The Kynix Components

4N25 is a General Purpose Optocoupler. This bolg covers 4N25 Optocoupler pinout, datasheet, equivalent, features and other information on how to use and where to use this device.Catalog4N25 Pinout4N25 Applications4N25 Features4N25 Advantage4N25 Equivalent4N25 Package4N25 Parameters4N25 Documents4N25 Product ComplianceWhy to Use 4N25 optocoupler4N25 CircuitHow to Safely Long Run 4N25 in a CircuitHow to Use 4N25 OptocouplerWhere to Use 4N25 Optocoupler4N25 Popularity by Region4N25 Market Price Analysis4N25 ManufacturerComponent DatasheetFAQOrdering & Quantity4N25 CAD Model4N25 Symbol 4N25 Footprint4N25 3D4N25 PinoutPin NO.Pin NamePin Description1AnodeIR LED Anode/ Positive Pin2CathodeIR LED Cathode/ Negative Pin3NCNot Connected Pin4EmitterBase Pin of the Photo Transistor5CollectorCollector Pin of the Photo Transistor6BaseEmitter Pin of the Photo Transistor4N25 ApplicationsThe 4N25 is widely used in many electronic applications because of its advanced features and characteristics. Following are some applications 4N25 optocoupler is used for.Solid State RelaysI/O InterfacingGeneral Purpose Switching CircuitReed Relay DrivingAC mains detectionLogic Ground IsolationTelephone ring detectionSwitch mode power supply feedbackMotor drive and controlCommunication and networkingPower management4N25 FeaturesIR LED Forward Voltage for turning ON: 1.25V-1.5V (Typically 1.3V, 1.5V being absolute maximum forward voltage)IR LED Forward Current during ON: 10mA - 60mA (Typically 10mA, 60mA being absolute maximum forward current)IR LED Reverse Voltage Maximum: 5VIR LED Reverse Current Maximum: 100uAMaximum voltage across COLLECTOR and EMITTER of TRANSISTOR: 70VMaximum current allowed trough TRANSISTOR COLLECTOR: 100mATypical Rise Time: 2usTypical Fall Time: 2usNo additional power needed to be applied for chip for making it work.4N25 Advantage4N25 General Purpose Optocoupler4N25 is also a widely used optocoupler / optoisolator / photocoupler, It is a general purpose optocoupler like PC817, MOC3021 etc. It is manufactured in 6 pin dip package and SMD package. The device consists of one IR LED and one phototransistor / Detector which detects the light comes from the IR LED. 4N25 also having the base pin of the detector transistor connected with the pin6 of the body, hence the user can control transistor by two inputs one from the IR LED light which is connected to pin1 and pin2 and other from controlling the transistor with its base.The phototransistor can handle max 30V and max150mA across it collector-emitter. Moreover the collector-emitter saturation voltage is from 0.15 to 0.5 which is ideal to use in applications where voltage saturation is required. The max forward current of the IR LED is 60 milliampere and the max power dissipation of the IR LED is 120 milliwatt. The pin3 is a NC pin that is also shown in the 4N25 pinout or pin diagram above “NC” means it is not connected with the internal circuitry of the device.4N25 Equivalent4N25 replacement and equivalent optocouplers are 4N26, 4N28, PC817, PC816, 4N27, 4N35, 4N36 & H11Ax series.4N25 PackagePackage Dimensions in millimetersPackage Marking4N25 ParametersBrandVishay SemiconductorsConfiguration1 ChannelCurrent Transfer Ratio50 %Height3.81 mmIf - Forward Current60 mAIsolation Voltage5000 VrmsLength8.7 mmManufacturerVishayMaximum Collector Current100 mAMaximum Collector Emitter Saturation Voltage0.5 VMaximum Collector Emitter Voltage70 VMaximum Operating Temperature+ 100 CMinimum Operating Temperature- 55 CMounting StyleThrough HoleNumber of Channels1 ChannelOutput TypeNPN PhototransistorPackage / CaseDIP-6PackagingTubePd - Power Dissipation150 mWProduct CategoryTransistor Output OptocouplersProduct TypeTransistor Output OptocouplersSeries4N2xSubcategoryOptocouplersUnit Weight0.012346 ozVf - Forward Voltage1.5 VVr - Reverse Voltage5 VWidth6.5 mm4N25 DocumentsCertificatesREACH Certificate (PDF)PCNProduct Change Notification (PDF)4N25 Product ComplianceUSHTS8541408000CAHTS8541400091CNHTS8541409000KRHTS8541409029MXHTS85414001TARIC8541409090ECCNEAR99Why to Use 4N25 optocouplerFor understanding the use of optocoupler consider:Case 1: where you want to isolate load circuit from control circuit. Say you want to control the speed of a small DC motor by using microcontroller PWM output. This setup is not feasible as microcontroller is sensitive device. So for isolating load circuit and protecting the controller from voltage fluctuations we use optocoupler.Case 2: Say you want to trigger a MOSFET circuit which is driving a high power load. The MOSFET trigger voltage typically is 12V. These voltages bursts (+12V) needed for MOSFET driver to control the high power load cannot be draw from controller. As controller puts out +3.3V or +5V bursts. In those cases using 4N25 optocoupler chip is ideal.Case 3: Consider we want to switch a 12V relay which is looping 220V AC fan according to RASPBERRY PI outputs. It is ideal to use 4N25 in this case, as 4N25 draws negligible amount of power considering a transistor or a MOSFET.4N25 Circuit4N25 Switching SchematicHow to Safely Long Run 4N25 in a CircuitTo get long term performance with this device it is suggested that the user should always stay below the absolute max ratings. The maximum load the device can handle is 150mA therefore do not connect load more than 150mA. Always use a suitable current limiting resistor with the IR LED. Always operate in temperature above -55 centigrade and below +100 centigrade and store in temperature above -55 centigrade and below +150 centigrade.How to Use 4N25 OptocouplerUsing 4N25 optocoupler is pretty straight forward; this optoisolator contains 6 pins as shown in the above 4N25 pinout diagram. The LED side of this or any other optoisolator is connected just like any other normal LED like Anode pin with the positive and cathode pin with the negative or ground. Now connected the Anode pin (Pin1) with the output you want to use the output should be positive and the cathode pin (Pin2) be should be connected with negative or ground of the same circuit. Now the other part of the device which is the phototransistor, the phototransistor have two base one is connected with the photo detector which detects the IR LED light and switches ON the transistor and the second one is connected with pin 6 which also switches ON the transistor when current is applied on the base. Hence the phototransistor can be operated like a general BJT transistor and also like a phototransistor or the user can also use the transistor in both ways for example one signal output is connected with the IR LED and the other signal output is connected with the base of the transistor.Where to Use 4N25 Optocoupler4N25 optocoupler can be used for variety of purposes and requirements in electronic circuits. For example it can be used in electronic applications where there is a chance of voltage surge or spikes which most of the time damage the electronic circuits and components due to which it can be used for the safety of the components. The photocoupler isolates one circuit from the other so you can use it easily when there is a requirement of isolation between two circuits. Apart from this it can also be used as voltage detector in AC and DC operated circuits, output of microcontroller to operate other devices and applications from microcontrollers, controlling relay, controlling MOSFET and other high power transistors, high voltage circuits, controlling AC and DC high voltages etc.4N25 Popularity by Region4N25 Market Price Analysis4N25 ManufacturerVishay Semiconductors includes the former Vishay Telefunken product lines, the former General Semiconductor product lines, the infrared component product lines acquired from Infineon Technologies, and selected product lines acquired from International Rectifier (excluding planar high-voltage MOSFETs).The Vishay Semiconductors product portfolio includes rectifiers, fast-recovery diodes, high-power diodes and thyristors, small-signal diodes, Zener and suppressor diodes, RF transistors, optoelectronics, power modules (a combination of power diodes, thyristors, MOSFETs, and IGBTs), and automotive modules and assemblies.Vishay is the world's number one manufacturer of rectifiers, glass diodes, and infrared components.Component Datasheet 4N25 DatasheetFAQWhat is a 4N25?4N25 is a General Purpose Optocoupler. What package is 4N25 manufactured in?6 pin dip package and SMD package How many IR LEDs does 4N25 consist of?One IR LED and one phototransistor / Detector

Product OverviewThe ALC892 is a high-performance multi-channel High Definition Audio Codec with Realtek proprietary lossless content protection technology that protects pre-recorded content while still allowing full-rate audio enjoyment from DVD audio, Blu-ray DVD, or HD DVD discs. CatalogALC892 FeaturesALC892 ApplicationsALC892 AlternateALC892 PinoutALC892 Filter ConnectionALC892 Mechanical DimensionsALC892 SpecificationALC892 DatasheetManufacturerUsing WarningsALC892 FAQ  Realtek Alc892 Audio N Gigabit Ethernet Solved - Hackintosh Big Sur 11.0.1 ALC892 FeaturesHardware FeaturesDACs with 95dB SNR (A-weighting), ADCs with 90dB SNR (A-weighting)Ten DAC channels support 16/20/24-bit PCM format for 7.1 channel sound playback, plus 2 channels of concurrent independent stereo sound output (multiple streaming) through the front panel outputTwo stereo ADCs support 16/20/24-bit PCM format, multiple stereo recordingAll DACs supports 44.1k/48k/96k/192kHz sample rateAll ADCs supports 44.1k/48k/96k/192kHz sample ratePrimary 16/20/24-bit SPDIF-OUT supports 32k/44.1k/48k/88.2k/96k/192kHz sample rateSecondary 16/20/24-bit SPDIF-OUT supports 32k/44.1k/48k/88.2k/96k/192kHz sample rate16/20/24-bit SPDIF-IN supports 44.1k/48k/96k/192kHz sample rate Software FeaturesMeets Microsoft WLP 3.x and future WLP audio requirementsWaveRT-based audio function driver for Windows Vista and Windows 7Direct Sound 3D™ compatibleI3DL2 compatible1+2 channel multi-streaming enables concurrent gaming/VoIPEmulation of 26 sound environments to enhance gaming experience ALC892 ApplicationsDACs with 97dB SNR (A-weighting), ADCs with 90dB SNR (A-weighting)Ten DAC channels support 16/20/24-bit PCM format for 7.1 channel sound playback, plus 2 channels of concurrent independent stereo sound output (multiple streaming) through the front panel outputTwo stereo ADCs support 16/20/24-bit PCM format, multiple stereo recording ALC892 AlternateALC892GR ALC892 Pinout ALC892 Pinout ALC892 Filter Connection Filter Connection ALC892 Mechanical Dimensions Filter Connection ALC892 SpecificationPart Life Cycle Code:ActiveRisk Rank:5.84Filter:YESJESD-30 Code:S-PQFP-G48Length:7 mmNumber of Functions:1Number of Terminals:48Operating Mode:SYNCHRONOUSOperating Temperature-Max:70 °CSupply Voltage-Nom:3.3 VTemperature Grade:COMMERCIAL ALC892 Datasheet ALC892 Datasheet ManufacturerRealtek Semiconductor Corp. is a Taiwan-based company principally engaged in the research, development, production and distribution of integrated circuits (ICs). The Company's products portfolio consists of communications network ICs, including Ethernet controllers, gateway controllers, network interface controller chips, switch controllers, wireless local area network (WLAN) chips and others; computer peripheral ICs, including personal computer (PC) audio compression/decompression modules (CODECs), consumer audio CODECs, card reader controllers and clock generator chipsets. Using WarningsNote: Please check their parameters and pin configuration before replacing them in your circuit. ALC892 FAQ① Are there any sound drivers for the Realtek ALC892?A complete list of available sound device drivers for Realtek ALC892. On this page, you will find all available drivers listed by release date for the Windows 10 64bit operating system. ② Is the ALC892 compatible with Intel chipsets?The ALC892 supports host audio from the Intel chipsets, and also from any other HDA compatible audio controller. ③ Can a ALC892 be used as a HDMI transmitter?The ALC892 also features secondary SPDIF-OUT output and converter to transport digital audio output to a High Definition Media Interface (HDMI) transmitter. The ALC892 supports host audio from the Intel chipsets, and also from any other HDA compatible audio controller. ④ What is the characteristic of ALC892? High-performance multi-channel 

As we have introduced in the last blog, UC3842 is a fixed frequency current-mode PWM  controller. This IC is specially designed for Off-Line and DC to DC converter applications with minimum external components. In the blog today, we'll have a further discussion about the application of  UC3842  in the boost conversion circuit.CatalogBoost Conversion Circuit OverviewI. Circuit Model of Boost Converter in DCM Mode1.1 Mathematical Model of DCM Working Mode1.2 Working Conditions of DCM ModeII. DCM Circuit Design Based on UC38422.1 DCM Circuit Design Based on Adder2.2 UC3842 Working PrincipleIII. Simulation and Analysis of DCM Mode CircuitIV. ConclusionV FAQBoost Conversion Circuit OverviewBoost converter s can reduce the output current and the capacitance and volume of the output filter capacitor under a certain output power, and are widely used in switching power supplies and electronic ballasts. Commonly used control methods are voltage feedback control and current feedback control,  Current feedback control can force the inductor current to track the reference current signal, which has the advantage of a fast response.  When working in continuous current mode (CCM), the Boost converter needs to introduce multiple feedback methods. When working in discontinuous current mode (DCM), the converter automatically shapes the input current, has a natural zero-current turn-on characteristic, requires a small inductance value, simple control, and is suitable for low-power applications. At present, there is much research on the  CCM  mode of Boost conversion circuit, and many circuit models have been established, and gratifying research results have been obtained; the research on DCM mode is mainly DC/DC circuit, and the research on DCM mode in AC/DC circuit Very little. Based on the requirements of a low-power switching power supply with low cost and high-cost performance, this paper uses the universal UC3842  chip to design a Boost conversion circuit, analyzes the working characteristics and design points of the DCM mode, and simulates the rationality of the designed circuit verification. I. Circuit Model of Boost Converter in DCM Mode1.1 Mathematical Model of DCM Working ModeThe Boost conversion circuit structure is shown in Figure 1(a). In the CCM mode, the switching tube M and the diode VD5 are turned on in a complementary manner; when the inductance is small or the switching cycle is relatively long, before the start of the next cycle, the diode VD5 and M are all turned off, and the Boost conversion circuit works in DCM mode at this time. The corresponding waveform between the inductor current and the pulse width modulator (PWM) output pulse is shown in Figure 1(b).Figure 1 Boost conversion circuit and DCM mode waveform diagram In the K-th switching modulation cycle, the on-off states of the switch tube M and the diode VD5 satisfy the relationship:T is the high-frequency modulation period of PWM; KT is the K-th high-frequency modulation period of PWM; D1T is the rise time of the inductor current in the high-frequency modulation period; D2T is the fall time of the inductor current in the high-frequency modulation period; D3T is the time when the inductor current is zero in the high-frequency modulation period. When the Boost circuit works in DCM mode, as the switch tube M and the diode VD5 turn on and off, the state of the system can use a differential equation:In the formula, KT+D1T+D2T+D3T=(K+1)T; iL(t) is the instantaneous value of the inductor current; υin(t) is the instantaneous value of the input voltage on the grid side; υo(t) is Boost The instantaneous value of the converter output voltage. 1.2 Working Conditions of DCM ModeIt can be seen from Figure 1 that the inductor current of the Boost converter in DCM mode increases linearly from zero. In each modulation cycle, there is:When the circuit output filter capacitor is large, the output voltage ripple can be ignored compared with the output voltage amplitude, and the output voltage υo(t) can be regarded as a constant υo. In a dual-loop control system, the current-loop reference current Iref is determined by the output of the voltage outer loop, and there is:In the formula, υr(t) is the instantaneous value of the reference voltage provided by the voltage loop for the current loop; Rs is the sampling resistance for detecting the current. When the inductor current follows the sinusoidal input voltage waveform, the power factor is close to 1, and the available duty cycle D1 can be expressed as: In the formula, Vref is the peak value of υr(t) in the power frequency period; Vin is the peak value of υin(t) in the power frequency period. The same principle can be obtained, in each modulation period, the expression of the duty cycle D2 is:When the Boost converter works in the critical mode, the duty cycle satisfies the relationship D1+D2=1. From this, it can be deduced that the critical condition for the Boost circuit to enter the CCM mode from DCM is:When L<LCRM, Boost circuit works in DCM mode; When L>LCRM, Boost circuit works in CCM mode. At this point, the following conclusions can be drawn: (1) In the DCM mode, the on-time D1T of the switch tube M is a fixed value, which does not change with the size of the inductor current. (2) When the switch is turned off, the time D2T when the inductor current drops to 0 changes with the output voltage and input voltage. The greater the input voltage, the greater the D2T, the greater the output voltage, and the smaller the D2T. II. DCM Circuit Design Based on UC38422.1 DCM Circuit Design Based on AdderThe DCM-type Boost circuit includes two control loops, namely a voltage loop and a current loop. Its function is to eliminate the grid current spikes, so that the input current becomes a sinusoidal shape and is in phase with the input voltage. For a single switching cycle, the current in each switching cycle is required to be proportional to the input voltage.  If for some reason the output voltage increases or the output current increases, the pulse width modulator will change the pulse width of the drive signal, that is, the duty cycle D, so that the average voltage or peak current after the chopping will decrease. So as to achieve the purpose of power factor correction. The DCM circuit schematic diagram based on the adder is shown in Figure 2.Figure 2 DCM circuit schematic diagram based on adder The voltage outer loop uses an adder to replace the multiplier circuit. The feedback voltage on the grid side is used to ensure that the current signal is a sinusoidal signal, and the output feedback voltage is used to ensure that the output voltage is a constant value. The two are synthesized by the adder U2. The output signal is sent to the error amplifier in the UC3842 current loop, compared with a given reference voltage, and the comparison result is sent to the current measurement comparator. The peak current signal L(t) of the inductor in the main circuit is sent to the current measuring comparator at the same time, the comparison result of the two is sent to the R input of the RS latch in the PWM.  The clock signal output by the internal oscillating circuit is sent to the S input end of the RS latch in the PWM, which works together to control the opening and closing of the switch tube M1. 2.2 UC3842 Working PrincipleUC3842 is a high-performance single-ended output current-type PWM controller. The current control loop is composed of a PWM latch, a current detection comparator, an error amplifier, and a sawtooth oscillation circuit. Its internal structure is shown in Figure 3.Figure 3 UC3842 working principle diagram UC3842 can generate a drive signal with a fixed frequency and adjustable pulse width. External components RT and CT can be used to set the oscillation frequency and precisely control the duty cycle. The output voltage of UC3842 can be adjusted by controlling the on-off state of the switch tube to achieve the purpose of voltage stabilization. The UC3842 has a good voltage regulation rate, good frequency response characteristics, large stability amplitude, over-current limit, overvoltage protection, and under-voltage lockout function. And it has fewer external pins, small size, is an economical PWM driver control chip. III. Simulation and Analysis of DCM Mode CircuitIn order to verify the correctness of the deduced critical conditions and the designed circuit, the designed circuit was simulated and verified by OrCAD10.5 software. When the power input is power frequency alternating current and its circuit parameters are υin=311.13sin(ωt), υo=385V, RL=1482Q, L=400μH, the Boost converter works in DCM mode, and its output voltage and inductor current waveforms are as follows Shown in Figure 4.Figure 4 Boost converter output voltage and inductor current waveform The waveform of the duty cycle at different times is shown in Figure 5.Figure 5 The size of the duty cycle D1T at different times If the inductance value increases and exceeds the critical value LCRM, the inductor current will change from DCM mode to CCM mode. When the inductance value L=1.2mH, Vo=508V, the waveform is shown in Figure 6.Figure 6 Inductor current waveform when L=1.2mH The waveform of the duty cycle D1T in the DCM stage is shown in Figure 7Figure 7 The duty cycle of the DCWI phase when the inductance exceeds the critical value It can be seen from the simulation results that in the DCM mode, the on-time of the switch is a fixed value. When the inductance L is greater than the critical value, there will be a transition from DCM to CCM. The CCM mode appears near the peak of the power frequency current. IV. ConclusionThis text summarizes the Boost conversion circuit design scheme based on the UC3842 chip. By analyzing the circuit of Boost converter in DCM mode, the circuit model of Boost converter in DCM mode is established, and the duty cycle change rule in this mode and the critical conditions for entering CCM mode from DCM mode are studied.  Using the universal PWM  modulator UC3842 chip, a Boost conversion circuit based on the principle of addition is designed, and the correctness of the conclusions obtained is verified by simulation software. The circuit simulation results show that the designed DCM circuit can meet the requirement of the inductor current to follow the voltage waveform completely and achieve the purpose of improving the power factor. This research provides design ideas for the development of low-cost low-power switching power supplies.V FAQWhat are two common control methods used by Boost converters?Voltage feedback control and current feedback control. In what mode does the Boost converter need to introduce multiple feedback methods? Continuous current mode What type of circuit is the research on DCM mode?DC/DC circuit What are two control loops in the DCM-type Boost circuit?Voltage loop and a current loop What is the purpose of the DCM-type Boost circuit?Power factor correction What is the current control loop composed of?A sawtooth oscillation circuit What is the UC3842?PWM driver control chip How can the output voltage of UC3842 be adjusted?By controlling the on-off state of the switch tube

The MPF102 JFET is a popular N-Channel JFET that is commonly used in low-power amplifier circuits. The JFET is no longer in production and it might be difficult to find. Therefore, they are not recommended for new designs.Initial Experiments with the MPF102 JFETCatalogMPF102 General DescriptionMPF102 PinoutMPF102 FeaturesMPF102 EquivalentsHow to Use MPF102 JFETMPF102 ApplicationsMPF102 PackageComponent DatasheetFAQMPF102 General DescriptionThe MPF102 is a JFET that has been used in many amplification circuits due to its low price. At present, JFET is no longer in production, but until the demand for it has produced many clones on the market. The closest equivalent to the NTE457 is the J113 FET. Clone FETs available on the market do not appear to follow the datasheet strictly. So be careful which one is used in your designs. Provided you have the right FET, it can be used in the pre-amp circuit to achieve a gain of +12dB or higher. If you can't find a supplier, consider upgrading to NTE457 that its slightly pricey but availability will not be a problem.MPF102 Pinout Pin NumberPin NameDescription1DrainCurrent flows in through Drain pin2SourceControls the biasing of FET3GateCurrent flows out through Drain, normally connected to ground. MPF102 FeaturesGeneral Purpose N-Channel Junction Field Effect TransistorDrain-Source voltage (VDS) is 25 VMaximum Drain current: 20mADrain-Gate voltage (VDG) is 25VGate-Source Voltage (VGS) is -7.5VGate Current (IG) is 10mAAvailable in To-92 PackageMPF102 EquivalentsNTE457, J113How to Use MPF102 JFETA JEFT is considered to be in the default state that even if a single gate is not provided (0V) the JFET will allow the current to flow from Drain to Source. To top the JEFT, a negative gate voltage must be applied to the gate pin, for the MPF102 it should normally be-7.5V.MPF102 CircuitsThe above two images should show how to configure a load (LED) using a JFET like MPF102. When the gate pin is grounded, the JFET enables the current to flow from the drain to the source and the LED is switched on. When using-7.5V on the gate pin, the JFET blocks the current flow between the Drain and Source pins and turns the LED off.MPF102 ApplicationsAmplifier circuitsPre-Amp applicationsAudio noise cancelation MPF102 PackageIf you are designing a PCB or Perf board with this component, the following image from the MPF102 Datasheet will be useful to know its package type and dimensions.Component DatasheetMPF102 JFET DatasheetFAQWhy is the MPF102 JFET not in production?They are not recommended for new designs What is the closest equivalent to the NTE457?J113 FET What must be applied to the gate pin to top the JEFT?A negative gate voltage What will allow the current to flow from Drain to Source?The JFET

PC817 is a photocoupler. PC817 consists of a diode emitting LED and a phototransistor. They're optically coupled together. The electrical signal is transmitted optically between the input and the output side without any physical connection between the two sides. The IR circuit can be designed by hand, but we have a fully pre-designed and small built-in IC circuit known as the PC817 Optocoupler. The PC817 Optocoupler is small and comes in multiple packages. This video is about how to test photocoupler PC817.CatalogPC817 PinoutPC817 FeaturesPC817 EquivalentWhere to Use PC817 ICHow to Use PC817 IC PC817 ApplicationsPC817 PackageComponent DatasheetFAQPC817 PinoutPC817PC817 Pinout Pin NameDescriptionAnodeAnode pin of the IR LED. Connected to logic inputCathodeCathode pin of the IR LED. Connected to groundEmitterEmitter pin of transistor. Connected to GroundCollectorCollector pin of the Transistor. Provides logical outputPC817 FeaturesInput Diode Forward Voltage: 1.25VCollector-Emitter Voltage: 80V (max)Collector Current: 50mA (max)Cut-off frequency: 80 kHzRise Time: 18usFall Time: 18usAvailable as 4-pin DIP through hole and also as SMT package.PC817 EquivalentTLP321Alternatives Opto-couplers: MOC3021 (Zero Cross TRIAC) , MOC3041 (Non-Zero Cross TRIAC), FOD3180 (High-Speed MOSFET), MCT2E, 4N25Where to Use PC817 ICPC817 Photocoupler has a transistor which is controlled based on light (photon). So this IC basically has an IR (infrared) LED and a phototransistor inside it. When the IR LED is powered, the light from it falls on the transistor and it conducts. The arrangement and pinouts of the IR LED and the photo-transistor is shown above. This IC is used to provide electrical insulation between two circuits, one part of the circuit is connected to the IR LED and the other part to the Photo Transistor. The digital signal to the IR LED will be reflected on the transistor, but there will be no hard electrical connection between the two. This comes in handy when you're trying to isolate a noisy signal from your digital electronics, so if you're looking for an IC to provide optical insulation in your circuit design, this IC might be the right choice for you.How to Use PC817 ICUsing the PC817 IC is pretty straight forward, we just need to connect the a node pin of the IR LED (pin 1) to the logic input to be isolated and the cathode (pin 2) of the IR to the ground. Then pull the collector pin out of the transistor using the resistor (here I used 1K) and connect the collector pin to the output of your desired logic circuit. The emitter (pin 4) has been grounded. Note: The ground line of the IR LED (pin 2) and the ground line of the transistor (pin 4) are not connected together. This is where isolation is taking place.PC817 Circuit Diagram Now, when the Logic input is low, the IR LED will not be running and therefore the transistor will also be off-state. As a result, the Logic output will remain high, this high voltage can be set anywhere up to-30V (Collector-Emitter Voltage) where I used +5V. The pull-up resistor 1K acts as a load resistor. But when the Logic input is high, this high voltage should be at least 1.25V (Diode Forward voltage) of the IR LED, so that the phototransistor is also switched on. This will shorten the collector and emitter, and therefore the Logic Output voltage will become zero. This way, the logic input will be reflected in the logic output and still provide and insulate between the two. The complete working of the GIF file above can also be understood. Another important parameter to consider while using the Optocoupler is the time of increase (tr) and fall time (tf). The output will not be high as soon as the input logic is low and vice versa. The waveform below shows the time taken for the output to transit from one state to another. The increase time (TPDHL) and fall time (TPDLH) for PC817 is 18us. PC817 ApplicationsElectrical Isolation circuitsMicrocontroller I/O switching circuitsSignal isolationNoise coupling circuitsIsolation digital from analog circuitsAc/DC Power controlPC817 PackageComponent DatasheetPC817 DatasheetFAQWhat does PC817 consist of?Diode emitting LED and a phototransistor How are the LED and phototransistor connected to the PC817?Optically coupled together. What is the use of PC817?Embedded project for isolation purposes. What is the output voltage of optocoupler?At potentials up to 5,000 volts, the optocoupler is utilized to communicate analog or digital information between circuits while retaining electrical isolation. When the potential difference between two circuits exceeds 5,000 volts, an optoisolator is utilized to transmit analog or digital data.

CatalogDHT22 DescriptionDHT22 Related Video InstructionDHT22 CAD ModelsDHT22 DimensionsDHT22 Electrical Connection DiagramDHT22 Features & ApplicationsDHT22 Attentions of ApplicationDHT22 DatasheetDHT22 Technical SpecificationDHT22 ManufacturerUsing WarningDHT22 FAQ DHT22 DescriptionDHT22 output calibrated digital signal. It utilizes exclusive digital-signal-collecting-technique and humidity sensing technology, assuring its reliability and stability.Its sensing elements is connected with 8-bit single-chip computer. Every sensor of this model is temperature compensated and calibrated in accurate calibration chamber and the calibration-coefficient is saved in type of programme in OTP memory, when the sensor is detecting, it will cite coefficient from memory. Small size & low consumption & long transmission distance (20m) enable DHT22 to be suited in all kinds of harsh application occasions. Single-row packaged with four pins, making the connection very convenient. DHT22 Related Video InstructionVideo: DHT22 with Arduino - Humidity and Temperature Sensor with Touch Screen LCDDHT22 Video Description:How to get the DHT22 or DHT11 temperature and humidity sensor working with Arduino using Adafruit libraries.Starting with a basic serial monitor interface to show how to get the sensor working, a 16x2 LCD is added, then a 3.5 inch touch screen display with on-screen touch buttons. DHT22 CAD Models Figure: PCB Symbol  Figure: Footprint  Figure: 3D Model DHT22 Dimensions Figure:s Dimensions DHT22 Electrical Connection Diagram Figure: Electrical Connection Diagram DHT22 Features & Applications* Full range temperature compensated* Relative humidity and temperature measurement* Calibrated digital signal* Outstanding long-term stability* Extra components not needed* Long transmission distance* Low power consumption*4 pins packaged and fully interchangeable DHT22 Attentions of Application(1) Operating and storage conditions We don't recommend the applying RH -range beyond the range stated in this specification. The DHT22 sensor can recover after working in non-normal operating condition to calibrated status, but will accelerate sensors' aging. (2) Attentions to chemical materials Vapor from chemical materials may interfere DHT22's sensitive-elements and debase DHT22's sensitivity. (3) Disposal when (1) & (2) happens Step one: Keep the DHT22 sensor at condition of Temperature 50~60Celsius, humidity <10%RH for 2 hours; Step two: After step one, keep the DHT22 sensor at condition of Temperature 20~30Celsius, humidity >70%RH for 5 hours. (4) Attention to temperature's affection Relative humidity strongly depend on temperature.  that is why we use temperature compensation technology to ensure accurate measurement of RH. But it's still be much better to keep the sensor at same temperature when sensing. DHT22 should be mounted at the place as far as possible from parts that may cause change to temperature,   (5) Attentions to light Long time exposure to strong light and ultraviolet may debase DHT22's performance. (6) Attentions to connection wires The connection wires' quality will effect communication's quality and distance, high quality shielding-wire is recommended. (7) Other attentions * Welding temperature should be bellow 260Celsius. * Avoid using the sensor under dew condition. * Don't use this product in safety or emergency stop devices or any other occasion that failure of DHT22 may cause personal injury DHT22 DatasheetYou can download the datasheet of DHT22 from the link given below.DHT22-Datasheet DHT22 Technical SpecificationModelDHT22Power supply3.3-6V DCOutput signaldigital signal via single-busSensing elementPolymer capacitorOperating rangehumidity 0-100%RH;temperature -40~80CelsiusAccuracyhumidity +-2%RH(Max +-5%RH); temperature <+-0.5CelsiusResolution or sensitivityhumidity 0.1%RH;temperature 0.1CelsiusRepeatabilityhumidity +-1%RH;temperature +-0.2CelsiusHumidity hysteresis+-0.3%RHLong-term Stability+-0.5%RH/yearSensing periodAverage: 2sInterchangeabilityfully interchangeableDimensionssmall size 14*18*5.5mm;big size 22*28*5mm DHT22 ManufacturerAs a leading MEMS sensor designer and manufacturer, Aosong Electronic Co., LTD., was founded in 2003 and located in Guangzhou，China., focus on sensor chips design, wafer production, sensor module and system solutions(with the registered trademark “ASAIR”). Using WarningNote: Please check their parameters and pin configuration before replacing them in your circuit. DHT22 FAQWhat is the long transmission distance of DHT22?20m. What can the DHT22 sensor recover after working in non-normal operating condition?Calibrated status. How many pins are packaged and interchangeable?4 pins. What is DHT22 temperature and humidity sensor?The DHT22 is a basic, low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin (no analog input pins needed). It's fairly simple to use, but requires careful timing to grab data. Is DHT22 waterproof?The box is waterproof, only open at the bottom, so the sensors do not get wet.  How does a DHT22 work?The DHT22 is a basic, low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and spits out a digital signal on the data pin (no analog input pins needed). It's fairly simple to use but requires careful timing to grab data. What is the difference between DHT11 and DHT22?There are two specification where the DHT11 is better than the DHT22. That's the sampling rate which for the DHT11 is 1Hz or one reading every second, while the DHT22 sampling rate is 0, 5Hz or one reading every two seconds and also the DHT11 has smaller body size.