The Kynix Components

CJMCU-2551 is a fault-tolerant, high-speed CAN devices tjat can be used as CAN protocol controller and the physical bus interface. MCP2551 provides differential receive capability to the CAN protocol controller, which is fully in line with ISO-11898 standards, including energy 24V requirements.CatalogProduct OverviewMCP2551 PinoutMCP2551 ApplicationsMCP2551 Product FeaturesParametricsCAD ModelSpecificationsAlternatives for MCP2551-E/PHow to Build a CAN Transceiver Circuit with an MCP2551 Chip?MCP2551 Datasheet FAQ Product OverviewThe MCP2551-E/P is a high speed CAN (Controller Area Network) transceiver in 8 pin DIP package. This CAN fault tolerant device serves as the interface between CAN protocol controller and physical bus. The MCP2551 provides differential transmit and receive capability for CAN protocol controller and is fully compatible with ISO-11898 standard including 24V requirements. It will operate at speed of up to 1Mb/s. Typically each node in CAN system must have device to convert digital signals generated by CAN controller to signals suitable for transmission over the bus cabling (differential output). It also provides buffer between CAN controller and high voltage spikes that can be generated on CAN bus by outside sources (EMI, ESD, electrical transients). The MCP2551 CAN outputs will drive a minimum load of 45ohm allowing a maximum of 112 nodes to be connected. MCP2551 Pinout MCP2515 Pinout  MCP2551 ApplicationsAutomotiveCAN Interfaces MCP2551 Product FeaturesSlope control inputSupports 1 Mb/s operationImplements ISO-11898 standard physical layer requirementsSuitable for 12V and 24V systemsExternally-controlled slope for reduced RFI emissionsPermanent dominant detectLow current standby operationHigh noise immunity due to differential bus implementation ParametricsClick on a property to perform a parametric search for other products with that property.Operating Voltage (V) 4.5 - 5.5Temp Range (°C) -40 - +125CAN FD NO  CAD ModelSymbol footprint SpecificationsSpecifications Product AttributeAttribute ValueManufacturer:MicrochipProduct Category:CAN Interface ICRoHS:DetailsMounting Style:SMD/SMTPackage / Case:SOIC-8Series:MCP2551Type:CAN ControllerData Rate:1 Mb/sSupply Voltage - Max:5.5 VSupply Voltage - Min:4.5 VMinimum Operating Temperature:- 40 CMaximum Operating Temperature:+ 85 CPackaging:TubeProduct:CAN ControllersBrand:Microchip TechnologyMoisture Sensitive:YesNumber of Transceivers:1Operating Supply Voltage:5 VProduct Type:CAN Interface ICFactory Pack Quantity:100Subcategory:Interface ICsUnit Weight:0.002011 oz Alternatives for MCP2551-E/PManufacturer Part NumberNewark Part No.Manufacturer / DescriptionMCP2551-E/P58M8896MICROCHIPCAN Bus, Transceiver, CAN, Serial, 1, 1, 4.5 V, 5.5 V, DIP RoHS Compliant: YesMCP2551-I/P61K2947MICROCHIPCAN Bus, Transceiver, CAN, Serial, 1, 1, 4.5 V, 5.5 V, DIP RoHS Compliant: Yes How to Build a CAN Transceiver Circuit with an MCP2551 Chip? What is CAN bus ?The CAN bus is used in many applications, the most common being in automobiles. Many cars are equipped with a CAN bus and exchange messages through this bus.The MCP2551 is an 8-pin chip. The pinout for the chip is shown on pinout part. The breadboard of the circuit above is shown below. breadboard of the circuit  Components NeededMCP2551 CAN Transceiver ChipMicrocontroller or CAN Controller10KΩ resistor   MCP2551 CAN Transceiver CircuitThe circuit to build a CAN transceiver circuit using an MCP2551 chip is shown below.   build a CAN transceiver circuit Step1:  To power on the MCP2551 CAN transceiver chip, we connect VDD, pin 3, to 5V and we connect VSS, pin 2, to ground. The maximum voltage that the chip can receive is 7V, so 7V should not be exceeded. 5 volts supplies sufficient power for the MCP2551 to be able to operate. Step2:  The CAN-compatible device that you want to add to the CAN bus connects to the CANH and CANL pins. A CAN-compatible device has 2 terminals, a CANH and a CANL. You connect the CANH terminal of the device to the CANH terminal of the MCP2551 and the CANL terminal of the device to the CANL terminal of the chip. All devices that you want to connect to the CAN bus are connected to the CANH and CANL lines. Up to 112 nodes can be connected to the CAN bus. Step3: How it works is that the CANH and CANL lines are connected to the inputs of an internal comparator of the chip. These comparators measure the inputs and are able to give us the differential voltage output of the 2 signals. If the differential output is 0V, then the signal is said to be dominant. If the differential voltage is greater than 1V, then the signal is said to be recessive. Step4: The output of this signal, the differential signal, is output through the Rx pin, pin 4. This differential voltage is then transmitted either to the CAN controller or microcontroller for analysis. Step5: After the signal is analyzed by the microcontroller/CAN controller, it is then sent out from the Tx pin to the MCP2551 transceiver chip. So the Rx pin outputs the differential voltage to the microcontroller and the microcontroller outputs the analyzed signal through the Tx pin back to the MCP2551. This is why the chip is a transceiver. It sends out and receives data. Step6: To reduce EMI emission in the circuit, we connect the RS pin, pin 8, to a resistor connected to ground. A resistor of about 10KΩ suffices well. This prevents further EMI. And this is all that is required for connecting the hardware of a CAN transceiver chip. Step7: Programming the chip, on the other hand, is a completely different story and is much harder. These is because there are many components of the code to understand. There are identifier bits, error bits, understanding of priority, different formats, and more to deal with. Step8: Programming the chip requires a lot of in-depth knowledge about what exactly occurs during the entire receive/transmit process. You must also be able to decode the entire message for data transmission, which requires a good deal of knowledge. Step9: Again, CAN bus communication is a standard today. If you know the schematic diagram of the electronics housed in a car, you can access the data on this CAN bus system using a CAN transceiver chip and connect it to a micrcontroller to get data from electrical subunits of the car to a microcontroller for processing. This can allow you to tap into the data and perform whatever actions you need based on it. MCP2551 DatasheetMCP2551 Datasheet  FAQCAN SPI MCP2515 Arduino?MCP2515 Module has a CAN controller MCP2515 which is high speed CAN transceiver. The connection between MCP2515 and MCU is through SPI. So, it is easy to interface with any microcontroller having SPI interface. For beginners who want to learn CAN Bus, this module will act as a good start. CAN bus shield V2 adopts MCP2515 and MCP2551? The CAN-BUS Shield V2 still uses MCP2515 as CAN-BUS controller and MCP2551 as CAN transceiver. ... OBD-II or CAN standard pinout can be selected by switching jumpers on the DB9 interface, the default pinout is OBD-II. Added a TF card slot for data storage, and the CS pin can be either set to D4 or D5. How do CAN bus system work?Devices on a CAN bus are called “nodes.” Each node consists of a CPU, CAN controller, and a transceiver, which adapts the signal levels of both data sent and received by the node. All nodes can send and receive data, but not at the same time. Nodes cannot send data directly to each other.

Introduction74LS138 is a 3-line to 8-line decoder / demultiplexer. The chip is designed to be used in high-performance memory-decoding or data-routing applications, requiring very short propagation delay times. In high performance memory systems these decoders can be used to minimize the effects of system decoding. The three enable pins of chip (in which Two active-low and one active-high) reduce the need for external gates or inverters when expanding.CatalogIntroductionI Full Adder CircuitII Responder CircuitIII Logic FunctionIV Full Subtractor CircuitV Three-input Majority VotingFAQOrdering & QuantityI Full Adder Circuit The full adder has 3 input terminals: An, Bn, Cn-1; 2 output terminals: Sn, Cn. The 74LS138 3-line to 8-line decoder has 3 data input terminals: A, B, C; 3 enable terminals and 8 output terminals. Here, the 3 data input terminals of the 3-line to 8-line decoder can be regarded as the 3 input terminals of the full adder. That is, the inputs A, B, and C of the 3-line to 8-line decoder correspond to the inputs An, Bn, and Cn-1 of the full adder respectively. Set the 3 enable terminals of the 3-line to 8-line decoder to the effective level to maintain normal operation. The key point here is to deal with the relationship between the 8 output terminals of the 3-line to 8-line decoder and the 2 outputs of the full adder.Use the output OUT (1, 2, 4, 7) of the 3-line to 8-line decoder as a 4-input or gate input, and the gate output as the sum of the adder. Use the output OUT ( 3, 5, 6, 7) of the 3-line to 8-line decoder as a 4-input or gate input, the gate output is used as the carry output of the adder. When the input of the adder is: a=1, b=0, ci=1, the input of the corresponding 3-line to 8-line decoder is A=1, B=0, C=1. The output of the decoder is out (5) = 1 and the rest is 0. According to the connection relationship designed above, S = 0, CO = 1, which satisfies the function of full adder.Figure 1. Full Adder CircuitII Responder CircuitFigure 2. Responder CircuitIII Logic FunctionF = ABC + A‘BC + AB’C= 111 + 110 + 101= Y7 + Y6 + Y5According to the rule of 74LS138, A is the low bit (LSB) and D is the high bit (MSB). The 74LS138 decoding output is low level effective. With 74LS10 NAND gate, the actual logic is input low level effective or gate.Figure 3. Circuit of Logic FunctionIV Full Subtractor CircuitFigure 4. Full Subtractor CircuitV Three-input Majority VotingThe device consists of a 3-line to 8-line decoder (74LS138) and two 4-input NAND gates (74LS20). There are three buttons for user. Press the button to agree, not to press means to reject. When no one presses the button, or when only one person presses the button, for example, S1 is pressed, but S2 and S0 are not pressed. The red light is on, the green light is off, and the buzzer is silent, indicating veto. When two or more people press the button, for example, if S1 and S2 are pressed, the red light will be off, the green light will be on, and the buzzer will sound to indicate a pass. Use 74LS138 decoder and four-input NAND gate 74LS20 to realize this logic function.Figure 5. Circuit of Three-input Majority VotingFAQWhat type of applications is 74LS138 designed to be used?High-performance memory-decoding or data-routing applicationsHow many pins does 74LS138 reduce the need for external gates or inverters when expanding? Three enable pinsWhat is the difference between 74hc138 and 74LS138?Both have the same function. 74HC138 is made of high-speed CMOS process, with low power consumption, high output, low level and wide range.74LS138 adopts the early bipolar process, and its driving capability is relatively larger.What is the functional difference between 74ls138 decoder and 74ls148？74ls138 is a 3-8 wire decoder/multiplexer, 74ls148 is an 8-3 wire octal priority encoder.One is decoding and the other is encoding. Opposite effectWhat's the difference between 74LS138D and 74LS138N？Those two are the same chip, D is SOP package, N is DIP package.What are the output characteristics of 74LS138 decoder？Under the premise that the enable terminals S1 (active high), S2 (active low), and S3 (active low) are valid at the same time, only one output terminal is low at a time (the rest are high);If the enable terminal is invalid, the output is all high level.What do the letters and numbers in 74ls138 stand for？74ls138 is a 3-8-line decoder. The number 74 represents the 74 series of the 54/74 series, and the 74 series has an operating temperature of 0 degrees to 70 degrees. LS is a series, representing the low-power Schottky series. 138 is the variety code.What’s the working principle of 74ls138?74LS138 working principle① When one strobe terminal (E1) is high level, and the other two strobe terminals (E2) and (E3) are low level, at the output terminals corresponding to Y0 to Y7, the binary code of address terminals (A0, A1, A2)  can be decoded at low level. For example: when A2A1A0=110, the Y6 output terminal outputs a low-level signal.②Using E1, E2 and E3, it can be cascaded to expand into a 24-line decoder; if an external inverter is connected, it can also be cascaded to expand into a 32-line decoder.③If one of the strobe terminals is used as a data input terminal, 74LS138 can also be used as a data distributor.④It can be used in 8086 decoding circuit to expand memory. 

IntroductionMicrocontroller unit, also known as a single-chip microcomputer, is a small computer on an integrated circuit (IC) chip, which appropriately reduce the frequency and specifications of the CPU, and integrates memory, timer, USB, A/D conversion,  UART,  PLC,  DMA, and even LCD driver circuits on a single chip. The MCU  of the embedded control system usually needs a stable working voltage.However, designers are used to using linear voltage regulators (such as 78xx series three-terminal voltage regulator) to convert high DC voltage into working voltage required by MCU. The linear adjustment mode of the linear regulated power supply will cause large "heat loss", and its working efficiency is only 30% - 50%.The switching power supply regulator works in a completely on or off mode. Therefore, either the high current flows through the switch with low conduction voltage, or it is completely cut off without current flow. Therefore, the power consumption of the switching power supply is very low, and its average working efficiency can reach 70% - 90%. Under the same voltage drop, the switching power supply regulator has much less "heat loss" than the linear regulator. Therefore, the switching power supply can greatly reduce the size of the heat sink and the area of the PCB board. Even in most cases, there is no need to install a heat sink. It is helpful to reduce the harmful impact on the MCU  working environment.This article introduces the design scheme of using the LM2576 series switching power supply to replace the linear power supply as MCU power supply. It has two advantages. One is the high-frequency on-off characteristics of switch tubes. Another advantage is the use of a series filter inductor. They have a strong suppression effect on the high-frequency interference from the power supply. In addition, due to the reduction of the "heat loss" of the switching regulated power supply,  it is helpful to the ability of the AC voltage to resist drop interference if increased the input voltage of the regulated power supply.LM2576 series switching regulator integrated circuits have reliable working performance, high working efficiency, and strong output current driving ability, which provides a strong guarantee for the stable and reliable operation of MCU.CatalogIntroductionCatalogI Application DesignII Working ModeFAQOrdering & QuantityI Application DesignThe basic voltage stabilizing circuit composed of LM2576 only needs four peripheral devices, and its circuit is shown in Figure 1.Figure 1. voltage stabilizing circuitThe selection of inductance L1 depends on the output voltage, maximum input voltage, and maximum load current of  LM2576.  First, the electric voltage·microsecond constant (E·T) can be calculated according to the following formula:E·T=(Vin - Vout)×Vout/ Vin×1000/f (1)Vin is the maximum input voltage of LM2576, Vout is the output voltage of LM2576.  and f is the operating oscillation frequency value of LM2576  (52kHz).Generally, the input capacitance Cin in the circuit should be greater than or equal to 100 μF. when installing, it is required to be close to the input pin of lm2576  as far as possible, and its withstand voltage value should match the maximum input voltage value.The value of the output capacitor Cout (unit μF) should be calculated according to the following formula:C≥13300 Vin/ Vout×L (2)Vin is the maximum input voltage of LM2576; Vout is the output voltage of LM2576; L (unit μH) is the value of inductance L1. The withstand voltage value of capacitor C should be 1.5 ~ 2 times of rated output voltage. For 5V voltage output, it is recommended to use a capacitor with a voltage withstand value of 16V.The rated current of diode D1 should be 1.2 times the maximum load current. Considering the state of the short circuit and load, the rated current of the diode should be greater than the maximum current limit of LM2576. The reverse voltage of the diode should be greater than 1.25 times the maximum input voltage.The selection of Vin should consider the input voltage value of LM2576 corresponding to the lowest AC voltage drop (Vac-min) and the minimum input allowable voltage value Vmin of LM2576.  Therefore, Vin can be calculated according to the following formula:Vin≥(220Vmin/Vac-min)If the minimum allowable AC voltage drop is 30% (Vac-min=154V) and the voltage output of the LM2576  is 5V (Vmin=8V), when Vac=220V, the input DC voltage of the LM2576  should be greater than 11.5V, usually 12V.II Working ModeThe pin 5 input level of LM2576 can be used to control the working state of LM2576.   The pin 5 input level is compatible with the TTL level. When the input is low level,  LM2576  works normally; when the input is high level,  LM2576 stops output and enters a low power consumption state.Figure 2. Schematic diagram of controllable circuitIn Figure 2, The pull-down resistor can ensure the normal operation of LM2576 when the control terminal of mcu-con is low. The control end signal of shutdown input comes from MCU.  When the terminal of shutdown input is at a low level, LM2576 stops output, and the system enters into a low-power consumption state. When the terminal is high level, the transistor will make LM2576 work again. When the control terminal of MCU  -CON is high level and the triode is on, the resistance R will not damage the output control terminal of MCU due to over-current.FAQWhat type of voltage regulator is used to convert high DC voltage into working voltage required by MCU?78xx series three terminal voltage regulatorWhat is the working efficiency of the linear regulated power supply?30% - 50%What is one advantage of using LM2576 series switching power supply?High-frequency on-off characteristics of switch tubesWhere is LM2576 used?LM2576 is usually used as a voltage stabilizing device when the input and output voltage difference is large and the output current is also large. Because it is a switching regulator, it has a higher conversion efficiency and low heat generation than a linear regulator.What’s the difference between LM2576T-ADJ and LM2576S-ADJ?LM2576T-ADJ is the package of TO-220, LM2576S-ADJ is the package of TO-263-5, there is no difference in their functions.What is the difference between LM2940 and LM2576? Which circuit are they applicable to?LM2940 is a low-dropout linear stabilized integrated circuit. The linear stabilized power supply is characterized by a relatively simple circuit, high precision, and small ripple coefficient. It is suitable for precision power supplies with high voltage requirements. The disadvantage is that the efficiency is very low and the output The current is relatively small (relative to the switching power supply)LM2576 is a switching power supply integrated circuit. Switching power supply, the circuit is more complicated, but the output current is large, the efficiency is high, the disadvantage is that the accuracy is lower and the ripple coefficient is larger.Why do switching power supply chips LM2576 and LM2596 have diodes, inductors and capacitors behind the output pins?The function of the diode and the inductance is that the output current can be continuous when the LM25XX is in the off state, and the function of the capacitor is to prevent the output voltage from sudden changes when the LM25XX is turned on and off. In fact, it is filtering.Why the higher the switching frequency of LM2576 and LM2596, the smaller the output inductance and capacitance value?Quite simply, the capacitive reactance of a capacitor decreases as the frequency increases, and the inductance of an inductor increases as the frequency increases. That is to say, the effect of using an inductance of 33uH in the case of 150Khz is basically the same as the effect of using an inductance of 100uH in the case of 52khz, and the principle of capacitance is the same. LM2596 is an upgraded version of LM2576. But LM2576 also has the advantage of less switching loss and less interference.

S8050 is a low-power NPN silicon tube with a maximum collector-base (Vcbo) voltage of 40V and a collector current (Ic) of 0.5A. S8050 is one of the most commonly used semiconductor transistor models in circuit hardware design.Name: S8050Type: NPNDissipated power: 0.625W (SMD: 0.3W)Collector current: 0.5ABase voltage: 40VCatalogS8050 PinoutS8050 CircuitS8050 ApplicationS8050 FeaturesS8050 AdvantageS8050 AlternativesS8050 EquivalentsWhere & How to use S8050How to Safely Long Run S8050 in CircuitS8050 PinoutPin NumberPin NameSymbolDescription1EmitterECurrent Drains out through emitter2BaseBControls the biasing of transistor3CollectorCCurrent flows in through collectorS8050 ApplicationAudio amplification circuitsClass B amplifiersPush pull transistorsCircuits where high gain is requiredLow signal applicationsS8050 FeaturesLow Voltage, High Current NPN TransistorSmall Signal TransistorMaximum Power: 2 WattsMaximum DC Current Gain (hFE) is 400Continuous Collector current (IC) is 700mABase- Emitter Voltage (VBE) is 5VCollector-Emitter Voltage (VCE) is 20VCollector-Base Voltage (VCB) is 30VHigh Used in push-pull configuration doe Class B amplifiersAvailable in To-92 PackageNote: Complete Technical Details can be found at the S8050 datasheet given at the end of this page.S8050 AdvantageS8050 npn transistorS8050 is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin. It has a maximum gain value of 400; this value determines the amplification capacity of the transistor normally S8050. Since it is very high it is normally used for amplification purposes. However, at a normal operating collector current the typical value of gain will be 110. The maximum amount of current that could flow through the Collector pin is 700mA, hence we cannot drive loads that consume more than 700mA using this transistor. To bias a transistor we have to supply current to base pin, this current (IB) should be limited to 5mA.When this transistor is fully biased then it can allow a maximum of 700mA to flow across the collector and emitter. This stage is called Saturation Region and the typical voltage allowed across the Collector-Emitter (V­CE) or Collector-Base (VCB) could be 20V and 30V respectively. When base current is removed the transistor becomes fully off, this stage is called as the Cut-off Region.S8050 Alternatives2N3904, 2N3906, 2N2369, 2N3055, S9014, MPSA42, SS8050, BC547S8050 Equivalents2N5830, S9013S8050 CircuitThis is a video introducing transistors stereo amplifier S8050 and S8550.Where & How to use S8050S8050 transistor is a general-purpose transistor, it is a perfect transistor to perform small and general tasks in electronic circuits. You can use it as a switch in electronic circuits to switch on loads under 700mA. 700mA is enough to handle variety of loads for example relays, LEDs, bulbs etc. It can also be used as amplifier in small amplification stages or as a separate small signal amplifier.How to Safely Long Run S8050 in CircuitTo safely run S8050 transistor in your circuit or electronic projects do not operate this transistor from voltage higher than 20V and do not operate any load more than 700mA or 0.7A. Use a suitable base resistor which will limits the base current to its required level. Do not expose it to heat over 150 centigrade and below -60 Centigrade. 

This article first introduced the three commonly used stable output voltage circuits of UC3842, analyzed their respective advantages and disadvantages, and designed a new voltage feedback circuit on this basis. Experiments prove that this new circuit has a good voltage stabilizing effect.CatalogI. Common Voltage Feedback Circuits1.1 Direct voltage division of the output voltage as the input of the error amplifier1.2 Auxiliary power supply output voltage division as the input of the error amplifier1.3 Change the input error voltage of the error amplifier using linear optocouplerII. Experiments and Results2.1 Change the gain of error amplifier by using linear optocoupler2.2 Experimental resultsIII. ConclusionI. Common Voltage Feedback CircuitsGenerally, the PWM type switching power supply uses sampling of the output voltage as the feedback voltage of the PWM controller. After the feedback voltage is passed through the error amplifier inside the PWM controller, the duty cycle of the switching signal is adjusted to achieve the stability of the output voltage. But different voltage feedback circuits have different output voltage stability accuracy. The internal circuit diagram of UC3842 is shown as in Figure 1.UC3842 Internal Circuit 1.1 Direct voltage division of the output voltage as the input of the error amplifierAs shown in Figure 2, the output voltage Vo is divided by R2 and R4 and then used as a sampling signal and input to the UC3842 pin 2 (the reverse input of the error amplifier). The forward input of the error amplifier is connected to the reference voltage of 2.5V inside the UC3842. When the sampling voltage is less than 2.5V, the voltage difference between the forward and reverse outputs of the error amplifier is amplified by the amplifier to adjust the output voltage, making the duty cycle of the output signal of the UC3842 larger, the output voltage rises, and finally the output voltage is stabilized at the set voltage value.R3 and C1 are connected in parallel to form a current-type feedback. The advantage of this circuit is that the sampling circuit is simple, but the disadvantage is that the input voltage and output voltage must share the same ground and cannot be electrically isolated. This is easy to cause difficulty in power supply wiring, and the power supply works in a high-frequency switching state, which is easy to cause electromagnetic interference, which will inevitably bring difficulties in circuit design, so this method is rarely used.Figure 2 Sampling diagram for direct voltage division of output voltage 1.2 Auxiliary power supply output voltage division as the input of the error amplifierAs shown in Figure 3, when the output voltage rises, the induced voltage generated on the auxiliary winding of the single-ended flyback transformer T also rises, and the voltage is rectified, filtered and regulated by D2, D3, C15, C14, C13 and R15 to obtain a DC voltage to power the UC3842. At the same time, the voltage is divided by R2 and R4 as a sampling voltage and sent to the UC3842's pin 2. After comparing with the reference voltage, it is amplified by the error amplifier, so that the duty cycle of pin 6 output pulse becomes smaller and the output voltage drops to achieve the purpose of voltage regulation. Similarly, when the output voltage decreases, the duty cycle of the output pulse of pin 6 becomes larger and the output voltage rises, finally stabilizing the output voltage at the set value.Figure 3 Sampling Diagram for auxiliary power supply division of output voltage The advantage of this circuit is that the sampling circuit is simple, and there is no electrical path between the secondary winding, the primary winding and the auxiliary winding, which is easy to wire.  The disadvantage is that the sampling voltage is not obtained directly from the secondary winding, and the voltage stabilization effect is not that positive. It was found in the experiment that the voltage stabilization basically cannot be achieved when the load of the power supply varies greatly. The circuit is suitable for the case of a fixed load. 1.3 Change the input error voltage of the error amplifier using linear optocouplerAs shown in the figure 4, the voltage sampling circuit of the switching power supply has two circuits: one is the voltage of the auxiliary winding through D1, D2, C1, C2, C3, R9 rectification, filtering and voltage regulation to obtain 16V DC voltage to the UC3842 power supply, in addition, the voltage through R2 and R4 voltage division to obtain a sampling voltage, the sampling voltage mainly reflects the change of the DC bus voltage. The other is the photocoupler, three-terminal adjustable regulator Z and R4, R5, R6, R7, R8 voltage sampling circuit, the road voltage reflects the change in the output voltage; when the output voltage rises, the reference voltage of the input Z also rises after the resistor R7 and R8 divides the voltage, the regulator voltage value of the regulator rises, the current flowing through the light-emitting diode in the photocoupler decreases, the current flowing through the phototransistor in the photocoupler also correspondingly reduced, the error amplifier input feedback voltage is reduced, resulting in the UC3842 pin 6 output drive signal duty cycle becomes smaller, so the output voltage drops, to achieve the purpose of voltage regulation.Figure 4 Auxiliary power sampling and optocoupler sampling synthesis Since the circuit uses an opto-coupler, it achieves the isolation of output and input, the isolation of weak and strong power, reducing electromagnetic interference, thus its anti-interference ability is improved, and it is to the output voltage sampling, with good voltage regulation performance. The disadvantage of the circuit is the increase in external components, which increases the difficulty of wiring and adds the cost of the power supply. II. Experiments and Results2.1 Change the gain of error amplifier by using linear optocoupler As shown in Figure 5, the voltage sampling and feedback circuit consists of R2, R5, R6, R7, R8, C1, opto-coupler, and three-terminal adjustable regulator Z. When the output voltage rises, the output voltage is divided by R7 and R8 to obtain the sampling voltage (i.e., Z's reference voltage) also rises, Z's regulator value also rises, the current flowing through the light-emitting diode in the photocoupler decreases, resulting in a reduction in the current flowing through the phototransistor. This is equivalent to C1 parallel variable resistor resistance value becomes large (the equivalent resistance value by the flow of light-emitting diode current control), the gain of the error amplifier becomes large, resulting in the UC3842 pin 6 output of the drive signal duty cycle becomes small, the output voltage drops to achieve the purpose of voltage regulation. When the output voltage decreases, the gain of the error amplifier becomes smaller and the duty cycle of the output switching signal becomes larger, which eventually stabilizes the output voltage at the set value. Because the voltage feedback input pin 2 of UC3842 is grounded, so the input error of the error amplifier is always fixed, and what changes is the gain of the error amplifier (the phototransistor in the linear optocoupler can be regarded as a variable resistor), and its equivalent circuit diagram is shown in Figure 6.Figure 5 Varying the gain of the error amplifier using an optocouplerFigure 6 Equivalent circuit for changing the gain of the error amplifier The circuit changes the output of the error amplifier by adjusting the gain of the error amplifier instead of adjusting the input error of the error amplifier, thus changing the duty cycle of the switching signal. This topology not only has fewer external components, but also employs a three-terminal adjustable regulator in the voltage sampling circuit, making the output voltage essentially unchanged when the load changes significantly. The experiment proves that the circuit has a very good voltage regulation effect compared with the above three feedback circuits. 2.2 Experimental resultsThis new voltage feedback circuit using a linear optocoupler to change the gain of the error amplifier is used in a 48V/12V single-ended flyback DC/DC switching power supply (maximum output current of 5A), which shows that the output voltage of the power supply is stable and has a strong load carrying capability. Figure 7(a)-(h) gives the output voltage and drive waveforms when the load is 100Ω, 25Ω, 10Ω, and 3Ω, respectively. From the waveforms, it can be seen that when the load current gradually increases, the duty cycle of the drive signal increases accordingly, but the output voltage is always stable at 12.16V.Figure 7 Output voltage and drive waveform at different loads III. ConclusionIn the single-ended isolated PWM power supply, the current-mode pulse width modulator UC3842 has a wide range of applications. This article summarizes the voltage feedback circuit design that uses a linear optocoupler to change the gain of the UC3842 error amplifier. And it is proved by experiments that the new voltage feedback circuit has high voltage regulation accuracy and strong load adaptability. 

Temperature setting controller is widely used in high and low voltage power distribution cabinets, terminal boxes, substations, used for real-time detection of environmental temperature and humidity changes, and the protection of power electronics devices. It is also commonly used in places requiring temperature and humidity detection and comprehensive control, such as vegetable greenhouses, granaries, etc.  This paper designs a temperature setting controller which used temperature sensor AD592, lon sensor HDP 07 as a detecting component, with four channels of integrated op-amp LM324 as a core control element, it automatically measures and detect the environment temperature, control output, and gives an alarm and protect condensation, etc... It overcomes the shortcomings of existing thermocoagulation controllers that require high software knowledge for design, debugging, and maintenance personnel, complex circuit structure and large temperature response deviation, and simplifies the circuit structure.CatalogI.Control Principle of Temperature Setting ControllerII.Circuit Design  2.1 DC Voltage Regulation  2.2 Partly Design of Temperature Setting ControlIII. The text 3.1 Adjustment and Testing of Temperature Control 3.2 Adjustment and Testing of Condensation ControlIV. ConclusionFAQOrdering & Quantity I.Control Principle of Temperature Setting ControllerThe LM324 voltage comparator is used as the main control chip of the temperature condensation controller. The temperature sensor is used to convert the temperature change into the current change, and the condensation sensor is used to convert the humidity change into the resistance change. The LM324 voltage comparator controls the temperature condensation Controller to achieve alarm display and output. The principle block diagram of the temperature condensation controller based on the LM324 voltage comparator is shown in Figure 1.Figure 1: Block Diagram of LM324 Based Temperature Condensation ControllerII.Circuit DesignThe circuit design of the temperature condensation controller based on LM324 voltage comparison mainly includes the design of two parts, the DC stabilized power supply and the temperature condensation control,  The main components of the controller include temperature and humidity sensors, which are connected to the control circuit board through the base through four wires of red, blue, black and yellow, and the dial connected to the control circuit board, and finally packaged by the shell. 2.1 DC Voltage RegulationThe power supply part of the temperature coagulation controller circuit designed in this paper is composed of a DC stabilized power supply module, a sensor input module, an alarm display module, a voltage comparison module, etc. Basically, all electronic products are powered by a DC power supply, and the daily grid voltage is AC 220V, so the AC power must first be converted into DC power to provide a stable DC power supply for the circuit. This thermocoagulation controller needs to provide 8V for the voltage comparison module It also provides 12V DC for the output relay module. After voltage regulation by the transformer, it is rectified by a bridge rectifier circuit composed of four diodes, filtered by a capacitor, and output by a three-terminal integrated voltage regulator. 2.2 Partly Design of Temperature Setting Control The temperature condensation control part design adopts an LM324 voltage comparator as the main control chip of the whole temperature condensation control circuit. LM324 is a four-channel integrated operational amplifier with a true differential input. It is composed of four groups of completely independent operational amplifiers. Its main function in the circuit is to compare the input voltage and the reference voltage, change the output voltage according to the level of the two-channel voltage， and perform the corresponding control output.This thermocoagulation controller uses AD592  as the temperature sensor. AD592  is an integrated temperature sensor. It is a high-performance current sensor launched by American  Analog Devices, which converts temperature changes into the current. It has the advantages of small error, low cost, temperature change, and current change into linearity. Its output current is based on absolute zero (-273°C). For every 1°C increase or decrease in the ambient temperature, it will increase the output current by 1 microampere. The temperature sensor converts the temperature change into a voltage change through a voltage follower and then inputs it to the inverting input terminal of the voltage comparator. The wire-wound potentiometer is connected to the dial to provide a reference voltage and provide it to the non-inverting input terminal of the voltage comparator. If the input voltage of the LM324 voltage comparator is lower than the reference voltage, it means that the ambient temperature is lower than the setting temperature of the dial, and the voltage comparator outputs a high level. At this time, the diode displays an alarm and controls the output. Increase the temperature until the ambient temperature is higher than the settting temperature, the voltage comparator outputs a low level, and the entire temperature control process is a closed-loop system, which can quickly and sensitively control the action of the temperature condensation controller. Figure 2 is the circuit schematic diagram of the temperature control module.Figure 2: Schematic Diagram of the Temperature Control ModuleThis temperature condensation controller selects HDP-07 as the condensation sensor. HDP-07 is a new type of condensation sensor that measures or predicts the occurrence of air condensation through changes in its resistance. Its structure is to make a tree-like current on a ceramic substrate and then coat it with resin and conductive particles to form a resistive film. It has the characteristics of a typical switch-type sensor, which is extremely sensitive to high humidity and presents a high resistance state; in a low humidity environment, it reflects a low resistance state. It has the advantages of small size, short measurement period, quick response, high precision, etc. It overcomes the shortcomings of a complex structure, large volume, complex operation, and low precision of the chilled mirror condensation sensor made of traditional optical principles. It is widely used on occasions that need to control high humidity and condensation. Figure 3 is a schematic diagram of the humidity control module.Figure 3：Schematic Diagram of the Humidity Control ModuleWhen the relative humidity in the ambient temperature reaches 100%, the water vapour in the air will liquefy and condense into dew, and the equipment will malfunction due to humidity and reduce the service life. Therefore, the temperature condensation controller designed in this paper (using the HDP-07 condensation sensor) is used to detect the occurrence of condensation and eliminate it in time. The condensation sensor and the comparator constitute a zero-crossing comparator. Usually, in a low humidity environment, the resistance of the condensation sensor is very small. The sensor reflects the character of switch closure, and the comparator outputs a low level; when the ambient humidity reaches 83% at the critical value, the condensation sensor presents a high-impedance state, and the comparator outputs a high level, to control the electronic switch triode to turn on and display the alarm and control the output to reduce humidity. The temperature condensation based on the LM324 voltage comparator is used as the main control chip compared with the circuit based on software control, the control circuit has a simpler circuit structure, more convenient debugging and assembly use, and lower cost. III.The Text3.1 Adjustment and Testing of Temperature Control(1) BenchmarkTurn the dial scale to 0 degrees, clamp the red test pen of the multimeter to the middle tap of the wire-wound potentiometer, ground the black test pen, turn the multimeter to the DC voltage range, adjust the potentiometer W2, and make the voltmeter read 2.73V. (2) Linear adjustment accuracyFirst, adjust the dial scale to -30 degrees, adjust the potentiometer W2, so that the voltage reading is 2.43V; the second step, adjust the dial scale to 40 degrees, write down the value of the multimeter, if the value is greater than 3.13V, it indicates the slope is too large, then adjust the dial scale to 30 degrees, adjust the potentiometer W1 and re-adjust W2, the voltage reading is 2.43, and then adjust the dial scale to 40 degrees, observe whether the voltmeter reading is 3.13V, if not, repeat step two until the voltage reading is 2.43V. (3) Adjust the accuracy of the temperature sensorAdjust the dial scale to room temperature, adjust the potentiometer WS, so that the temperature alarm indicator diode is on, and adjust the potentiometer back and forth at this critical value, and the temperature indicator will change between on and off in a short time. (4) TestAdjust the dial scale to be lower than room temperature, the temperature condensing controller does not work; adjust the dial scale to higher than room temperature, the temperature alarm indicator of the temperature condensing controller is on, the relay is closed, and the output 220V alternating current indicates that the temperature control part is working normally. 3.2 Adjustment and Testing of Condensation ControlWhen the condensation controller detects, it can add water vapour or breathe on the condensation sensor with the mouth for about 5 seconds. The humidity alarm indicator on the controller is on, the relay is closed, and the output is 220V AC, indicating that the condensation control part can work normally. IV. ConclusionThis article summarizes the design and production of the temperature condensation controller based on the LM324 voltage comparator. The temperature coagulation controller has successfully realized temperature control and condensation generation control through the test. It has the advantages of good stability, strong anti-interference ability, wide adjustment range, high precision, and rapid response. It solves the complex circuit structure of the temperature coagulation controller. , The response accuracy is not high. Only the LM324 voltage comparator is used as the main control chip of the control circuit, which is convenient for assembly and debugging low cost, and does not need to use software control, those are the characteristics of the thermocoagulation controller. It’s suitable for technological innovation and promotion.FAQWhat is widely used in high and low voltage power distribution cabinets?Temperature setting controllerWhat is used to convert the temperature change into the current change?Temperature sensorWhat is lm324?LM324 is a Quad op-amp IC integrated with four op-amps powered by a common power supply. The differential input voltage range can be equal to that of the power supply voltage. Generally, op-amps can perform mathematical operations.Which is the difference between lm324 and lm339?The LM324 has a complementary output while the LM339 is open collector. In the complementary output, current can flow in either direction as required (either source or sink) while the open collector output can only sink current.What is op-amp used for?Operational amplifiers are linear devices that have all the properties required for nearly ideal DC amplification and are therefore used extensively in signal conditioning, filtering or to perform mathematical operations such as add, subtract, integration and differentiation.How does an op-amp work?What is lm324 used for?LM324 IC ApplicationsThe applications of IC LM324 include the following. By using this IC, conventional op-amp applications can be implemented very simply. This IC can be used as oscillators, rectifiers, amplifiers, comparators etc.What is the function of a temperature controller?A Temperature Controller is a device that is used to control a heater or other equipment by comparing a sensor signal with a set point and performing calculations according to the deviation between those values.