole of the power supply, and it is a pure resistance circuit.(2) The current I "passing through" in Ohm's law, the voltage U at "both ends" and the resistance R of the "conductor" are all corresponding physical quantities on the same conductor or the same circuit. The above relationship does not exist between the current, voltage, and resistance of different conductors. Therefore, when using the formula I=U/R, the current, voltage, and resistance of the same conductor or the same circuit must be substituted into the calculation, and the three correspond one to one.(3) There is simultaneity among the three physical quantities in Ohm’s law. Even on the same part of the circuit, the closing or opening of the switch and the movement of the sliding position of the sliding varistor will cause the change of the circuit, which will lead to the current in the circuit. , Voltage, resistance changes, so the three quantities in the formula I=U/R are the same time value.(4) The difference between I=U/R and R=U/I:Ohm's law expression I=U/R means that the current in the conductor is related to the voltage across the conductor and the resistance in the conductor. When the resistance R is constant, the current I in the conductor is proportional to the voltage U across the conductor; when the voltage U across the conductor is constant, the current I in the conductor is inversely proportional to the resistance R of the conductor.R=U/I is derived from Ohm’s law expression. It means that the resistance value of a certain section of conductor is equal to the ratio of the voltage across the section of the conductor to the current passing through it. This ratio R is the property of the conductor itself and cannot be understood as R is directly proportional to U and inversely proportional to I. This is also the difference between physics and mathematics.(5) Ohm's law reflects the causal relationship between current intensity and voltage, and the restrictive relationship between current intensity and resistance under certain conditions. That is, when the resistance is constant, the current intensity is proportional to the voltage across the conductor; when the voltage is constant, the current intensity is inversely proportional to the resistance of the conductor. When establishing a proportional relationship, we must pay attention to its conditions. Ohm's law states that the current intensity through a conductor is determined by two factors, the voltage across the conductor and the resistance of the conductor.V Kirchhoff's LawKirchhoff's law includes the first law and the second law. They are the basic laws that are indispensable for the analysis and calculation of complex circuits.5.1 Concepts • BranchA two-terminal element connected in a circuit is a branch. Usually a certain current flows through the branch. (This definition is not universal. For example, if two components are connected in series and then connected in a circuit, it can only be regarded as a branch.)• NodeThe connection point between the branch and the branch is called a node. Usually the current diverges at the junction.• Loop loopA closed path formed by branches is called a loop.Figure9. 6 elements, 6 branches, 4 nodes, 3 independent circuits5.2 Kirchhoff's First Law (Nodal Current Law)The textual expression of KCL: For any node, the algebraic sum of the current flowing into (or out of) the node is equal to zero.Its mathematical expression:The regulation of current positive and negative: Generally, the current flowing into the node is positive, and the current flowing out of the node is negative.The physical meaning of KCL: conservation of chargeNote: KCL is not only applicable to a node, but also to a part of the circuit, as shown in the shaded part of the above figure:i3＝i65.3 Kirchhoff's Second Law (Law of Loop Voltage)KVL’s literal expression: In any closed loop of the circuit, go around a circle in a certain direction, and the algebraic sum of the voltage of each segment is zero.That is: or. When applying the law of loop voltage, the electromotive force is often written on the left side of the equation, and the voltage is written on the right side of the equation.The method for determining the sign of each electromotive force and voltage in the second expression is as follows:① First select the current direction of each branch.② Any choice of the detour direction along the loop (clockwise or counterclockwise).③ If the direction of the current flowing through the resistor is the same as the detour direction, the voltage drop on the resistor is positive, otherwise, it is negative.④ If the direction of the electromotive force is the same as the direction of the orbit, the electromotive force is positive, otherwise, it is negative.The physical meaning of KVL: energy conservation.5.4 Application Note of Kirchhoff's Law• Kirchhoff’s law is a general law that the circuit should satisfy, and has nothing to do with the specific properties of the components;• Kirchhoff’s law applies to any lumped circuit, that is, nonlinear, time-varying circuits, etc.;• Application steps:A. Divide the branch roads and number them;B. Specify the branch current and voltage reference direction, and generally need to be associated;C. Select the appropriate node according to the meaning of the question, and apply KCL;D. Or choose the appropriate circuit according to the meaning of the question, apply KVL, and pay attention to independence.Example: Use KVL to derive the relationship between the total resistance and the sub-resistance and the voltage division formula in the series resistance circuit.Apply KVL according to the current and voltage reference direction and the detour direction of the loop calibrated in the figure:-u+u1+u2+…+un = 0 or u=u1+u2+…+un Because the voltage and current of each resistor obey Ohm's law: uk=iRk, there are:u = i × R1 + i× R2 +...... +i× Rn = i× ( R1+R2+…+Rn)= i Re among them: Re=R1+R2+…+Rn, which is the total resistance or equivalent resistance.uk = iRk=( u/Re ) Rk, which is the voltage division formula of the series circuitVI Series and Parallel Circuit Identification MethodsMethod 1: Current flow method(1) Starting from the positive pole of the power supply, use arrows to mark the path of the current along the connected wires, and finally return to the negative pole of the power supply;(2) Observe whether the current has a shunt and confluence point:If there is only one path for the current in the circuit, the components are connected in series (as shown in Figure a below);If there is a shunt point and a confluence point in the circuit, that is, the direction of the current is greater than one path, the components between the shunt point and the confluence point are connected in parallel (as shown in Figure b below)Figure10. Current flow methodMethod 2: Demolition methodRemove any electrical appliances:If the other electrical appliance cannot work, the two electrical appliances are connected in series (as shown in Figure a below)If the other consumer still works without being affected, the two consumers are connected in parallel (as shown in Figure b below)Figure11. Demolition methodMethod 3: Node MethodFor other non-intuitive non-series circuits, the situation is more complicated and needs to be judged according to several steps:The first step is to mark nodes. That is, use different letters (or symbols) to mark all nodes of the circuit. As shown in the following figure (a), the four points A, B, C, and D are all nodes in the circuit.The second step is to merge the nodes. According to the characteristics of the nodes, some of the nodes you have marked may be equivalent to the same node. The letters (or symbols) belonging to the same node must be changed to the same letter (or symbol), as shown in the circuit shown in Figure (a) Point A and point C are the same node, C should be changed to A, point B and point D should be the same node, D should be rewritten as B, that is to say, the circuit shown in Figure (a) essentially has two nodes A and B .Figure12. Node MethodThe third step is to determine the connection mode of the circuit. There are usually two ways to judge:Method one:Direct judgment: as shown in the figure (a) above, both ends of the resistors R1, R2 and R3 are independently connected to nodes A and B, so R1, R2 and R3 are connected in parallel.Method Two:Drawing judgment: that is, draw the intuitive equivalent circuit diagram of the original diagram. The specific drawing method of the intuitive equivalent circuit diagram of the circuit diagram in Figure (a) is: first determine the two points A and B on the paper, and then combine the original diagrams A and B. The components between the two points B are independently connected to the newly determined points A and B, as shown in the above figure (b), that is, the equivalent circuit diagram of figure (a) is figure (b).Warm reminder: The "node method" is generally used to identify irregular and more complex circuits, which has certain difficulties. There are many ways to identify series and parallel circuits, but you can choose the most suitable method according to your own understanding of the method when using it.VII QuizThe voltage dropped across the 300 ohm resistor isA. 6V B.9V C.2V D.30VAnswer: AⅧ FAQ1. What is the difference between two resistors connected in series, and two resistors connected in parallel?When resistors are in series then net resistance is the sum of individual resistances whereas in parallel it is the sum of the reciprocal of individual resistances.When a resistor is in series the current is the same through all resistors but the voltage is different. The sum of the voltage drop across each resistor is equal to the voltage across a resistor connected in series.When the resistor is in parallel the voltage across each resistor is the same while the current through each resistor is different.In series, the net resistance is higher (sum of each resistance) while in parallel net resistance is lower (net resistance is lower than smallest resistance connected in parallel). 2. Why are resistors connected in series and parallel?Connecting resistors in series increase their total resistance and the power they can handle by distributing the applied voltage. The current flow is the same for each resistor regardless of its resistance.Connecting resistors in parallel reduce their total resistance while at the same time increasing their power they can handle by sharing the current flow in the circuit. The voltage drop across each resistor is the same regardless of its resistance. 3. What is the difference between resistors in parallel and resistors in a series?For resistors in parallel, the voltage across them is the same while the current is the sum let take a case of two resistors connected in parallel the formula 1/Req=1/R1+1/R2 further simplify Req=R1*R2/(R1+R2)While for resistors in series their current is the same but the voltage is the sum and let still take the case of two resistors connected in series to obtain their equivalent Req= R1+R2. 4. How are resistors added in series and parallel?When resistors are connected one after each other this is called connecting in series. This is shown below. To calculate the total overall resistance of a number of resistors connected in this way you add up the individual resistances. This is done using the following formula: Rtotal = R1 + R2 +R3 and so on. 5. Why is resistance different in series and parallel?When resistors are connected in parallel, more current flows from the source than would flow for any of them individually, so the total resistance is lower. Each resistor in parallel has the same full voltage of the source applied to it, but divide the total current amongst them. 6. How do you calculate resistors in parallel?Parallel Resistor EquationIf the two resistances or impedances in parallel are equal and of the same value, then the total or equivalent resistance, RT is equal to half the value of one resistor. That is equal to R/2 and for three equal resistors in parallel, R/3, etc. 7. Why is resistance less in parallel?When resistors are connected in parallel, more current flows from the source than would flow for any of them individually, so the total resistance is lower. 8. How do you sum resistors in parallel?The sum of the currents through each path is equal to the total current that flows from the source. You can find total resistance in a Parallel circuit with the following formula: 1/Rt = 1/R1 + 1/R2 + 1/R3 +... If one of the parallel paths is broken, the current will continue to flow in all the other paths. 9. What happens when you add a resistor in series?When resistors are connected in series, the total voltage (or potential difference) across all the resistors is equal to the sum of the voltages across each resistor. ... In other words, the voltages around the circuit add up to the voltage of the supply. 10. What is the difference between series connection and parallel connection?A parallel circuit refers to a circuit with two or more two paths for the current to flow. ... In a series circuit, all the components are arranged in a single line. In a parallel circuit, all the components are arranged parallel to each other. 

IntroductionAn analog-to-digital converter, or A/D converter, or ADC for short, usually refers to an electronic device that converts an analog signal into a digital signal. Except for the most specialized analog-to-digital converters, all ADCs are implemented as integrated circuits (ICs). These are usually mixed-signal integrated circuit chips based on metal oxide semiconductor (MOS) that integrate analog and digital circuits.As we all know, ADC is mainly used to the digital acquisition of analog signals for for data processing purposes. The signals around us are generally continuously changing analog quantities, such as light, temperature, speed, pressure, sound, etc. However, most of us use digital equipment. If we want to use and process information easily, it is necessary to convert the analog quantity into a digital quantity and transmit it to the microcontroller or microprocessor. So how is ADC conversion realized? What kind of process is it? Reading the following note, you will definitely have a more comprehensive and systematic understanding of the analog-to-digital converter.What is ADC (Analog to Digital Converter)?CatalogIntroductionⅠ A/D Converter Basic1.1 Analog-to-Digital Converter Definition1.2 Analog to Digital Conversion Steps1.3 Why do We Need Analog-to-Digital Converter?Ⅱ Which A/D Converter is Better?Ⅲ What A/D Converter Includes?Ⅳ A/D Converter Applications and ICs4.1 Analog-to-Digital Converter Applications4.2 Analog-to-Digital Converter IC Modes ExplainedⅠ A/D Converter Basic1.1 Analog-to-Digital Converter DefinitionThe ADC converter is a system that converts analog signals into digital signals. It is a process of filtering, sample-and-hold, quantization and encoding. The analog signal passes band-limited filtering, sample-and-hold circuit, and becomes a ladder-shaped signal, and then passes through the encoder to make each level in the ladder-shaped signal become a binary code. Finally, the analog quantity is converted into a digital quantity and then transmitted to the CPU. That is to say, almost all energized data need ADC conversion. For example, electric energy metering of electric energy meters, weight measurement of electronic scales, temperature measurement of electronic thermometers, and communication fields.1.2 Analog to Digital Conversion StepsThe process of converting analog quantities into digital quantities is called analog-to-digital conversion, abbreviated as A/D, and the circuit that completes this function is called analog-to-digital converter, or ADC for short.Analog-to-Digital Conversion Steps Animation1) Sampling refers to replacing the original continuous signal in time with a sequence of signal samples at regular intervals, that is, discretizing the analog signal in time.2) Quantization uses a limited number of amplitude values to approximate the original continuously changing amplitude value, that is, changing the continuous amplitude of the analog signal into a limited number of discrete values with a certain interval.3) Encoding is based on a certain rule, the quantized value is represented by binary numbers, and then converted into a binary or multi-value digital signal stream. The digital signal obtained in this way can be transmitted through digital lines such as cables, microwave trunk lines, and satellite channels.The higher the signal frequency, the higher the operating frequency of the A/D circuit. The more digits, the more accurate the restoration accuracy of the signal. The I/O port of the MCU needs program cooperation to complete the A/D conversion. What’s more, the A/D chip can also be used alone to complete the analog-to-digital conversion.1.3 Why do We Need Analog-to-Digital Converter?Computer software, radio, and digital image acquisition all need the assistance of ADC converters, that is, the wave of human digitization has promoted the invention, development and continuous change of ADC converters. In short, the ADC converter plays an important role in human digitization.1) Many recording studios use 24-bit/96 kHz (or higher) pulse code modulation (PCM) or direct stream digital (DSD) recording formats, and then use ADC samples or decimates the signal for digital audio production on discs.2) Use ADC to store or transmit almost any analog signal in digital form. For example, TV tuner cards use fast video analog-to-digital converters. Digital storage oscilloscopes require very fast analog-to-digital converters, and ADCs are also crucial for software-defined radio and its new applications.3) Digital imaging systems usually use analog-to-digital converters to digitize pixels. Some radar systems usually use ADCs to convert signal strength into digital values for subsequent signal processing.4) Certain non-electronic or only partially electronic devices (such as rotary encoders) can also be regarded as analog-to-digital converters.Figure 1. Analog to Digital Conversion Example(Light Signal to Digital Signal) Ⅱ Which A/D Converter is Better?After years of development and continuous technological innovation, ADC converters have developed from Flash ADCs, Successive-Approximation ADCs, Counting/Slope Integration ADCs to sigma-delta (Σ-Δ) ADCs and Pipelined ADCs. They have their own advantages and disadvantages, and they can also meet different requirements.Successive-Approximation ADCs, Counting/Slope Integration ADCs and compression ADCs, etc. are mainly used in low-speed or medium-speed, medium-precision data acquisition and intelligent instruments. Hierarchical and pipelined ADCs are mainly used in high-speed signal processing, fast waveform storage and data recording, etc., such as video signal quantization and high-speed digital communication technology. ∑-△ ADC is mainly used in high-precision data acquisition, especially in electronic measurement fields such as digital sound systems, multimedia, seismic exploration instruments, sonar and so on. Here a brief description of the main ADC types is given below. Successive-Approximation ADCThe successive-approximation ADC is widely used. It includes a comparator, a digital-to-analog converter, a successive-approximation register (SAR) and a control logic unit. It is to continuously compare the sampling input signal with the known voltage. One clock cycle completes the 1-bit conversion, and the N-bit conversion requires N clock cycles. The conversion is completed and the output binary number is output. The resolution and sampling rate of this type ADC are contradictory: when the ADC resolution is low, the sampling rate is high, and if the resolution is to be improved, the sampling rate will be limited.Advantages: when the resolution is lower than 12 bits, the price is cheap, and the sampling rate can reach 1MSPS. Compared with other types, the power consumption is quite low.Disadvantages: In the case of higher than 14-bit resolution, the price is higher. The signal generated by the sensor needs to be conditioned before analog-to-digital conversion, including gain stage and filtering, so that the cost will increase significantly. Counting/Slope Integration ADCsCounting/Slope Integration ADC is also called dual-slope or multi-slope ADC, and its applications are also very wide. It is composed of an analog integrator with an input switch, a comparator and a counting unit. The input analog voltage is converted into a time interval proportional to its average value through two integrations. At the same time, a counter is used to count the clock pulses in this time interval, so as to realize the analog-to-digital conversion. Because the input end applies the integrator, it has a strong ability to suppress the interference of AC noise. For example, for high-frequency noise and fixed low-frequency (50Hz or 60Hz) interference suppression, it is suitable for use in noisy industrial environments. This type ADC is mainly used in low-speed, precision measurement and other fields, such as digital voltmeters.Advantages: High resolution, up to 22 bits; low power consumption and low cost.Disadvantages: The conversion rate is low, 100~300SPS at 12 bits. Parallel ADCsThe main feature of inter ADC is fast speed, which is the fastest of all types. The sampling rate can reach above 1GSPS. However, due to the limitations of power and volume, it is difficult to improve the resolution. The conversion of all bits of the ADC with this structure is completed at the same time, and the conversion time mainly depends on the switching speed of the comparator and the transmission time delay of the encoder. In addition, increasing the output code has little effect on the conversion time, but as the resolution increases, a high-density analog design  requires large number of precision divider resistors and comparator circuits for the conversion. That is to say, the output number is increased by one bit and the number of precision resistors is increased. It is about to double, and the comparator is also approximately doubled.The resolution of the parallel comparison ADC is limited by die size, input capacitance, power, etc. If the accuracy of the parallel comparators does not match, it will also cause static errors and increase the input offset voltage. Sigma-delta (Σ-Δ) ADCsThe Sigma-delta (Σ-Δ) ADC is composed of an integrator, a comparator, a 1-bit DA converter, and a digital filter. In principle, it is similar to the integral type. The input voltage is converted into a time (pulse width) signal and processed by a digital filter to obtain a digital value.Figure 2. Analog to Digital Converter Application ExampleⅢ What A/D Converter Includes?1) Sampling RateThe sampling rate indicates the rate at which the analog signal is converted into a digital signal, which is related to the manufacturing technology of the ADC device and depends on the judgment ability provided by the comparator in the ADC.Generally speaking, the sampling rate and resolution are mutually restrictive. Each time the sampling rate is doubled, the resolution losses 1bit. This is mainly due to the jitter during sampling, that is, aperture jitter or aperture uncertainty. 2) ADC ResolutionThe resolution indicates the number of bits after the analog signal is converted into a digital signal. It directly determines the quantization level of the ADC, that is, the minimum analog signal level value that the ADC can distinguish. Assuming that the ADC's input voltage range is (−V, V) and the resolution is N (bit), then the ADC has a 2N quantization level, so that the quantization level is: ΔV=2V/2N, where ΔV is the conversion accuracy. It can be seen from the above formula that the higher the resolution of the ADC and the smaller the voltage input range, the higher its conversion accuracy. 3) Signal-to-Noise Ratio (SNR)The signal-to-noise ratio (SNR) of the ADC reflects the ratio of the root mean square value of the noise-free signal part generated during the quantization process to the root mean square value of the quantization noise. If the input signal is a normalized sine wave 1/2sin(ωt+ψ), the SNR can be determined by the following formula: Among them, N is the resolution of ADC. It can be seen that the signal-to-noise ratio of the ADC mainly depends on the resolution. Every time the resolution increases by one bit, the SNR will increase by 6dB. However, as the resolution increases, the quantization level of the ADC becomes smaller, and the sampling process is more likely to be disturbed. 4) Effective Number of Bits (ENOB)ENOB is a measure of the dynamic range of an ADC converter. For the actual A/D conversion system, due to the influence of factors such as electrical noise, external interference, and non-linear distortion of analog circuits, it is not enough to measure system performance with ideal resolution. In order to better reflect the system performance, on the basis of the measured SNR, the above factors can be converted into quantization noise to get the ENOB. The calculation formula is as follows: ENOB is based on the equation for an ideal ADC's SNR: SNR = 6.02 × N + 1.76 dB, where N is the ADC's resolution.The difference between ENOB and ADC resolution reflects the degree of decrease in sampling accuracy caused by the decrease in SNR(here SNR caused by the error source). 5) Non-Linearity ErrorNon-linear error is an important accuracy index of the converter, which represents the difference between the actual conversion value of the ADC and the theoretical conversion value. Non-linear errors mainly include two types: Differential Non-Linearity (DNL) errors and Integral Non-Linearity (INL) errors. 6) Inter Modulation Distortion (IMD)When two sinusoidal signals are input to the ADC at the same time, due to the nonlinearity of the device, except the components of these two frequencies, the output spectrum will also produce many distortion products. The resulting distortion is called inter modulation distortion ( IMD, Inter Modulation Distortion), where the value of m+n represents the order of distortion. Among all inter-modulation distortions, the second-order and third-order inter-modulation products are the most important. The former is easily filtered out by a digital filter, while the latter is difficult to filter out. 7) Total Harmonic Distortion (THD)Due to the nonlinearity of the ADC, many high-order harmonics of the input signal appear in the output spectrum. These high-order harmonic components are called harmonic distortion components, and the resulting distortion is called Total Harmonic Distortion. Harmonic distortion and modulation distortion are two different concepts. The former is a distortion of the original signal waveform, even if a single frequency signal passes through the ADC, this phenomenon will occur, while the latter is mutual interference and influence between different frequencies.Figure 3. ADC on the ArduinoⅣ A/D Converter Applications and ICs4.1 Analog-to-Digital Converter ApplicationsMost ADC applications today belong to Four Segments: (a) Data acquisition(b) Precision industrial measurement(c) Voiceband and audio(d) High speed (sampling rates greater than about 5 MSPS)4.2 Analog-to-Digital Converter IC Modes ExplainedThere are many ADC ICs available in the market which can be used along to do conversion. Here lists several ADC ICs and their features and specifications as ADC selection references.⭕AD762116-Bit, 2 LSB INL, 3 MSPS PulSAR® ADC, High sampling rate, Available in a 48-lead LQFP or a 48-lead LFCSP⭕AD764118-Bit, 2 MSPS, Charge Redistribution SAR ADC 16 Bits Resolution with No Missing CodesNo Pipeline Delay ( SAR architecture )Differential Input Range: ±VREF (VREF up to 2.5V)Throughput:  3 MSPS (Wideband Warp and Warp Mode)  2 MSPS (Normal Mode)  1.25 MSPS (Impulse Mode)INL ±2 LSB Max (±30 ppm of FS)SINAD: 89 dB Typ @ 100 kHzTHD: -103 dB Typ @ 100 kHzParallel (16 or 8 bits bus) and Serial 5 V/3.3 V/2.5 V InterfaceSPI®/QSPI™/MICROWIRE™/DSP CompatibleOn-board Low Drift Reference with Buffer and Temperature SensorSingle 2.5 V Supply OperationPower Dissipation: 70 mW Typ @ 3 MSPS With REF18-bit resolution with no missing codes2.5 V internal low drift referenceThroughput:  2 MSPS (Warp mode)  1.5 MSPS (Normal mode)Differential input range: ± VREF (VREF up to 2.5 V)INL: ±2 LSB typicalNo pipeline delay (SAR architecture)Parallel (18-, 16-, or 8-bit bus)Serial 5 V/3.3 V/2.5 V interfaceSPI®/QSPI™/MICROWIRE™/DSP compatibleOn-board low drift reference with buffer and temperature sensor ⭕AD79088-Channel, 1 MSPS, 8-Bit ADC with Sequencer in 20-Lead TSSOP⭕AD79188-Channel, 1 MSPS, 10-Bit ADC with Sequencer in 20-Lead TSSOPFast throughput rate: 1 MSPSSpecified for AVDD of 2.7 V to 5.25 VLow Power:  6.0 mW max at 1 MSPS with 3 V supply  13.5 mW max at 1 MSPS with 5 V supplyEight (single-ended) inputs with sequencerWide input bandwidth: AD7928, 70 dB min SINAD at 50 kHz input frequencyFlexible power/serial clock speed managementNo pipeline delaysHigh speed serial interface SPI®/QSPI™/MICROWIRE™/DSP compatibleFast throughput rate: 1 MSPSSpecified for AVDD of 2.7 V to 5.25 VLow Power:  6.0 mW max at 1 MSPS with 3 V supply  13.5 mW max at 1 MSPS with 5 V supplyEight (single-ended) inputs with sequencerWide input bandwidth: AD7928, 70 dB min SINAD at 50 kHz input frequencyFlexible power/serial clock speed managementNo pipeline delaysHigh speed serial interface SPI®/QSPI™/MICROWIRE™/DSP compatible ⭕AD79288-Channel, 1 MSPS, 12-Bit ADC with Sequencer in 20-Lead TSSOP⭕AD5555Precision DUAL 16-Bit 14-Bit-DACs in Compact TSSOP PackagesFast throughput rate: 1 MSPSSpecified for AVDD of 2.7 V to 5.25 VLow Power:  6.0 mW max at 1 MSPS with 3 V supply  13.5 mW max at 1 MSPS with 5 V supplyEight (single-ended) inputs with sequencerWide input bandwidth: AD7928, 70 dB min SINAD at 50 kHz input frequencyFlexible power/serial clock speed managementNo pipeline delaysHigh speed serial interface SPI®/QSPI™/MICROWIRE™/DSP compatible14-bit resolution±1 LSB DNL monotonic±1 LSB INL2 mA full-scale current ±20%, with VREF = 10 V0.5 μs settling time2Q multiplying reference-input 6.9 MHz BWZero or midscale power-up presetZero or midscale dynamic reset3-wire interfaceCompact TSSOP-16 package ⭕AD823016 V Rail-to-Rail, Zero-Drift, Precision Instrumentation Amplifier⭕AD77993-Channel, Low Noise, Low Power, 24-Bit, Sigma Delta ADC with On-Chip In-AmpResistor programmable gain range: 101 to 1000Supply voltage range: ±4 V to ±8 VRail-to-rail input and outputMaintains performance over −40°C to +125°CExcellent ac and dc performance  110 dB minimum CMR @ 60 Hz, G = 10 to 1000  10 μV maximum offset voltage (RTI, ±5 V operation)  50 nV/°C maximum offset drift  20 ppm maximum gain nonlinearityRMS noise:  27 nV at 4.17 Hz (AD7799)  65 nV at 16.7 Hz (AD7799)  40 nV at 4.17 Hz (AD7798)  85 nV at 16.7 Hz (AD7798)Current: 380 μA typicalPower-down: 1 μA maximumLow noise, programmable gain, instrumentation ampUpdate rate: 4.17 Hz to 470 Hz 3 differential inputsInternal clock oscillatorSimultaneous 50 Hz/60 Hz rejectionReference detectLow-side power switchProgrammable digital outputsBurnout currentsPower supply: 2.7 V to 5.25 V ⭕AD944414-Bit, 80 MSPS A/D Converter⭕AD944514-Bit, 105 MSPS / 125 MSPS A/D Converter80 MSPS guaranteed sampling rate100 dB two-tone SFDR with 69.3 MHz and 70.3 MHz73.1 dB SNR with 70 MHz input97 dBc SFDR with 70 MHz inputExcellent linearity  DNL = ±0.4 LSB typical  INL = ±0.6 LSB typical1.2 W power dissipation3.3 V and 5 V supply operation2.0 V p-p differential full-scale inputLVDS outputs (ANSI-644 compatible)Data format selectOutput clock available125 MSPS guaranteed sampling rate (AD9445BSV-125)100 dB two-tone SFDR with 30 MHz and 31 MHz73.5 dB SNR with 70 MHz input85 dBc SFDR with 225 MHz inputExcellent linearity  DNL = ±0.25 LSB typical  INL = ±0.8 LSB typical2.3 W power dissipation3.3 V and 5 V supply operation2.0 V p-p to 3.2 V p-p differential full-scale inputLVDS outputs (ANSI-644 compatible) or CMOS outputsData format select (Offset Binary or 2’s compliment)Output clock available ⭕AD944616-Bit, 80 MSPS / 100 MSPS A/D Converter⭕AD923512-Bit, 20/40/65 MSPS, 3 V Analog-to-Digital Converter100 MSPS guaranteed sampling rate (AD9446-100)83.6 dBFS SNR with 30 MHz input(3.8 V p-p input, 80 MSPS)82.6 dBFS SNR with 30 MHz input(3.2 V p-p input, 80 MSPS)89 dBc SFDR with 30 MHz input(3.2 V p-p input, 80 MSPS)95 dBFS 2-tone SFDR with 9.8 MHz and10.8 MHz (100 MSPS)l 60 fsec rms jitterExcellent linearity  DNL = DNL = ±0.4 LSB typical  INL = ±3.0 LSB typical2.0 V p-p to 4.0 V p-p differential full-scale inputBuffered analog inputsLVDS outputs (ANSI-644 compatible) or CMOS outputsData format select (offset binary or twos complement)Output clock available3.3 V and 5 V supply operationSingle +3 V Supply Operation (2.7 V to 3.6 V)SNR = 70 dBc to Nyquist at 65 MSPSSFDR = 85 dBc to Nyquist at 65 MSPSLow Power: 300 mW at 65 MSPSOn-Chip Reference and SHADifferential Input with 500 MHz BandwidthDNL of ±0.4 LSBFlexible Analog Input: 1 V p-p to 2 V p-pOffset Binary or Twos Complement Data FormatClock Duty Cycle StabilizerPin out Migration to Either AD9215, AD9236, AD9245 Frequently Asked Questions about Analog to Digital Converter (ADC Basic)1. What is the use of analog to digital converter?Analog-to-digital converters, abbreviated as “ADCs,” work to convert analog (continuous, infinitely variable) signals to digital (discrete-time, discrete-amplitude) signals. In more practical terms, an ADC converts an analog input, such as a microphone collecting sound, into a digital signal. 2. What are the types of analog to digital converters?There are really five major types of ADCs in use today:Successive Approximation (SAR) ADCDelta-sigma (ΔΣ) ADCDual Slope ADCPipelined ADCFlash ADC 3. Which chip is used in analog to digital?An A/D converter is used to convert an analog signal like voltage to digital form so that it can be read and processed by a microcontroller. Some microcontrollers have built-in A/D converters. It is also possible to connect an external A/D converter to any type of microcontroller. 4. Which circuit is used in analog to digital converter?Analog to Digital Converter (ADC) is an electronic integrated circuit used to convert the analog signals such as voltages to digital or binary form consisting of 1s and 0s. Most of the ADCs take a voltage input as 0 to 10V, -5V to +5V, etc., and correspondingly produces digital output as some sort of a binary number.

Introduction Diodes are widely used in electronics, such as rectification in power supply, as detection and mixing, etc. in communications, and are often used in voltage regulation and protection in various circuits (such as freewheeling diodes, TVS and so on). Due to the wide variety and versatility, the following is an analysis of the simple application of Schottky diodes in digital circuits.In this video, the Schottky diode has been explained.CatalogIntroductionⅠ Schottky Diodes CharacteristicsⅡ Schottky Diode Applications2.1 As Dual Power Supply2.2 As AND Gate2.3 As OR GateⅢ Schottky Diode ParametersⅣ Example AnalysisⅠ Schottky Diodes CharacteristicsThe Schottky diode is structurally different from the PN junction diode. It is made of an anode metal (a barrier layer made of a material such as molybdenum or aluminum), SiO2 (electric field eliminating material), and N- epitaxial layer (arsenic material), the N-type silicon substrate, N+ cathode layer, and the cathode metal, which are as shown in the following figure. A Schottky barrier is formed between the N-type substrate and the anode metal. When a forward bias is applied to both ends of the Schottky barrier (anode metal is connected to the positive electrode of the power supply, and the N-type substrate is connected to the negative electrode), the Schottky barrier layer is narrowed, and the internal resistance becomes small. On the contrary, when a reverse bias is applied across the Schottky barrier, it becomes wider and its internal resistance becomes larger. Figure 1. Schottky Diode Structure Ⅱ Schottky Diode ApplicationsThe problem with Schottky diodes is that the withstand voltage is relatively low and the reverse leakage current is large. At present, the general condition of the Schottky diode used in the power conversion circuit is that the withstand voltage is below 150V, the average current is below 100A, and the reverse recovery time is between 10 and 40ns. Therefore, Schottky diodes are ideal device for use in high frequency and low voltage circuits.2.1 As Dual Power SupplyAt present, in the electronic design with the main controller, the real-time clock (RTC) is basically used, and the RTC needs an additional button battery to support, to avoid information lost after the system is powered off. And meanwhile, after the system is started, in order to extend the battery life, the main system is often supplied with power. Therefore, RTC often requires dual power supply, and the diode can be used for power isolation due to its single-conductivity. Taking the small-signal Schottky diode BAT54C as an example, the forward voltage drop is only 0.24v (the forward current is 0.1mA), and the RTC current consumption is uA-level, after adding the Schottky diode to isolate power supply to save info security.2.2 As AND GateAs shown in the figure below, n Schottky diodes form the AND gate of the n input. As long as there is a signal output logic 0 in A1~An, the Output is logic 0, only all signals in A1~An output logic 1, Output can output logic 1. That is, the phase sum of the signals A1~An is realized. Since the chip signal input stage is basically high-resistance in the digital circuit, the overall current of the AND gate circuit composed of the Schottky diode is uA-level, and the Schottky diode voltage drop is extremely small. In the case of it, the flat can still meet the design requirements.  Figure 2. Schottky Diode as AND Gate2.3 As OR GateAs shown in the figure below, n Schottky diodes form an n-input OR gate. As long as there is a signal output logic 1 in A1~An, Output outputs a logic 1. Only all signals in A1~An output logic 0, and Output can output logic 0. That is, the phase sum of the signals A1~An is realized.  Figutre 3. Schottky Diode as OR Gate Ⅲ Schottky Diode ParametersNote: Because Schottky diodes are used differently in different electronic circuits, we also need to consider the following parameters when using them.1）Forward voltage drop VFVF is the forward voltage drop when the diode is forward conducting. The greater the current through the diode, the larger the VF, in addition, the higher the diode temperature, the smaller the VF.2）Reverse saturation drain current IRIR refers to the current flowing through the diode when a reverse voltage is applied to the diode. The Schottky diode has a large reverse leakage current, therefore, selecting a Schottky diode with a smaller IR.3）Rated current IFIt refers to the average current value calculated from the allowable temperature rise when the diode is in a long time operation.4）Maximum surge current IFSMExcessive forward current that is allowed to flow. It is not a normal current, but an instantaneous current, which is quite large.5）Maximum peak inverse voltage VRMEven if there is no reverse current, as long as the reverse voltage is continuously increased, the diode will be damaged sooner or later. This reverse voltage is not the instantaneous voltage, but the reversed voltage that is added repeatedly. Since the rectifier is supplied with an alternating voltage, its maximum value is a specified important factor. And the maximum reverse peak voltage VRM refers to the maximum reverse voltage that can be applied to avoid breakdown. At present, Schottky's highest VRM value is 150V.6）Maximum DC reverse voltage VRVR is the value when the DC voltage is continuously applied. For DC circuits, the maximum DC reverse voltage is important to determine the allowable and upper limits.7）Maximum operating frequency FMDue to the junction capacitance of the PN junction, when the operating frequency exceeds a certain value, its unidirectional conductivity will deteriorate. And Schottky diodes have high FM values up to 100 GHz.8）Reverse recovery time TrrWhen the operating voltage changes from a forward voltage to a reverse voltage, the ideal operation of the diode is that the current can be instantaneously turned off. In fact, it usually takes a little delay. The amount that determines the current cut-off delay is the reverse recovery time. Although it directly affects the switching speed of the diode, it does not mean that this value is small. That is, when the diode is suddenly reversed by conduction, the reverse current is greatly attenuated to a time required to approach IR. This indicator is important when the high-power switch is operating in the high-frequency state.9）Maximum dissipation power PWhen a current flows through the diode, it absorbs heat and raises its temperature. In reality, the external heat dissipation condition also has a great influence on P. Specifically, the voltage applied across the diode is multiplied by the current flowing through and the reverse recovery loss. Schottky Diode Symbols Ⅳ Example AnalysisIn digital circuit design, it is often necessary to make simple phase, or phase inversion of some signals. If the logic chip such as the 74 series is directly used, not only the layout area is greatly increased, but also the wiring is not flexible. The use of small-signal Schottky diodes and OR gates is more flexible and easy to use. The following figure shows a simple two-way reset circuit. JTAG generating a reset signal needs to reset the master, and the external reset button also needs to reset the master when pressed. If the JTAG reset and button reset directly to the reset pin of the master, it may cause damage to the JTAG emulator. For example, when the reset button is pressed, the JTAG output reset pin will be directly lowered. The phase and circuit are formed by the Schottky diode BAT54A , and the signal outputs do not affect each other. The following figure allows the master to reset as long as the JTAG output logic 0 or pressing the button reset output logic 0.Figure 4. Schottky Diode BAT54A ApplicationIf it is to be used as a non-gate, a triode can be used. Of course, the triode is widely used in electronics, such as a switching device in a digital circuit, as a current drive, level shifter, and the like. Frequently Asked Questions about Small Signal Schottky Diodes1. What is the Schottky diode and how it works?A typical diode combines p-type and n-type semiconductors to form a p-n junction. In a Schottky diode metal replaces the p-type semiconductor. This metal can range from platinum to tungsten, molybdenum, gold, etc. When metal is combined with an n-type semiconductor an m-s junction is formed. 2. What does small signal mean?A small signal is an AC signal (more technically, a signal having zero average value) superimposed on a bias signal (or superimposed on a DC constant signal). This resolution of a signal into two components allows the technique of superposition to be used to simplify further analysis. 3. Which statement is correct for Schottky diode?Explanation: The majority charge carriers in a Schottky diode are electrons not holes. Explanation: Due to the metal-silicon junction there are no stored charges hence, no reverse recovery time, due to which the switching is faster. 4. What are the two important features of a Schottky diode?We have seen here that the Schottky Diode also known as a Schottky Barrier Diode is a solid-state semiconductor diode in which a metal electrode and an n-type semiconductor form the diodes ms-junction giving it two major advantages over traditional pn-junction diodes, a faster switching speed, and a low forward bias.

I IntroductionThe light-emitting diode is a commonly used light-emitting device, which emits energy through the recombination of electrons and holes. It is widely used in the field of lighting. Light-emitting diodes can efficiently convert electrical energy into light energy. Light-emitting diodes have a wide range of uses in modern society, such as lighting, flat panel displays, and medical devices.Light Emitting Diode (LED) Working PrincipleThis kind of electronic component appeared as early as 1962. In the early days, it could only emit low brightness red light. Later, other versions of monochromatic light were developed. The light that can be emitted today has spread to visible light, infrared light, and ultraviolet light. Initially,  the light-emitting diodes were used as indicator lights, display panels, etc. With the continuous progress of technology, light-emitting diodes have been widely used in displays and lighting.CatalogI IntroductionII Parameters of Light-emitting Diode2.1 Significance of Limit Parameters2.2 Significance of Electrical ParametersIII Working Principle of Light-emitting DiodeIV Types of Light-emitting DiodeV Materials of a Light-emitting Diode5.1 Wafer5.2 Bracket5.3 Silver glue 5.4 Gold wire 5.5 Epoxy resinVI Applications of Light-emitting Diode6.1 Display Screen and Communication Signal Display6.2 Automotive Industry6.3 LCD Backlight6.4 LED Lighting6.5 Other ApplicationsVII Trends of LED Lighting TechnologyII Parameters of Light-emitting Diode2.1 Significance of Limit Parameters(1) Allowable power consumption Pm: the maximum value of the product of the forward DC voltage applied to both ends of the LED and the current flowing through it. If this value is exceeded, the LED becomes hot and damaged.(2) Maximum forward DC current IFm: the maximum forward DC current allowed to be added. Exceeding this value can damage the diode.(3) Maximum reverse voltage VRm: the maximum reverse voltage allowed to be applied. Above this value, the light-emitting diode may be damaged by the breakdown.(4) Working environment topm: the ambient temperature range where the LED can work normally. Below or above this temperature range, the light-emitting diode will not work properly and the efficiency is greatly reduced.2.2 Significance of Electrical Parameters(1) Spectral distribution and peak wavelength: the light emitted by a certain light-emitting diode is not a single wavelength, and its wavelength is generally shown in Figure.Figure 1. Spectral Distribution and Peak WavelengthIt can be seen from the figure that the light intensity of a certain wavelength λ0 in the light emitted by the light-emitting tube is the largest, and this wavelength is the peak wavelength.(2) Luminous intensity IV: The luminous intensity of the light-emitting diode usually refers to the luminous intensity in the direction of the normal. When the radiation intensity in this direction is (1/683) W / sr, it emits 1 candela (symbol cd). Since the general LED has a low luminous intensity, the luminous intensity is usually measured in candela (mcd).(3) Spectral half-width Δλ: It represents the spectral purity of the light-emitting tube. It refers to the interval between the two wavelengths corresponding to the 1/2 peak light intensity in Figure 3.(4) Half value angle θ1 / 2 and viewing angle: θ1 / 2 refers to the angle between the direction in which the luminous intensity value is half of the axial intensity value and the luminous axis (normal direction).Two times the half-value angle is the viewing angle (or half-power angle).Figure 2. Angle Distribution of Luminous Intensity of the LEDFigure above shows the angular distribution of the luminous intensity of two different types of LEDs. The coordinates of the perpendicular (normal) AO are the relative luminous intensity (ie, the ratio of the luminous intensity to the maximum luminous intensity). Obviously, the relative luminous intensity in the normal direction is 1. The larger the angle away from the normal direction, the smaller the relative luminous intensity. From this graph, the half-value angle or viewing angle value can be obtained.(5) Forward working current If: It refers to the forward current value when the light-emitting diode is normally emitting light. In actual use, the IF should be selected below 0.6·IFm.(6) Forward working voltage VF: The working voltage given in the parameter table is obtained under a given forward current. Generally measured at IF = 20mA. The forward working voltage VF of the light-emitting diode is 1.4 ~ 3V. When the outside temperature increases, VF will decrease.(7) V-I characteristics: The relationship between the voltage and current of the light-emitting diode can be represented in the figure below.Figure 3. The Relationship between the Voltage and Current of the LEDWhen the forward voltage is less than a certain value (called a threshold), the current is extremely small and does not emit light. When the voltage exceeds a certain value, the forward current increases rapidly with the voltage and emits light. From the V-I curve, parameters such as the forward voltage, reverse current, and reverse voltage of the light-emitting tube can be obtained. The forward leakage current IR of the LED tube is less than 10μA.III Working Principle of Light-emitting DiodeThe core part of the light-emitting diode is a wafer composed of a P-type semiconductor and an N-type semiconductor. There is a transition layer between the P-type semiconductor and the N-type semiconductor, called a PN junction. In the PN junction of some semiconductor materials, the injected minority carriers and majority carriers will release excess energy. The energy is in the form of light, thereby directly converting electrical energy into light energy. The reverse voltage is added to the PN junction. Minority carriers are difficult to inject, so they do not emit light. This kind of diode is called a light-emitting diode, commonly known as LED. When it is in the forward working state (that is, the forward voltage is applied to both ends), and when the current flows from the anode to the cathode of the LED, the semiconductor crystal emits light of different colors from ultraviolet to infrared. The intensity of the light is related to the current.The principle of light-emitting diode needs to be analyzed from the following three situations:When no voltage is applied across the diode, the electrons in the N-type material will move along the PN junction between the layers. The electrons fill the holes in the P-type material and form a depletion region. In the depletion region, the semiconductor material returns to its original insulation state. That is, all holes are filled, so there is neither free electrons nor space for electrons to move in the depletion region, and the charge cannot flow.Figure 4. No Voltage is Applied Across the DiodeWhen a forward voltage is applied to the light-emitting diode, the holes injected from the P region to the N region. And the electrons injected from the N region into the P region within a few microns near the PN junction. They recombine with electrons in the N region and holes in the P region respectively. Therefore, they produce spontaneously emitted fluorescence. Different semiconductor materials have different energy states for electrons and holes. The more energy released, the shorter the wavelength of the emitted light. Diodes that emit red, green, or yellow light are commonly used.Figure 5. Apply a Forward Voltage to the LEDWhen a reverse voltage is applied to the light-emitting diode, the P-type terminal is connected to the negative electrode of the circuit, and the N-type terminal is connected to the positive electrode. And the current will not flow. Negatively charged electrons in N-type materials will be attracted to the positive electrode. Positively charged holes in P-type materials will be attracted to the negative electrode. Since holes and electrons move in the wrong direction. No current will flow through the PN junction, and the depletion region will also expand.Figure 6. Apply a Reverse Voltage to the LED LED materialColorAlGaAs GaAsP AlGaInP GaP:ZnOred and infrared InGaN/GaN GaP AlGaInP AlGaPgreenGaAsPAlGaInP AlGaInP GaPhigh brightness orange red, orange, yellow, greenGaAsPred, orange, yellowGaP ZnSe InGaN SiCred, yellow, greenGaNgreen, emerald green, blueInGaNnear ultraviolet, blue green, blueSiCblueSiblueAl2O3blueZnSeblueCultravioletAlN AlGaNUV with wavelengths far to nearTable: Inorganic Semiconductor Materials Used in Light-emitting Diodes and the Colors They EmitIV Types of Light-emitting DiodeThere are various types of light-emitting diodes according to different aspects. According to the materials used, there are gallium phosphide (GaP) light-emitting diodes, phosphorous gallium arsenide (GaAsP) light-emitting diodes, gallium arsenide (GaAs) light-emitting diodes, phosphorous indium gallium arsenide (GaAsInP) light-emitting diodes and gallium arsenide aluminide (GaAlAs) light-emitting diodes.According to its packaging structure and packaging form, there are metal packaging, ceramic packaging, plastic packaging, resin packaging, and leadless surface packaging. It can also be divided into additive color scattering package (D), colorless scattering package (W), colored transparent packaging (C), and colorless transparent packaging (T).Figure 7. Kinds of Light-emitting DiodeAccording to its package shape, it can be divided into circular, square, rectangular, triangular, and combined shapes. The figure shows the shape of several light-emitting diodes.Plastic light-emitting diodes are divided into red, amber, yellow, orange, light blue, green, black, white, transparent, and colorless according to the color of the tube body. The outer diameter of the round light-emitting diode is from ￠ 2 to ￠ 20mm. According to the light-emitting color of the light-emitting diodes, it can also be colored light and infrared light. Colored lights include red light, yellow light, orange light, green light, and so on. In addition, light-emitting diodes can be divided into ordinary monochrome light-emitting diodes, high-brightness light-emitting diodes, ultra-high-brightness light-emitting diodes, color-changing light-emitting diodes, flashing light-emitting diodes, voltage-controlled light-emitting diodes, infrared light-emitting diodes, and negative resistance light-emitting diodes.V Materials of a Light-emitting DiodeWafer, bracket, silver glue, gold wire, and epoxy resin are the five LED raw materials of light-emitting diode5.1 WaferThe structure of the wafer: it consists of a gold pad, P-pole, N-pole, PN junction, and a back gold layer (the double-pad wafer has no back gold layer). The wafer is composed of P-layer semiconductor elements and N-layer semiconductor elements. They are rearranged and combined by electron movement. It is this change that enables the wafer to be in a relatively stable state. When the positive electrode is applied to the wafer with a certain voltage, the holes in the positive P region will continue to swim toward the N region. And the electrons in the N region will move to the P region relative to the holes. While the electrons and holes move relatively, the electron holes pair with each other, exciting photons and generating light energy.The main classification of wafer: surface-emitting type: most of the light is emitted from the surface of the wafer. Five-sided light-emitting type: there is more light emitted on the surface and side.5.2 BracketThe structure of the bracket is 1 layer of iron, 1 layer of copper (good conductivity, fast heat dissipation), 1 layer of nickel (anti-oxidation), 1 layer of silver (good reflectivity, easy to solder wire)5.3 Silver glue Take H20E as an example. Silver glue is also called white glue, milky white. The role of silver glue is to conduct and bond materials (baking temperature: 100°C / 1.5H). Storage conditions: Silver glue manufacturers generally store silver glue at -40°C, and application units generally at -5°C. Single-agent is 25°C / 1 year (dry, ventilated place), mixed agent 25°C / 72 hours. Baking conditions: 150°C / 1.5H. Stirring conditions: Mix for 15 minutes in one direction.5.4 Gold wire Take φ1.0mil as an example. The gold wires used for LEDs are φ1.0mil and φ1.2mil. The material of the gold wire is generally 99.9% of the gold content of the gold wire for LED. The purpose of the gold wire: with its characteristics such as high gold content, soft, easy to deform, good conductivity and good heat dissipation, a closed circuit is formed between the wafer and the bracket. (Conversion relationship: 1 mil = 0.0254mm, 1 in = 25.4mm)5.5 Epoxy Resin Ttake EP400 as an example. Composition: A and B two parts: Glue A: it is the main agent, which consists of epoxy resin + defoamer + heat resistance agent + thinner. Agent B: it is a curing agent, consisting of acid, mold release agent, and accelerator.VI Applications of Light-emitting Diode6.1 Display Screen and Communication Signal DisplayLED lamp has the characteristics of shock resistance, fast light response, power-saving, and long life, etc. It is widely used in various indoor and outdoor displays. It is divided into full-color, three-color, and monochrome displays that are developed and produced by more than 100 units nationwide. Traffic lights mainly use ultra-high-brightness red, green, and yellow LEDs. Because LED lights are energy-saving and reliable, the traffic lights are gradually being replaced throughout the country and the speed of promotion is fast.Figure 8. Traffic Lights6.2 Automotive IndustryAutomotive lamps include dashboards, audio indicators, backlights for switches, reading lights and external brake lights, tail lights, sidelights, and headlights. Incandescent lamps for automobiles are not resistant to shock that require frequent replacement. Due to the fast response speed of the LED, the driver can be reminded of the brakes early to reduce the rear-end accident. In developed countries, the central rear high-position brake light made of LED has become a standard part of the car. The LED car tail light model launched by the American HP company in 1996 Groups can be combined into various car taillights at will. In addition, the light sources in the car dashboard and other various lighting parts can be used as ultra-high brightness light-emitting lamps. In recent years, an annual output value of 1 billion yuan will be formed, and within 5 years, an annual output value of 3 billion yuan will be formed.Figure 9. Automotive Headlight6.3 LCD BacklightLED backlights are most noticeable with high-efficiency side-emitting backlights. As an LCD backlight application, LEDs have the characteristics of long life, high luminous efficiency, no interference, and high-cost performance. They have been widely used in electronic watches, mobile phones, BP, computers, electronic calculators, and credit card machines. With the increasing miniaturization of portable electronic products, the LED backlight has more advantages.  The backlights manufacturing technology will be developed to thinner, low power consumption, and uniformity. LED is the key device of a mobile phone. An ordinary mobile phone needs about 10 LED devices, while a color screen and a mobile phone with camera function need to use about 20 LED devices. At present, the amount of mobile phone backlight is very large. 3.5 billion LED chips are used a year.6.4 LED Lighting  Early lighting products have low luminous efficiency. The light intensity can only reach a few to dozens of mcd, which is suitable for indoor occasions, such as home appliances, instrumentation, communication equipment, microcomputers, and toys. At present, the direct goal is to replace incandescent lamps and fluorescent lamps with LED light sources. This substitution trend has started to develop from local application fields. To save energy, Japan is planning to replace the incandescent light-emitting diode project (called "illuminate Japan"). The budget for the first five years is 5 billion yen. If LED replaces half of the incandescent and fluorescent lamps, the annual savings can be equivalent to the energy of 6 billion liters of crude oil. That is equivalent to the power generation of five 1.35 × 106kW nuclear power plants. It can reduce the production of carbon dioxide and other greenhouse gases and improve the living environment.6.5 Other ApplicationsFigure 10. LED Christmas LightsOther applications such as a kind of flash shoes popular with children, the built-in LED will flash when walking; the power indicator of electric toothbrushes; the popular LED Christmas lights. Due to the novel shape, rich colors, unbreakable and low-voltage safety Sexuality, LED Christmas light is generally welcomed by people. It is threatening and replacing the existing Christmas market of electric bulbs.VII Trends of LED Lighting Technology1. The mainstream light source of lighting will be converted to LED. At present, the luminous efficiency of high-power led commercial products has reached more than 150lm / W. The life span has reached more than 30,000 hours. The comprehensive performance of LEDs has exceeded other light sources. At the same time, in addition to large power, the price of LED lamps is close to lamps composed of other light sources. Therefore, LED already has certain advantages. At the same time, the light efficiency of LED laboratory products has reached more than 300lm / W. Through a reasonable heat dissipation design, the life span of more than 50,000 hours can be fully achieved. In principle, there is not much room for other light sources to improve light efficiency and life. Therefore, it can be expected that LED becoming the mainstream light source in the lighting market.2. The research of LED device technology will mainly focus on the improvement of green LED efficiency. The core device of semiconductor technology-LED, currently the red LED and the blue LED has high photoelectric efficiency, but the photoelectric efficiency of the green LED is very low. This limits the substantial application of LED spectral flexibility. Therefore, improving the light efficiency of green LEDs is the most important research topic of LED devices.3. Another study of LED technology will be the study of narrow-spectrum LED devices. The narrow spectral width of a single LED will help to truly achieve unlimited flexibility in assembling the LED spectrum. At the same time, one of the main applications of LEDs at present-LED displays, if the spectral width of monochromatic LEDs can be reduced, a larger color gamut space can be achieved.4. White LEDs for general lighting will gradually shift to RGB mode. The light sources used for general lighting are presented in the form of white light or near-white light. At present, the most comprehensive and cost-effective white LEDs on the market are also implemented by blue LEDs and YAG phosphors. However, the RGB method has higher light efficiency. It will enable the lamp to be dimmed, toned, and even adjusted the color rendering index. Therefore, with the improvement of green LED light efficiency, it is believed that the RGB method (further extended to 3 or more monochromatic LED mixed colors) will become the mainstream white LED mode.5. The characterization of the color rendering of the light source will be a long-term debate. The characterization in the form of the spectrum may be the ultimate result. The current parameter that characterizes the color rendering of the light source is the color rendering index. However, this is based on the limited spectral form of traditional light sources. The infinite flexibility of the LED spectrum will make this characterization problematic. It can be predicted that if the LED achieves true spectrum unlimited flexibility. Any single-parameter color rendering will actually be flawed, and the ultimate characterization method should be the spectrum itself.6. The application of light sources will include two basic aspects of visual applications and non-visual applications. The flexibility of LEDs in spectral assembly makes it possible to achieve various visual and non-visual optimized applications through spectral assemblies, such as agricultural lighting, medical lighting, LED Visible light communication, etc. But relatively speaking,  in the non-visual field, there are still many problems to be solved, including what kind of lighting conditions are optimized, the price of LED needs to be further reduced. The former is a scientific problem, while the latter is an industrialization problem.7. Lighting technology will be deeply integrated with information technology to create smart lighting. As a semiconductor device, LED is a good physical carrier of information technology because LED is easy to control plus the relevance of lamps and human life. Therefore, LED can be deeply integrated with information technology, and smart lighting will be born. This will be an important development direction for future LED lighting technology.8. The appearance of the lamps and lanterns will have great innovation potential. At present, most LED lamps and lanterns include LED bulbs, LED downlights, LED tubes, etc., all of which are designed to cater to people's consumption habits. Whether this is the best mechanical form of the lamp or not remains to be studied. At least, there is a lot of room for innovation in the future mechanical form of LED lamps.9. OLED will occupy an important position in the display field. Relative to LEDs that emit light similar to point light sources, OLEDs emit light in the form of surface light sources. Therefore, after LED occupies the vast majority of lighting applications in the future, OLED still has certain advantages in the display field.10. Natural lighting will be valued. In recent years, energy-saving lighting, health lighting, and ecological lighting have received great attention. The use of sunlight to achieve lighting naturally becomes the best choice. Therefore, with the advancement of technology, natural light lighting will receive more and more attention.Due to the great flexibility of LEDs in the three dimensions of scale, spectrum, and time, many innovative applications and concepts may be born in the future of LED development. This is the development trend of lighting based on artificial light sources. At the same time, as people continue to deepen the concept of green environmental protection, natural lighting will also get greater development. Frequently Asked Questions about Light-emitting Diode Tutorial1. What does light emitting diode mean?In the simplest terms, a light-emitting diode (LED) is a semiconductor device that emits light when an electric current is passed through it. Light is produced when the particles that carry the current (known as electrons and holes) combine together within the semiconductor material. 2. What is a light emitting diode used for?Light emitting diodes, commonly called LEDs, are real unsung heroes in the electronics world. They do many different jobs in all kinds of devices. They form numbers on digital clocks, transmit information from remote controls, light up watches and tell you when your appliances are turned on. 3. What type of light does LED emit?LED lighting differs from incandescent and fluorescent in several ways. When designed well, LED lighting is more efficient, versatile, and lasts longer. LEDs are “directional” light sources, which means they emit light in a specific direction, unlike incandescent and CFL, which emit light and heat in all directions. 4. Why are LED lights so bright?LED lights are so bright because they have a high lumen/watt score. ... This is an enormous difference between the levels of light you are getting from each bulb and because the LED bulb is so much higher there is no way that you would need to replace a 40W incandescent bulb with the equivalent Watt in a LED. 5. What is the difference between diode and LED?The most significant difference between the LED and diode is that the LED emits the light while the diode allows the current to flow only in one direction and opposes the flow in the opposite direction. 6. What is the basic principle of LED?Working Principle: A light-emitting diode is a two-lead semiconductor light source. It is a p–n junction diode that emits light when activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. 7. Do LED lights give off UVB?Some in the lighting business have stated that LEDs do not produce UV radiation. However studies have shown that standard LEDs do create a small amount of UV. That said, the amount of UV they actually emit is even less. This is due to the phosphors within an LED lamp that convert the Ultraviolet light to white light. 8. What are the two basic types of LEDs?The two basic types of LEDs are indicator-type LEDs and illuminator-type LEDs. Indicator-type LEDs are usually inexpensive, low-power LEDs suitable for use only as indicator lights in panel displays and electronic devices, or instrument illumination in cars and computers. 9. What is LED and its advantages?Safety is perhaps the most often overlooked advantage when it comes to LED lighting. The number one hazard when it comes to lighting is the emission of heat. LEDs emit almost no forward heat while traditional bulbs like incandescents convert more than 90% of the total energy used to power them directly into heat. 10. What is the O in OLED?Organic contrastOLED stands for organic light-emitting diode. Each pixel in an OLED display is made of a material that glows when you jab it with electricity.

PCB printers are able to make PCBs without engraving. they do this by spraying a special type of ink called conductive ink on a flat, hard surface. Printers that can easily print electronic circuits rather than circuit boards are also under development. Top 5 PCB Printing and Prototyping machines for your desktop In this blog, you will see top 5 best PCB printers on your desk, each with their own advantages of use, for users with different printing needs. You can take a quick look at the features of 5  PCB printers below:  - Nano Dimension DragonFly 2020: World’s first 3-D PCB printer  - Voltera V-One: Circuit board prototyping machine  - The Othermill: A desktop CNC mill for electronics  - Voxel8: 3D electronics printing  - Prometheus PCB milling machine Nano Dimension DragonFly 2020 PCB Printer The Nano Dimension DragonFly 2020 PCB printer is touted as the world's first 3-D PCB printer and the first desktop printer to meet IPC guidelines. It can produce PCBs from scratch with a minimum feature size of 80 μm and a maximum of 1.5 mm. the minimum layer thickness is 30 μm or 0.03 mm. the positioning accuracy is 25 μm along any axis. the maximum build size is 200 x 200 x 3 mm. it can produce multilayer PCBs with a total thickness of up to 3 mm. the printer supports many different conductive and dielectric inks. Voltera V-One PCB Printer The Voltera V-One is a printed circuit board printer that is very easy to use and perfect for electronics R&D departments, schools, or researchers. This tool makes it as easy to print circuit boards as it is to print parts. Users build boards faster, using the Voltera V-One printer to prototype project boards on the desktop. The process is as simple as inputting a gerber file into the Voltera software, pressing print, and the V-One will print out a lifelike circuit, then use the spray paste (solder) and reflow features to solder the electronics to the board. The Voltera V-One can be used to -Print circuits: Design, fabricate, test, and recreate circuit cloth -Assemble electronic components: Solder electronic components as small as 0402 to a circuit board with solder paste -Research: Spray and cure your own materials Othermill Pro PCB Printer Othermill Pro is a portable, precise milling machine that allows you to use digital designs to create 2D and 3D objects from durable materials such as wood, metal and plastic. Othermill Pro is essentially for the production of fast double-sided printed circuit boards with trace widths down to 150 μm. positioning accuracy is approximately 75 μm. workpiece sizes up to 140 x 114 mm are possible. One limitation is that harder materials such as glass and FR-4 cannot be used. the Othermill Pro can be used with a wide range of operating systems and PCB software. It is currently only available in the US. Voxel8 PCB Printer The Voxel8 desktop 3D printer was developed based on basic patents related to the University of Illinois and Harvard University and features two different print heads, one based on common FFF/FDM technology using fused wire and the other using conductive silver ink. Functional materials are at the heart of the Voxel8 technology, and according to the company, their silver ink is 20,000 times more conductive than the most conductive thermoplastic wire currently available, and 5,000 times more conductive than carbon-based inks such as Bare Conductive material! Voxel8's specially formulated inks are deposited through a dedicated 250 micron diameter nozzle. Once printed, it dries quickly at room temperature and requires no post-processing. These properties make it possible to print on traditional thermoplastic materials. 3D electronics printing requires the ability to insert multiple components into the printing process. The Voxel8 desktop 3D printer is equipped with a highly repeatable magnetic print bed that enables you to temporarily remove the printed object during the printing process, insert components, such as LEDs or sensors, and then put them back in to continue the printing process. This technology has a wide range of potential uses for printed circuits, 3D polymer scaffolds for tissue engineering and advanced materials for energy harvesting storage, among others. Prometheus PCB milling machine Prometheus: This is not only a 3D printer. The desktop manufacturing space has been dominated by 3D printers for years, but other types of machines (mills, laser cutters, robotic arms, etc.) are bringing prices to amateurs and small businesses. Zippy Robotics founder Rocco Tuccio plans to bring custom printed circuit board (PCB) fabrication to engineers and electronics enthusiasts for about $2,500.The Prometheus is a desktop machine that can create real circuit boards in minutes. Tuccio hopes to provide rapid PCB prototyping capabilities to as many people as possible. What makes Prometheus PCB milling machine different? 1. The extremely small runout error allows you to precisely cut traces down to 7 mils (7 thousand inches), which means you can design with virtually any surface mount component. 2. High spindle speeds allow you to mill 3" x 5" boards in minutes (not hours)! 3. Included software gives you control over the entire tool chain, including the easy-to-use Circuit Factory design software and public API. 4. Prices are a few thousand less than similar precision machines. FAQ 1. What is a PCB in a printer? While design of a printed circuit board (PCB) can be done internally, manufacturing is generally outsourced. This dependence often results in uncontrollable, and unexpected delays. ... It is here that desktop PCB printers are aiming to come to the rescue. 2. How much does it cost to print a PCB? In general, the cost to produce a PCB will cost between $10 and $50 per board. 3. How does a PCB printer work? A special printer called a plotted printer is used to print the design of the PCB. It produces a film that shows the details and layers of the board. When printed, there will be two ink colors used on the inside layer of the board: Clear Ink to show the non-conductive areas. 4.Why are PCB green? It is due to the solder mask, which protects the copper circuits printed on the fibre glass core to prevent short circuits, soldering errors, etc. ... The colour of the solder mask gives the board its appearance. 5. How much does custom PCB cost? At BatchPCB, a two-layer board costs $2.50 per square inch (about $0.40 per square centimeter), while a four-layer board costs $8 for the same area (about $1.24/cm2). The first step in creating a custom PCB is laying out the schematic view. 6. How do I print directly from PCB? A laser printer is used to print an image of the PCB on special “transfer paper” which is then placed on the bare copperclad board and either ironed or run through a modified laminator to transfer the image to the copper. 7. What does PCB stand for? Printed circuit board. A printed circuit board, or PC board, or PCB, is a non-conductive material with conductive lines printed or etched. Electronic components are mounted on the board and the traces connect the components together to form a working circuit or assembly. 8. What is PCB made of? Copper circuitry. Printed circuit boards (PCBs) are usually a flat laminated composite made from non-conductive substrate materials with layers of copper circuitry buried internally or on the external surfaces. They can be as simple as one or two layers of copper, or in high density applications they can have fifty layers or more. 9. Which type of PCB is more economical type? Aluminum-Backed PCBs. Aluminum is inexpensive, making almost 8.23% of planet's weight, and leads to most economical manufacturing process. PCBs made up of aluminum are easily recyclable and non-toxic in nature, making them as ideal source for energy conservation. 10. How do you choose a PCB material? Electrical functionality is based on PCB function, which makes it a good criterion for design-based circuit board material selection. According to function, PCBs may be classified as the following board types: High Frequency (High Speed) – These boards can accommodate frequencies in the 500MHz – 2GHz range.

I IntroductionThis article introduces the basics of low voltage transformer, including the definition of low voltage transformer, the principle of low voltage transformer, its installation method, malfunction, and how to repair a household low voltage transformer. A transformer is an electronic instrument that we can use everywhere in our lives. For example, we are inseparable from the mobile phone chargers. The internal components also have transformers. For example, the power supply in our computers is also composed of transformers. Therefore, all electronic products are indispensable for transformers. The transformers used in electronic components are all power transformers (included low voltage transformers). The power transformer is mainly used in electronic products to convert the power supply to the voltage required by the electronic circuit.CatalogⅠIntroductionⅡ Basics of low voltage transformer2.1 Definition of low voltage transformer2.2 Types of low voltage transformers2.3 How does low voltage transformer work?2.4 Design requirements of low voltage transformer2.5 Application environmentⅢ Differences between low&high voltage transformerⅣ How to Estimate the Loss of Low Voltage TransformerV Guide to What You May be Interested in5.1 How to Install Low Voltage Transformer for Household?5.2 How to Troubleshoot a Low-Voltage Transformer5.3 Repairing a household transformer5.4 Malfunction of factory low voltage transformerVI One Question Related to Low Voltage Transformer6.1 Question (Multiple choice questions)6.2 AnswerVII FAQII Basics of Low Voltage Transformer2.1 Definition of Low Voltage Transformer Transformers are important power equipment in our life, especially low-voltage transformer. Whether it is for large-scale power plants or home circuits, it is inseparable from the transformer. There are two kinds of transformers used in our life, one is the high-voltage transformer which used in the high-voltage or ultra-high-voltage circuit, the other is the low-voltage transformer which used in the family lighting circuit or small power circuit.The so-called low-voltage transformer refers to the transformer with low load voltage. As long as the load is lower than 600V, it can be called a low-voltage transformer. The low-voltage transformer is mainly composed of primary coil, secondary coil, and a magnet iron circuit. Low voltage transformers are commonly used for low voltage lighting, which typically only uses 12 or 24 volts. 2.2 Types of Low Voltage TransformersThere are two main types of low voltage transformers: electronic and magnetic.（1）Electronic Low Voltage TransformersElectronic transformers are much smaller, lighter, and less expensive than magnetic counterparts. But they only have about a 5-6 year lifespan. Also, electronic low voltage transformers are known for being noisy.Electronic Low Voltage TransformersAdvantagesDisadvantages▪ Smaller and lighter, easier to hide▪ Less expensive▪ Shorter life span▪ Noisy▪ Heat-sensitive（2）Magnetic Low Voltage TransformersThere are two types of magnetic transformers: stack laminated and toroidal.  Stack laminated transformers have a longer lifespan, about 15 to 20 years. But they only operate at about 80 to 85 percent efficiency, also are known for being noisy.Toroidal transformers are very quiet and more energy efficient. They can operate at about 90 to 95 percent efficiency. And they are long-lived, lasting 20 to 25 years.Magnetic Low Voltage TransformersAdvantagesDisadvantages▪ Long life span of over 15 years▪ Energy efficient▪ Quiet▪ Heavy, big, and difficult to hide▪ Expensive2.3 How Does Low Voltage Transformer Work?Electricity and magnetism are two kinds of energy that can mutually transform. Electricity can generate magnetism, and magnetism can also generate electricity. The low-voltage transformer uses this principle to adjust the voltage through the mutual conversion of electricity and magnetism.A low voltage transformer consists of two electrical coils of wire, one of which is called primary winding and the other is called secondary winding. The primary side of the transformer collects power and the secondary side provides power.Figure 1. Low Voltage Transformer StructureThe two coils intertwine together on a magnet iron circuit core, but without electrically in contact with each other. The magnetic core is made of soft magnetic material, which consists of laminations connected together to help reduce core loss. The core allows power to be transferred from one coil to another. When the primary winding is connected to the power supply, the generated magnetic field transfers the voltage to the secondary winding.Figure 2.  How Does Low Voltage Transformer Work?In summary, the primary winding transforms the electrical power into magnet field when connected to the input voltage supply while secondary winding transforms alternating magnetic field into electrical power of required output.2.4 Design Requirements of Low Voltage TransformerThe low-voltage transformer should be vacuum cast, molded resin encapsulated, 60Hz, Class F insulation, comply with the requirements of IEC726, and meet the requirements of capacity, voltage, phase number, and wiring shown. Each low-voltage transformer has separate primary and secondary windings, and there are two 2.5% normal voltage full-capacity taps above and below the rated voltage on the primary side. The low-voltage transformer should be installed on a base that can isolate, reduce vibration and noise, and the iron core and coil should be properly fixed to withstand the mechanical stress generated in the event of line failure and can withstand 16460 Lite 16460-6 V2. 0 2002/ 11/ 25 Vibration and impact during shipment. Unless otherwise specified, the impedance of low-voltage transformers shall be in accordance with IEC 726. The average noise level of the low-voltage transformer should not exceed the value specified in IEC 726. Each dry-type low-voltage transformer should have appropriate terminals to accommodate the required primary and secondary wiring connections. Low-voltage transformers can be reserved for cable entry from either side or bottom.2.5 Application Environment(1) Ambient air temperature - 5 ℃ to + 40 ℃, 24-houraverage value not more than + 35 ℃(2) The altitude of the installation site shall not exceed 2000m(3) The relative humidity of the atmosphere shall not exceed50% when the ambient air temperature is + 40 ℃(4) A place without violent shaking and impact vibrationIII Differences Between Low&High Voltage Transformer Low Voltage TransformerHigh Voltage Transformerwindingcontinuous windingInterleaved WindingscoolingOil-immersed cooling or air coolingOil-immersed coolingstructureoil tank structurebell jar type oil tankⅣ How to Estimate the Loss of Low Voltage TransformerTransformer loss include copper loss and iron loss. The loss of iron loss is also called no-load loss, and the loss of copper loss is also called load loss. The open circuit of the secondary winding of the transformer applies the no-load current of rated frequency and rated voltage to the primary side, and the active loss caused by the transformer core is called the no-load loss of the transformer. The loss figure can be obtained by the unit loss of the iron core silicon steel sheet multiply the quality of the silicon steel sheet. In general, its loss is very small. For example, the S9-100/10 distribution transformer has a no-load loss of 290W. The larger the transformer capacity, the smaller the no-load loss, generally between 0.3-0.15% of the rated capacity. However, the transformer works continuously for 24 hours, and this loss cannot be ignored. The load loss: The short-circuit of the coil on the secondary side apply the rated current at the rated frequency on the primary side. The transformer loss at this time is the loss of the transformer coil and the iron core. Let's take the S9 series transformer as an example and see its load loss value:The load loss of S9-100/10000 transformer is 1500W.The load loss of S9-1000/10000 transformer is 10300W.The load loss of a transformer is generally between 0.9-1.8%. The larger the transformer, the smaller the load loss.V Guide to What You Maybe Interested in 5.1 How to Install Low Voltage Transformer for Household? First, make sure you have an outlet available. Most family homes will have several outdoor power outlets installed. Second, think about the layout of the lighting. It is important to plan ahead when installing low voltage lighting so that you can avoid any potential problems, especially with the setup.Third, choose a transformer.①Magnetic or Electronic.②Make sure to buy a transformer that can handle the lighting load you need it to.Fourth, install the transformer. Transformers are installed simply by plugging them into your outdoor outlet.5.2 How to Troubleshoot a Low-Voltage Transformer(1) First, check whether there are obvious abnormalities by observing the appearance of the transformer: such as whether the coil lead is broken, whether the insulating material has scorch marks, whether the fastening screw of the iron core is loose, whether the silicon steel sheet is rusted, and whether the winding coil is exposed Wait. (2) Test a transformer with a digital multimeter, open all secondary windings, put the multimeter in the AC block (500mA, in series into the primary winding). When the plug of the primary winding is inserted into the 220V AC mains supply, the multimeter indicates the no-load current value. This value shall not be greater than 10% - 20% of the full load current of the transformer. Generally, the normal no-load current of the power transformer of common electronic equipment should be about 100mA. If too much is exceeded, the transformer has a short-circuit fault. Low Voltage Electronic Transformer Troubleshooting Guide5.3 Repairing a Transformer(1) Understand the reasons for the problem. Generally, a transformer has failed due to some fault in the electrical circuit.(2) Check the replacement transformer. If the short circuit is caused by component failure, the new transformer may still burn out. If you replace the transformer, examine it to make sure that the incident will not occur again.(3) Check the condition of the external fuse. If the transformer has an internal fuse, there may not be a fuse on the power line. On the contrary, the device must be protected by a fuse mounted on the power circuit. Check whether the fuse is intact and replace the faulty fuse.(4) Check the secondary power consumption. Sometimes, this kind of consumption is very high, which leads to equipment failure. If the transformer has multiple ratings and the multimeter shows the value "OL" during the measurement, it may be a short circuit in the secondary winding.5.4 Malfunction of Factory Low Voltage Transformer(1) Abnormal sound in transformerThe abnormal sound inside the transformer may be caused by the following reasons:①Heavy overload causes buzzing sound inside the transformer; ② Due to poor internal contact or breakdown point, the transformer occurs crackle sound③ Some parts of the connection shaft and the core of the transformer are loose, which causes the silicon steel sheet to vibrate④ When there is a grounding or short-circuit fault in the power grid, a large current flows through the winding, which will produce strong noise⑤ The iron core, the winding discharges to the shell, or the core ground wire is disconnected. All these can make the transformer discharge sound. (2) The oil level of the transformer is too high or too lowUnder normal circumstances, the changes in oil temperature can cause a change in oil level. As the oil temperature changes, the oil level also changes accordingly. However, under abnormal conditions, abnormal oil levels can also be caused by faults such as oil seepage and water seepage and other accidents. Second, the change in oil temperature is related to load conditions, ambient temperature and other conditions. When the change of oil level is inconsistent with these elements, it may be a false oil level. (3) Transformer oil quality has deteriorated or oil temperature has suddenly increasedIn working condition, the main function of transformer oil is cooling and insulation. When running overheated for a long time or if water enters the casing and absorbs moisture, the oil quality will deteriorate. Through the oil mark, we can found  that the oil color is abnormally deepened or blackened. Through sampling and analysis, it can be detected that the oil contains carbon particles and moisture, the acid value increases, the flashpoint decreases, and the insulation strength decreases. This situation can easily lead to serious accidents. A sudden rise in oil temperature when the transformer is operating normally is often related to the overheating inside the transformer. The iron core catches fire, the internal screws are loose, the cooling device is faulty, the transformer is heavily overloaded, all may cause the oil temperature to rise suddenly. (4) Transformer on fireWhen the transformer is out of order and it is not handled in time, it may catch fire. When the transformer is on fire, the insulating oil burns and turns into gas, which makes the oil tank burst. The burning insulating oil sprays out of the transformer, which will cause equipment damage and property loss. The short circuit inside or outside the transformer wire, severe overload, a lightning strike may cause the transformer to catch fire.VI One Question Related to Low Voltage Transformer6.1 Question (Multiple choice questions)The winding of wire around a core which is connected to a source of energy is called the ______ coil.primarysecondarytertiary6.2 AnswerA、B  VII FAQ1. What are low voltage transformers?A low voltage transformer is at the heart of every landscape lighting system. It converts 120-volt current to a low voltage current (between 12-15 VAC). ... Magnetic transformers use two coils to reduce the voltage from 120 volts down to 12 volts. 2. What low voltage transformer do I need?Transformers generally range from 150- to 900-watt capacity. Matching the size of the transformer to the lighting design is important for the efficient operation and function of the system. House current, 120 volts, is reduced by a transformer to 12 to 20 volts, the current needed to operate low-voltage landscaping lights. 3. What are low voltage transformers used for?Low Voltage Transformers Low voltage transformers are power transformers that are used to change the voltage capacity of a low-voltage electrical transmission line. Typically, electronic low voltage transformers convert 120 volts into 12 volts or 24 volts. 4. How do you test a low voltage transformer?• Identify the transformer's terminals, using its label as a guide. • Turn a multimeter to its VAC function. • Test the transformer's input voltage with the multimeter, using the transformer's label as a terminal guide. • Test the transformer's output voltage with the multimeter. 5. How long do low voltage transformers last?20 to 25 years.They operate at about 90 to 95 percent efficiency and can run for a very long time, anywhere from 20 to 25 years. They also are much quieter, so you can place them close to the fixtures, rather than having to run wires a long way from the transformer to the fixture itself. 6. Can I plug a low voltage transformer into an extension cord?One warning though to be observed is to never use an extension cord between the transformer and the electrical outlet. Always plug the transformer directly into the power outlet. As you can see, low voltage outdoor lighting is not all that hard to install or maintain. 7. Can you hardwire a low voltage transformer?To hardwire a low voltage transformer, the main power should be turned off at the breaker panel before making any electrical connections. ... The polarity of these wires is not important; either wire on the output side of the transformer may be connected to either wire of the low voltage circuit. 8. Do you need a transformer for low voltage lighting?When operating low voltage lights, you need a transformer to convert your standard line voltage (120V or 277V) into low voltage (12V or 24V). This allows your lights to function properly. If you connect low voltage lights directly to line power, the higher voltage would cause them to burn out immediately. 9. How do you tell if a transformer is going bad?Symptoms of power quality issues include vibration, excessive buzzing or humming and overheating. Technicians should occasionally check the power of transformers that supply nonlinear loads, such as variable frequency drives (VFDs) or switching power supplies. 10. Can you replace a transformer with a light fitting?They will have a transformer either in the ceiling or light fitting. Some LED bulbs, like the Philips Master LED range, have in-built circuitry that can deal with most (but not all) transformers, so you don't have to change them. In other cases, you need to replace the transformer with an LED driver.