The Kynix Components

The UA741 device is a general-purpose operational amplifier with offset voltage clearing function.CatalogDescription of UA741UA741 PinoutUA741 CADApplicationsQuality InformationSpecificationsFeatures of UA741Alternatives for UA741CPUA741 CircuitLM741CN vs UA741CPUA741CP DatasheetWarningsFAQ Description of UA741UA741 amplifier has a high common-mode input voltage range and no latch, so it is an ideal choice for voltage follower applications. The device has short-circuit protection, and internal frequency compensation can ensure stability without the need for external components. A low-value potentiometer can be connected between the offset voltage clear input to clear the offset voltage, as shown in Figure.The rated operating temperature range of the µA741C device is 0°C to 70°C. UA741 PinoutLabeled pinout diagram of any equipment provides help in better understanding of the user.A completely labeled diagram of  UA 741 along with its animation and schematic is given below.The complete pin diagram along with animation, symbolic representation and the real image of UA-741 is shown in the figure below.  UA741 Pinout UA741 CAD UA741 CAD ApplicationsDVD Recorders and PlayersPro Audio MixersApplication NotesUnderstanding Operational Amplifier SpecificationsSelecting the right operational amplifier for a specific application requires you to have your design goals clearly in mind along with a firm understanding of what the published specifications mean. This paper addresses the issue of understanding data she | DocHandbook of Operational Amplifier Applications (Rev. B)While in the process of reviewing Texas Instruments applications notes, including those from Burr-Brown – I uncovered a couple of treasures, this handbook on op amp applications and one on active RC networks. These old publications, from 1963 and 1966, r | Doc. Quality InformationRoHSYesREACHYesPin Plating/Ball MaterialNIPDAUMSL grade/peak reflow soldering temperatureN/A for Pkg TypeQuality, reliability and package data download View or download SpecificationsProduct AttributeAttribute ValueManufacturer:Texas InstrumentsProduct Category:Operational Amplifiers - Op AmpsRoHS:DetailsMounting Style:Through HolePackage / Case:PDIP-8Output Current per Channel:25 mAVos - Input Offset Voltage:6 mVMinimum Operating Temperature:0 CMaximum Operating Temperature:+ 70 CIb - Input Bias Current:500 nAOperating Supply Current:1.7 mACMRR - Common Mode Rejection Ratio:90 dBSeries:UA741Packaging:TubeAmplifier Type:General Purpose AmplifierHeight:4.57 mmLength:9.81 mmProduct:Operational AmplifiersSupply Type:DualTechnology:BipolarWidth:6.35 mmBrand:Texas InstrumentsDual Supply Voltage:+/- 5 V, +/- 9 V, +/- 12 V, +/- 15 VMaximum Dual Supply Voltage:+/- 18 VMinimum Dual Supply Voltage:+/- 3.5 VOperating Supply Voltage:+/- 3.5 V to +/- 18 VPd - Power Dissipation:500 mW (1/2 W)Product Type:Op Amps - Operational AmplifiersFactory Pack Quantity:50Subcategory:Amplifier ICsVcm - Common Mode Voltage:Negative Rail + 3 V to Positive Rail - 3 VVoltage Gain dB:106.02 dBUnit Weight:0.015535 oz Features of UA741Short circuit protectionOffset voltage clear functionWide common mode and differential voltage rangeNo frequency compensation requiredNo latch Alternatives for UA741CPManufacturer Part NumberNewark Part No.Manufacturer / DescriptionUA741CP29AH8348TEXAS INSTRUMENTS，IC, OP AMP, SINGLE, 33MA, 05V/USUA741CDT 89K1783STMICROELECTRONICSOperational Amplifier, Single, 1 Amplifier, 1 MHz, 0.5 V/µs, 5V to 40V, SOIC, 8 Pins,ONSEMIMC34071DG 45J1214Operational Amplifier, Single, 1 Amplifier, 4.5 MHz, 13 V/s, 3V to 44V, SOIC, 8 Pins,ANALOG DEVICESOP27GPZ34X1906Operational Amplifier, Single, 8 MHz, 1, 2.8 V/ s, 4V to 18V, DIP, 8 RoHS Compliant: YesUA741 CircuitSchematic representation of an equipment presents the internal functionality of that equipment.A labeled schematic diagram of UA-741 is given in the figure shown below. Schematic  LM741CN vs UA741CP LM741CNUA741CPRohs CodeNoYesPart Life Cycle CodeObsoleteActiveIhs ManufacturerMOTOROLA INCTEXAS INSTRUMENTS INCPackage DescriptionDIP, DIP8,.3DIP, DIP8,.3Reach Compliance CodeunknowncompliantECCN CodeEAR99EAR99HTS Code8542.33.00.018542.33.00.01Amplifier TypeOPERATIONAL AMPLIFIEROPERATIONAL AMPLIFIERArchitectureVOLTAGE-FEEDBACKVOLTAGE-FEEDBACKFrequency CompensationYESYESInput Offset Voltage-Max7500 V7500 VJESD-30 CodeR-PDIP-T8R-PDIP-T8JESD-609 Codee0e4Low-OffsetNONONeg Supply Voltage-Nom (Vsup)-15 V-15 VNumber of Functions11Number of Terminals88Operating Temperature-Max70 C70 COperating Temperature-Min  Package Body MaterialPLASTIC/EPOXYPLASTIC/EPOXYPackage CodeDIPDIPPackage Equivalence CodeDIP8,.3DIP8,.3Package ShapeRECTANGULARRECTANGULARPackage StyleIN-LINEIN-LINEPower Supplies+-15 V+-15 VQualification StatusNot QualifiedNot QualifiedSupply Voltage-Nom (Vsup)15 V15 VSurface MountNONOTechnologyBIPOLARBIPOLARTemperature GradeCOMMERCIALCOMMERCIALTerminal FinishTin/Lead (Sn/Pb)Nickel/Palladium/Gold (Ni/Pd/Au)Terminal FormTHROUGH-HOLETHROUGH-HOLETerminal Pitch2.54 mm2.54 mmTerminal PositionDUALDUALBase Number Matches112Source Content uid UA741CPPbfree Code YesPart Package Code DIPPin Count 8Factory Lead Time 6 WeeksSamacsys Description Single op-amp,UA741CP 1MHz DIP8, tube Texas Instruments UA741CP Op Amp, 1MHz, 8-Pin PDIPSamacsys Manufacturer Texas InstrumentsAverage Bias Current-Max (IIB) 0.8 ABias Current-Max (IIB) @25C 0.5 ACommon-mode Reject Ratio-Min 70 dBCommon-mode Reject Ratio-Nom 90 dBInput Offset Current-Max (IIO) 0.2 ALength 9.81 mmLow-Bias NOMicropower NONeg Supply Voltage Limit-Max -18 VPacking Method TUBEPeak Reflow Temperature (Cel) NOT SPECIFIEDPower NOProgrammable Power NOSeated Height-Max 5.08 mmSlew Rate-Nom 0.5 V/usSupply Current-Max 2.8 mASupply Voltage Limit-Max 18 VTime@Peak Reflow Temperature-Max (s) NOT SPECIFIEDUnity Gain BW-Nom 1000 kHzVoltage Gain-Min 15000Wideband NOWidth 7.62 mmUA741CP DatasheetUA741CP DatasheetWarningsUA741 device has limited built-in ESD protection. The leads should be shorted together or device placed in conductive foam during storage or handling to prevent electrostatic damage to MOS gates. FAQWhat is the rated operating temperature range of the UA741C device?0°C to 70°C What provides help in better understanding of the user?UA741 Pinout Labeled pinout diagram What does the UA741 have?High common-mode input voltage range and no latch 

DescriptionThe PIC24FJ64GA004 family offers a new migration option for those high-performance applications which may be outgrowing their 8-bit platforms, but don’t require the numerical processing power of a digital signal processor. CAD Models Figure: Symbol  Figure: PCB Footprints  Figure: 3D Model Pin Diagram Figure: Pin Diagram Block Diagram Figure: Block Diagram FeaturesSpecial Microcontroller FeaturesOperating Voltage Range of 2.0V to 3.6V5.5V Tolerant Input (digital pins only)High-Current Sink/Source (18 mA/18 mA) on All I/O PinsFlash Program Memory:- 10,000 erase/write- 20-year data retention minimumPower Management modes:- Sleep, Idle, Doze and Alternate Clock modes- Operating current: 650 mA/MIPS, typical at 2.0V- Sleep current: 150 nA, typical at 2.0VFail-Safe Clock Monitor (FSCM) Operation:- Detects clock failure and switches to on-chip,low-power RC oscillatorOn-Chip, 2.5V Regulator with Tracking modePower-on Reset (POR), Power-up Timer (PWRT)and Oscillator Start-up Timer (OST)Flexible Watchdog Timer (WDT) with On-Chip,Low-Power RC Oscillator for Reliable OperationIn-Circuit Serial Programming™ (ICSP™) andIn-Circuit Debug (ICD) via 2 PinsJTAG Boundary Scan Support Analog Features10-Bit, up to 13-Channel Analog-to-Digital Converter:- 500 ksps conversion rate- Conversion available during Sleep and IdleDual Analog Comparators with ProgrammableInput/Output Configuration Peripheral FeaturesPeripheral Pin Select (PPS):- Allows independent I/O mapping of many peripherals- Up to 26 available pins (44-pin devices)- Continuous hardware integrity checking and safetyinterlocks prevent unintentional configuration changes8-Bit Parallel Master/Slave Port (PMP/PSP):- Up to 16-bit multiplexed addressing, with up to11 dedicated address pins on 44-pin devices- Programmable polarity on control linesHardware Real-Time Clock/Calendar (RTCC):- Provides clock, calendar and alarm functionsProgrammable Cyclic Redundancy Check (CRC)Two 3-Wire/4-Wire SPI modules (support 4 Framemodes) with 8-Level FIFO BufferTwo I2C™ modules Support Multi-Master/Slavemode and 7-Bit/10-Bit AddressingTwo UART modules:- Supports RS-485, RS-232, and LIN/J2602- On-chip hardware encoder/decoder for IrDA®- Auto-wake-up on Start bit- Auto-Baud Detect- 4-level deep FIFO bufferFive 16-Bit Timers/Counters with Programmable PrescalerFive 16-Bit Capture InputsFive 16-Bit Compare/PWM OutputsConfigurable Open-Drain Outputs on Digital I/O PinsUp to 3 External Interrupt Sources DatasheetYou can download the datasheet the link given below.PIC24FJ64GA004-I-P/T-Datasheet SpecificationsProduct AttributeAttribute ValueManufacturer:MicrochipProduct Category:16-bit Microcontrollers - MCUSeries:PIC24FJxxGA00xMounting Style:SMD/SMTPackage / Case:TQFP-44Core:PIC24FProgram Memory Size:64 kBData Bus Width:16 bitADC Resolution:10 bitMaximum Clock Frequency:32 MHzNumber of I/Os:35 I/OData RAM Size:8 kBSupply Voltage - Min:2 VSupply Voltage - Max:3.6 VMinimum Operating Temperature:- 40 ℃Maximum Operating Temperature:+ 85 ℃Qualification:AEC-Q100Packaging:TrayBrand:Microchip Technology / AtmelData RAM Type:RAMHeight:1 mmInterface Type:I2C, IrDA, SPI, UARTLength:10 mmMoisture Sensitive:YesNumber of ADC Channels:13 ChannelNumber of Timers/Counters:5 TimerProcessor Series:PIC24FProduct:MCUProduct Type:16-bit Microcontrollers - MCUProgram Memory Type:FlashFactory Pack Quantity:160Subcategory:Microcontrollers - MCUTradename:PICWidth:10 mmUnit Weight:0.077179 oz ManufacturerMicrochip Technology Inc. is a publicly-listed American corporation that manufactures microcontroller, mixed-signal, analog and Flash-IP integrated circuits. Its products include microcontrollers (PIC, dsPIC, AVR and SAM), Serial EEPROM devices, Serial SRAM devices, embedded security devices, radio frequency (RF) devices, thermal, power and battery management analog devices, as well as linear, interface and wireless products. Using WarningNote: Please check their parameters and pin configuration before replacing them in your circuit. FAQWhat is a flash microcontroller and how does it work?With a flash microcontroller, all that is required is an electrical connection to one of the microcontroller's communications ports, such as RS-232, CAN, LIN or USB. New code can be downloaded without any physical access to the microcontroller being required, which means that manufacturers can design easily upgradable products. What are the advantages of 16-bit microcontrollers?A 16-bit microcontroller is one that can handle data with 16 bits, allowing it to manage a bigger quantity of data and calculations at once. It also consumes less power and has a faster clock speed than an 8-bit microcontroller. It is now the most widely used microcontroller. How many pins are in a 16-bit microcontroller?The available 119 I/O pins (of which 25 can generate interrupts) can implement a standard external bus interface for high-speed parallel connections to external memory or peripherals like TFTs. 

Product OverviewThe Kintex® UltraScale™ FPGA KCU105 Evaluation Kit is the perfect development environment for evaluating the cutting edge Kintex UltraScale FPGAs. The Kintex UltraScale family delivers ASIC-class system-level performance, clock management, and power management for next generation systems at the right balance of price, performance and power. CatalogProduct OverviewKCU105 PCLe ExampleKey Features & BenefitsBoard FeaturesKCU105 Board System ClockDual Quad-SPI Flash MemoryMicro-SD Card InterfaceKCU105 ApplicationsKCU105 SpecificationKCU105 SchematicsKCU105 DatasheetManufacturerUsing WarningsFAQ KCU105 PCLe Example Create a Tandem PCIe Design for the KCU105  Key Features & BenefitsOptimized for quickly prototyping applications using Kintex UltraScale FPGAs with access to the following features64-bit DDR4 Component MemoryDual SFP+ cages for EthernetPCIe Gen3 x82x FPGA Mezzanine Card (FMC) interface for I/O expansion Board Features Board Features ConfigurationOnboard JTAG configuration circuitry to enable configuration over USBJTAG header provided for use with Xilinx download cables such as the Platform Cable USB IIQuad SPI Flash with 2 x 256 Mb of non-volatile storage Memory2GB DDR4 component memory (four [256 Mb x 16] devices) at 1200MHz / 2400Mbpsps64MB (512Mb) Quad SPI Flash8Kb IIC EEPROMMicro SD Card Slot Communication & NetworkingGigabit Ethernet GMII, RGMII and SGMII2x SFP / SFP+ cageGTX port (TX, RX) with four SMA connectorsUART To USB BridgePCI Express x8 edge connector Expansion ConnectorsFMC-HPC (Partial Population) connector (8 GTX Transceiver, 114 single-ended or 57 differential (34 LA & 24 HA) user defined signals)FMC-LPC connector (1 GTX Transceiver, 68 single-ended or 34 differential user defined signals)2x PMOD headersIICDisplayHDMI Video outputExternal Phy/codec device driving an HDMI Connector8x  GPIO user LEDs Clocking8x programmable clocksSystem clocks, EMC clock, user clocks, Jitter attenuated clocks2x SMA input clocks Control & I/O5X Directional Push Buttons4X DIP Switches1x Rotary switchDiff Pair I/O (1 SMA pair) Power12V wall adapter or ATX KCU105 Board System Clock KCU105 Board System Clock Dual Quad-SPI Flash MemoryThe Figure shows the connections of the linear Quad-SPI flash memory on the KCU105 evaluation board. For more details, see the Micron N25Q256A11ESF40F data sheet at the Micron website [Ref 5]. Dual Quad-SPI 256 Mb Flash Memory  Micro-SD Card Interface The Figure shows the connections of the SD card interface on the KCU105 board.SD Connector Circuit Topology KCU105 ApplicationsEmbedded Design & Development KCU105 Specification Product AttributeAttribute ValueManufacturer:XilinxProduct Category:Programmable Logic IC Development ToolsProduct:Evaluation KitsType:FPGATool Is For Evaluation Of:XCKU040-2FFVA1156EBrand:XilinxProduct Type:Programmable Logic IC Development ToolsSubcategory:Development ToolsUnit Weight:6 lbs KCU105 SchematicsKCU105 Schematics KCU105 Datasheet KCU105 Eval Kit Quick Start Guide KCU105 Board Guide KCU105 PCI Express Control Plane TRD User Guide ManufacturerXilinx is the inventor of the FPGA, programmable SoCs, and now, the ACAP. Our highly-flexible programmable silicon, enabled by a suite of advanced software and tools, drives rapid innovation across a wide span of industries and technologies - from consumer to cars to the cloud. Xilinx delivers the most dynamic processing technology in the industry, enabling rapid innovation with its adaptable, intelligent computing. Using WarningsNote: Please check their parameters and pin configuration before replacing them in your circuit. FAQWhat do KCU105 evaluation board provide?The KCU105 evaluation board provides features common to many evaluation systems, including a DDR4 component memory, a high definition multimedia interface (HDMI™), two small form-factor pluggable (SFP+) connectors, an eight-lane PCI Express® interface, an Ethernet PHY, general purpose I/O and two UART interfaces. What are the applications of KCU105?Embedded Design & Development

BME280 is an environmental sensor that integrates onboard temperature sensor, humidity sensor and barometer. The sensor is of high precision, multiple functions, and small size etc. It provides both SPI and I2C interfaces, which make it easy to make a fast prototypes. It can be widely used in environmental monitoring, story height measurement and Internet of Things (IoT) control and so on.Down below is a tutorial video shows how to use BME280 with Arduino: CatalogBME280 General DescriptionBME280 PinoutBME280 Absolute Maximum RatingsBME280 SpecificationBME280 Block DiagramBME280 FeaturesBME280 CAD ModelsBME280 ApplicationsBME280 PackageBME280 Popularity by RegionBME280 Market Price AnalysisBME280 ManufacturerComponent DatasheetFAQ BME280 General DescriptionThe BME280 is as combined digital humidity, pressure and temperature sensor based on proven sensing principles. The sensor module is housed in an extremely compact metal-lid LGA package with a footprint of only 2.5 × 2.5 mm² with a height of 0.93 mm. Its small dimensions and its low power consumption allow the implementation in battery driven devices such as handsets, GPS modules or watches. The BME280 is register and performance compatible to the Bosch Sensortec BMP280 digital pressure sensor. The BME280 achieves high performance in all applications requiring humidity and pressure measurement. These emerging applications of home automation control, in-door navigation, fitness as well as GPS refinement require a high accuracy and a low TCO at the same time.The humidity sensor provides an extremely fast response time for fast context awareness applications and high overall accuracy over a wide temperature range.The pressure sensor is an absolute barometric pressure sensor with extremely high accuracy and resolution and drastically lower noise than the Bosch Sensortec BMP180.The integrated temperature sensor has been optimized for lowest noise and highest resolution. Its output is used for temperature compensation of the pressure and humidity sensors and can also be used for estimation of the ambient temperature.  BME280 Pinout                     Note: The pin numbering of BME280 is performed in the untypical clockwise direction when seen in the top view and counter-clockwise when seen in the bottom view BME280 Pin Description: BME280 Absolute Maximum RatingsBME280 SpecificationTYPEDESCRIPTIONCategoriesSensors, Transducers/Humidity, Moisture SensorsManufacturerBosch SensortecSeries-PackagingCut Tape (CT) Part StatusActiveSensor TypeHumidity, Pressure, TemperatureHumidity Range0 ~ 100% RHOutput TypeI²C, SPIOutput16bAccuracy±3%Response Time1sSensitivity-Voltage - Supply1.71V ~ 3.6VMounting TypeSurface MountOperating Temperature-40°C ~ 85°CPackage / Case8-VFLGASupplier Device Package8-LGA (2.5x2.5) BME280 Block DiagramBME280 FeaturesCompatible with 3.3V/5V microcontrollersEnvironmental monitoring: temperature, humidity and barometerGravity I2C interface and reserve XH2.54 SPI interfaceSmall size, convenient to installBME280 CAD Models Part Symbol FootprintBME280 ApplicationsContext awareness, e.g. skin detection, room change detectionHome automation control (control heating, venting, air conditioning (HVAC))Internet of thingsGPS enhancement (e.g. time-to-first-fix improvement, dead reckoning, slope detection)Indoor navigation (change of floor detection, elevator detection)Outdoor navigation, leisure and sports applicationsWeather forecastVertical velocity indication (rise/sink speed) BME280 PackageBME280 Popularity by RegionBME280 Market Price AnalysisBME280 ManufacturerBosch Sensortec GmbH, a fully owned subsidiary of Robert Bosch GmbH, develops and markets a wide portfolio of microelectromechanical systems (MEMS) sensors and solutions tailored for smartphones, tablets, wearables and hearables, AR/VR devices, drones, robots, smart home and IoT (Internet of Things) applications.  Component DatasheetBME280 Sensor DatasheetFAQWhat is bme280?The BME280 is a humidity sensor especially developed for mobile applications and wearables where size and low power consumption are key design parameters. The unit combines high linearity and high accuracy sensors and is perfectly feasible for low current consumption, long-term stability and high EMC robustness.How does bme280 work?The BME280 sensor module reads barometric pressure, temperature, and humidity. Because pressure changes with altitude, you can also estimate altitude. There are several versions of this sensor module. The BME280 sensor uses I2C or SPI communication protocol to exchange data with a microcontroller.How do I connect my raspberry Pi to bme280?Wiring1.Connect the Raspberry Pi 3.3V power pin to Vin.2.Connect the Raspberry Pi GND pin to GND.3.Connect the Pi SDA pin to the BME280 SDI.4.Connect the Pi SCL pin to to the BME280 SCKHow to interface a bme280 with arduino?Wiring BME280 Module to Arduino UNOConnections are fairly simple. Start by connecting VIN pin to the 5V output on the Arduino and connect GND to ground. Now we are remaining with the pins that are used for I2C communication. Note that each Arduino Board has different I2C pins which should be connected accordingly.What are i2c sensors?The I2C bus is a simple and flexible way to transfer digital data between two electronic devices which may be physically seperate or contained on the same printed circuit board (PCB).How do I use i2c with a bme280 sensor?The BME280 supports either SPI or I2C interface to communicate with the micro controller. Because of the small size of the sensor, the best way to use this sensor is with a breakout board. The Adafruit breakout board is used here. In this hookup we are only connecting one device to the Arduino using the I2C bus. We can use either address (0x77 or 0x76). It reads the barometric pressure, humidity and temperature and displays it on the console. More>>How do I get started with a bme280 sensor?The BME280 is an integrated environmental sensor developed specifically for mobile applications where size and low power consumption are key design constraints. The unit combines individual high linearity, high accuracy sensors for pressure, humidity and temperature in an 8-pin metal-lid 2.5 x 2.5 x 0.93 mm³ LGA package, designed for low current consumption (3.6 μA @1Hz), long term stability and high EMC robustness. More>>How can I use Python to read a bme280 sensor?The BME280 device is a digital barometric pressure sensor and is a slightly upgraded version of the BMP180. This is available on a small module which provides access to the sensor via the I2C interface. This allows us to easily connect it to the Raspberry Pi and read the data using Python. The BME280 provides temperature, pressure and humidity. More>>Where can I download the bme280 library?Provides an Arduino library for reading and interpreting Bosch BME280 data over I2C, SPI or Sw SPI. Additional environment calculation functions are provided. ESP and BRZO are now supported. More>> 

The differential amplifier circuit is also called the differential circuit.It can not only effectively amplify the AC signal, but also effectively reduce the zero drift caused by the power supply fluctuation and the temperature change of the transistor, so it has been widely used. Especially, it is widely used in integrated operational amplifier circuits, and it is often used as the pre-stage of multi-stage amplifiers.Starting from actual production design, this blog discusses the shortcomings of discrete resistors, filtering, AC common mode rejection, and high noise gain.What a Differential Amplifier is along with the Derivation of the Equation Relating Input to OutputCatalogI Classic Four-resistor Differential AmplifierII CMRRIII Low Tolerance ResistanceIV Another Low-end Detection ApplicationV High Noise GainVI Single Capacitor Roll-offVII Capacitance between Input Terminals of Op AmpVIII ConclusionI Classic Four-resistor Differential AmplifierFigure 1 shows the classic four-resistor differential amplifier is very useful.Figure 1. Classical differential amplifierThe transfer function of this amplifier is:If R1 = R3 and R2 = R4, then Equation 1 is simplified to:This simplified theory works, but it cannot be done in reality. Because the resistance can never be exactly equal. In addition, other changes in the basic circuit can produce unexpected behavior. Although the following example is simplified to show the essence of the problem, it is derived from actual application problems.II CMRRAn important function of the differential amplifier is to suppress the common mode signal of the two inputs. As shown in Figure 1, assuming that V2 is 5 V and V1 is 3 V, then 4V is the common-mode input. V2 is 1 V higher than the common mode voltage, and V1 is 1 V lower. The difference between the two is 2 V, so the "ideal" gain of R2/R1 is applied to 2 V.If the resistance is not ideal, part of the common-mode voltage will be amplified by the differential amplifier and appear at VOUT as the effective voltage difference between V1 and V2, which cannot be distinguished from the real signal. The ability of the differential amplifier to suppress this part of the voltage is called  Common Mode Rejection  (CMR). This parameter can be expressed as a ratio (CMRR) or converted into decibels (dB).In an article published in 1991, Ramón Pallás-Areny and John Webster pointed out that assuming that the op amp is an ideal op amp, the common mode rejection can be expressed as:Among them, Ad is the gain of the difference amplifier, t is the resistance tolerance. therefore:In the case of unity gain and 1% resistance, CMRR is equal to 50 V/V (or about 34 dB);In the case of 0.1% resistance, CMRR is equal to 500 V/V (or approximately 54 dB);It is even assumed that the operational amplifier is an ideal device with unlimited common-mode rejection.If the common-mode rejection of the operational amplifier is sufficiently high, the total  CMRR is limited by resistance matching. Some low-cost op-amps have a minimum CMRR of 60 dB to 70 dB, making calculations more complicated.III Low Tolerance ResistanceThe first suboptimal design is shown in Figure 2.This design is a low-end current detection application using OP291. R1 to R4 are discrete 0.5% resistors. According to the formula in the article by Pallás-Areny, the optimal CMR is 64 dB.Fortunately, the common-mode voltage is very close to the ground, so CMR is not the main source of error in this application. A current sense resistor with a tolerance of 1% will produce a 1% error, but the initial tolerance can be calibrated or adjusted.However, since the operating range exceeds 80°C, the temperature coefficient of resistance must be considered.Figure 2. Low-end detection with high noise gainFor extremely low shunt resistance values, a 4-pin Kelvin sense resistor should be used. Using a high-precision 0.1 Ω resistor and directly connecting the resistor with a PCB trace of a few tenths of an inch can easily increase 10 mΩ, resulting in an error of more than 10%. But the error will be greater because the temperature coefficient of the copper traces on the PCB exceeds 3000 ppm.The shunt resistance value must be carefully selected. A higher value produces a larger signal. This is a good thing, but the power consumption (I2R) will also increase, possibly up to several watts. With a smaller value (mΩ level), the parasitic resistance of the line and PCB trace may cause a larger error. Generally, Kelvin detection can be used to reduce these errors.We can use a special four-terminal resistor (such as Ohmite LVK series) or optimize the PCB layout to use standard resistors. If the value is extremely small, PCB traces can be used, but this will not be very accurate.Commercial four-terminal resistors (such as Ohmite or  Vishay's products) may cost several dollars or more to provide 0.1% tolerance and extremely low temperature coefficient. A complete error budget analysis can show how to improve accuracy with the minimal cost increase.Regarding the problem of a large offset (31mV) with no current flowing through the sense resistor, it is caused by the "rail-to-rail" op amp being unable to swing all the way to the negative power rail (ground).However, the term "rail-to-rail" can be misleading: the output will be close to the power rail—much closer than the output stage of a classic emitter follower—but never actually reach the power rail. Rail-to-rail operational amplifiers have a minimum output voltage VOL, which is equal to VCE(SAT) or RDS(ON) × ILOAD.If the offset voltage is equal to 1.25 mV and the noise gain is equal to 30, the output is equal to: 1.25 mV × 30 = ±37.5 mV (35 mV due to the presence of VOS and VOL). Depending on the polarity of VOS, the output may be as high as 72.5 mV without load current.If the maximum value of VOS is 30μV and the maximum value of VOL is 8 mV, modern zero-drift amplifiers (such as AD8539) can reduce the total error to the level mainly caused by the sense resistor.IV Another Low-end Detection ApplicationAnother example is shown in Figure 3. This example has low noise gain, but it uses a low precision four-channel op amp with 3 mV offset, 10-μV/°C offset drift, and 79 dB CMR,  And in the range of 0 A to 3.6 A, an accuracy of ±5 mA is required. If a ±0.5% detection resistor is used, the required ±0.14% accuracy cannot be achieved. If a 100 mΩ resistor is used, a ±5 mA current can produce a ±500 μV voltage drop.Unfortunately, the offset voltage of an op amp with temperature is ten times greater than the measured value. Even if VOS is adjusted to zero, a temperature change of 50°C will exhaust the entire error budget. If the noise gain is 13, any change in VOS will be expanded by 13 times. To improve performance, zero-drift operational amplifiers (such as AD8638, ADA4051, or ADA4528), thin-film resistor arrays, and higher-precision sense resistors should be used.Figure 3. Low-end detectionV High Noise GainThe design in Figure 4 is used to measure high-side current, and its noise gain is 250. The maximum VOS rating of the OP07C operational amplifier is 150 μV. The maximum error is 150 μV × 250 = 37.5 mV. To improve performance, and ADA4638 zero-drift operational amplifier is used. The device has a nominal offset voltage of 12.5 μV over the temperature range of -40°C to +125°C.However, due to the high noise gain, the common-mode voltage will be very close to the voltage across the sense resistor. The input voltage range (IVR) of OP07C is 2 V, which means that the input voltage must be at least 2 V below the positive rail. For the ADA4638, IVR = 3 V.Figure 4. High-side current detectionVI Single Capacitor Roll-offThe example in Figure 5 is slightly more complicated. So far, all the equations are for resistance. But it is more accurate than they should take impedance into account. In the case of adding capacitance (whether it is deliberately added capacitance or parasitic capacitance), the AC CMRR depends on the impedance ratio at the target frequency. To roll off the frequency response in this example, you can add a capacitor C2 across the feedback resistor, as you would normally do in an inverting op-amp configuration.Figure 5. Try to create a low pass responseIf you need to match the impedance ratio Z1 = Z3 and Z2 = Z4, you must add capacitor C4. It is easy to buy 0.1% or better resistors on the market, but even 0.5% capacitors cost more than $1. The impedance at very low frequencies may not matter, but capacitance tolerance or a 0.5 pF difference between the two op amp inputs due to PCB layout can cause the AC CMR  to drop by 6 dB at 10 kHz. This is particularly important when using a switching regulator.Single-chip difference amplifiers (such as AD8271, AD8274 or AD8276) have much better AC CMRR performance. Because the two inputs of the operational amplifier are in a controlled environment on the chip, and the price is usually cheaper than a discrete operational amplifier and four precision resistors.VII Capacitance between Input Terminals of Op AmpIn order to roll off the response of the differential amplifier, some designers will try to add a capacitor C1 between the two op amp inputs to form a differential filter, as shown in Figure 6.This is feasible for instrumentation amplifiers, but not feasible for operational amplifiers. VOUT will move up and down through R2, forming a closed loop. At DC, this does not cause any problems, and the circuit behaves as described in Equation 2.As the frequency increases, the reactance of C1 decreases. The feedback into the input of the op amp decreases, causing the gain to increase. Eventually, the op amp will work in an open-loop state because the capacitor shorts the input.Figure 6. Input capacitance reduces high frequency feedbackOn the Bode plot, the open-loop gain of the operational amplifier drops at -20dB/dec, but the noise gain increases at +20dB/dec, forming a -40dB/dec crossover. As we know, it must oscillate. In general, never use capacitors between the inputs of an operational amplifier (except in rare cases, but this blog will not discuss it here).VIII ConclusionWhether it is a discrete or single chip, the four-resistor differential amplifier is widely used. In order to obtain a stable and production-worthy design, the noise gain, input voltage range, impedance ratio, and offset voltage specifications should be carefully considered. FAQWhat is the differential amplifier circuit able to do?Reduce the zero drift What is the differential amplifier circuit often used as?Multi-stage amplifiers What is one of important functions of the differential amplifier?Suppress the common mode signal of the two inputs.

I DescriptionSometimes, if you can use the inexpensive LM386 and use it to make a stereo power amplifier, the effect should be considered ideal. Here, this blog will introduce the methods and experience of using LM386 to make a microcomputer stereo power amplifier.CatalogI DescriptionII Introduction2.1 LM386 schematic2.2 How to use LM386III Installation and commissioningFAQOrdering & QuantityII Introduction2.1 LM386 schematicLM386 is a low-power high-gain power amplifier circuit. Its encapsulation form is shown as in Fig. 1. Figure 1. LM386 PinoutBecause the audio signal amplitude of the "line output" of the sound card is large, it can drive the LM386  and then the speaker. And because it will be interfered by the video signal when playing VCD, it is not good to follow the typical circuit connection. At this time, we need to add some components and debug component values. The schematic diagram of LM386  is shown in Fig. 2. Figure 2. LM386 SchematicLM386 pin functions are as follows:LM386 has two input terminals: non-inverting input terminal 3rd pin and inverting input terminal 2nd pin. The input signal can be input from any end, the other input end is grounded, the input end is connected in parallel with the capacitor C4, the purpose is to filter out the video interference when playing VCD. The value can be increased appropriately, but it can be with or without C4 when playing the CD.Pins 1 and 8 are the gain control terminals, and the gain control network is composed of C2 and W2. The smaller the resistance, the higher the gain. Figure 2 Schematic diagram W2 is more appropriate to adjust the gain to about 150Ω, and the gain is too high to cause self-excitation;Connect a 10μ capacitor to pin 7 to avoid self-excitation when the gain is too high;R2 and C6 form a high-frequency component attenuation circuit to eliminate the "crack" sound from the speaker. Among them, the size of the C6 capacity is adjusted according to the actual effect;A 0.1μ capacitor is connected to the 6th pin to ground to filter and eliminate the static hum of the amplifier;The 5th pin is connected to the coupling capacitor C3. If only one cone speaker is connected to one channel (the author uses a cone speaker with a diameter of 120mm, impedance 8 ohms, and output power of 1W), the C3 capacity cannot exceed 470μ. Otherwise, the speaker will be blocked when playing low music. If the high and low frequency crossover technology is adopted, the C3 capacity can be increased to fully reflect the bass.W1 is used to adjust the output volume, which is especially convenient when playing games or listening to CDs; the working voltage is 10 volts, and a bridge rectifier filter circuit can be made by yourself.2.2 How to use LM386LM386 is an audio power amplifier IC widely used in electronic products and home amateur production. Its typical application circuit is shown in Fig. 3. Figure 3. LM386  CircuitSo, how should we use LM386 correctly?1. Self-excited howling caused by the excessive input signal. For the howling caused by the excessive input signal, a resistance-capacitance network can be added between the 1 and 8 pins of LM386,  In batch application, the resistance of R can be determined by experiments, or R can be replaced by a trimming potentiometer W. If the signal is still too strong, LM386 pins 1 and 8 can be suspended.2. High-frequency self-excitation. The principle of the anti-high frequency self-excitation circuit is shown in Figure 4. For howling caused by high-frequency self-excitation, a 4700pF~0.22μF ceramic capacitor can be connected between the signal input terminal and the ground, and a 1000~4700pF capacitor can be connected between the 8th pin and the ground. When making single-ended input, the idle input terminal should not be grounded. Figure 4. LM386  Circuit3. Low-frequency self-excitation. For howling caused by low-frequency self-excitation, you can try to connect a 68~22kΩ resistor between the input terminal and the ground, increase the filter capacitor of pin 8 to 1000μF, and make the LM386 as close as possible to the output terminal of the power supply when making the printed board.4. When using other brand products (such as GL386, KA386, etc.), some ICs will affect the sensitivity of high-frequency audio. A 0.1μF ceramic capacitor can be connected between its 7th pin and ground, and a 0.1μF ceramic capacitor can be connected between the 4th and 6th pins (note: different from the 8th pin to ground).III Installation and commissioningAccording to the schematic diagram shown in Figure 2, we can make two identical power amplifier circuits, which are combined to form a stereo power amplifier.Because there are few components, it is better to use double-core shielded wires without making printed circuit boards. Then, connect the stereo plug to the two amplifiers, and use the shield wire as the ground wire.Do not connect the amplifier to the sound card after soldering. At this time, we should first check that the welding is correct and then turn on the power, and then tap the two input ends of the stereo plug with metal tweezers. If the two speakers can knock out normally, it indicates that the amplifier is working properly. At this time, after turning off the power of the amplifier and the microcomputer, we can connect it to the sound card.The connection method is to insert the stereo plug into the line output jack (LineOut) of the sound card.Finally, it is emphasized that you should avoid unplugging and plugging the stereo plug when the power is on (microcomputer or amplifier), or welding the circuit when the amplifier is connected to the sound card, so as not to damage the computer.FAQWhat is LM386?Low-power high-gain power amplifier circuitHow many input terminals does LM386 have?Non-inverting input terminal 3th pin and inverting input terminal 2th pin.How does an LM386 work?The Lm386 integrated chip is a low power audio frequency amplifier, which uses low level power supply like batteries in electronic circuits. It is designed as 8 pin mini DIP package. This provides voltage amplification of 20. By using external parts voltage gain can be raised up to 200.Is lm386 an op amp?The LM386 is a type of operational amplifier (Op-Amp). ... In an amplifier circuit, the LM386 takes an audio input signal and increases its potential anywhere from 20 to 200 times. That amplification is what's known as the voltage gain.What is lm386 IC?The LM386 is an integrated circuit containing a low voltage audio power amplifier. It is suitable for battery-powered devices such as radios, guitar amplifiers, and hobby electronics projects.How do you calculate lm386 gain?Voltage Gain Analysis:Without any external components, it has a gain of Gv = 2x15K/(150+1350) = 20 (26 dB).With a capacitor (or shortcutting) between pins 1 and 8 , it has a gain of Gv = 2x15K/150 =200 (46dB).Which IC is used in audio amplifier?The IC LM386 is a low-power audio amplifier, and it utilizes low power supply like batteries in electrical and electronic circuits. This IC is available in the package of mini 8-pin DIP.What are some projects that use the LM386 audio amplifier circuit?LM 386 is an integrated class AB amp and is good for beginners small audio amplifier applications…for example in a RF receiver,small Stereo system,cheap low voltage amplifier etc…drawbacks is that it cannot handle much power and hence creates distortion when you crank up the volume too much.. So other ICs are used in practical.How to make an LM386 audio amplifier circuit?