The Kynix Components

DescriptionThe CD405xB analog multiplexers and demultiplexers are digitally-controlled analog switches having low ON impedance and very low OFF leakage current. These multiplexer circuits dissipate extremely low quiescent power over the full VDD – VSS and VDD – VEE supply voltage ranges, independent of the logic state of the control signals.The CD4051B is a single 8-Channel multiplexer having three binary control inputs, A, B, and C, and an inhibit input. The three binary signals select 1 of 8 channels to be turned on, and connect one of the 8 inputs to the output.CatalogDescriptionPinout Configuration and FunctionCD4051 Block DiagramDocuments and MediaFeaturesApplicationCD4051 Typical Application CircuitsOrdering & QuantityPinout Configuration and FunctionCD4051 Block DiagramThe logic diagram of CD4051 is composed of three parts: logic level conversion circuit, 8 select 1 decoding circuit and 8 CMOS switch units. A, B and C are 3-bit binary address input terminals, and 8 combinations of 3-bit binary can be used for selection 8 channels; INH is the address input prohibition terminal, when it is high, the address input terminal is invalid, that is, no channel is strobed. The input levels of A, B, C and INH are compatible with TTL. CD4051 has 8 input\output terminals, 1 output/input terminal, digital circuit power supply +E and -E1, analog circuit power supply +E and -E2. The main function of the logic level conversion circuit is to input the address A, B , C and address input inhibit terminal INH input TTL logic level is converted into CMOS level, so that the switch unit can be controlled by TTL level. The main function of the 8-to-1 address decoding circuit is to convert the address input signal from the logic level conversion circuit into the corresponding switch unit strobe signal and turn on the corresponding switch unit.Documents and MediaDatasheetCD405xB CMOS Single 8-Channel Analog Multiplexer/Demultiplexer with Logic-Level Conversion datasheet (Rev. I)FeaturesWide Range of Digital and Analog Signal LevelsDigital: 3 V to 20 VAnalog: ≤ 20 VP-PLow ON Resistance, 125 Ω (Typical) Over 15 VP-P Signal Input Range for VDD – VEE = 18 VHigh OFF Resistance, Channel Leakage of±100 pA (Typical) at VDD – VEE = 18 VLogic-Level Conversion for Digital Addressing Signals of 3 V to 20 V (VDD – VSS = 3 V to 20 V) to Switch Analog Signals to 20 VP-P (VDD – VEE = 20 V) Matched Switch Characteristics, rON = 5 Ω (Typical) for VDD – VEE = 15 V Very Low Quiescent Power Dissipation Under All Digital-Control Input and Supply Conditions, 0.2 µW (Typical) atVDD – VSS = VDD – VEE = 10 VBinary Address Decoding on Chip5 V, 10 V, and 15 V Parametric Ratings100% Tested for Quiescent Current at 20 VMaximum Input Current of 1 µA at 18 V Over Full Package Temperature Range, 100 nA at 18 V and 25°CBreak-Before-Make Switching Eliminates Channel OverlapApplicationAnalog and Digital Multiplexing and DemultiplexingA/D and D/A ConversionSignal GatingFactory AutomationTelevisionsAppliancesConsumer AudioProgrammable Logic CircuitsSensorsCD4051 Typical Application Circuits1.CD4051, CH3130 multi-channel demodulator circuit diagramThis circuit is mainly composed of 8-channel analog switch CD4051 and voltage follower CH3130, etc. The input signal of the prohibition terminal "INH" of analog switch CD4051 is used to control the gating of voltage follower CH3130, thereby perform demodulation to multiple analog signals.2. CD4051 constructs 32-channel circuitBecause the CD4051 has only eight input ports, four CD4051s are needed to build a 32-way multiplexer, labeled INH1, INH2, INH3, and INH4.The 32-way multiplexer should have 5 control ports, of which the first three are the input ports of CD4051 and the last two are control ports. (Because CD4051 has three input ports), label them as D1, D2, D3, D4, D5 (00000—11111, 00000 channel 0, 11111 channel 31).The basic idea is to realize the choice of 32 channel ports (0-7, 8-15, 16-23, 24-31) by selecting 4 CD4051s. If you choose the third CD4051, you can choose 16-23 (10000-10111) channel port.However, the selection of CD4051 is achieved by controlling the INH level of each CD4051. For example, if you want to turn on the third CD4051, make its INH high (at this time D5=1, D4=0, then INH3=D5&! D4). Therefore, the choice of INH is achieved by controlling the logical relationship between D5 and D4. Where INH1=! D5&! D4;INH2=! D5&D4;INH3=D5&! D4;INH4=D5&D4. 

UC3845 is a high-performance fixed-frequency current-mode controller, designed for offline and DC-to-DC converter applications, providing designers with a cost-effective solution that requires minimal external components.  These integrated circuits have a fine-tunable oscillator, precise duty cycle control, temperature compensation reference, high gain error amplifier, current sampling comparator and high current totem pole output. It is an ideal devices for driving power MOSFETs.CatalogUC3845 PinoutUC3845 Functional Block DiagramUC3845 FeaturesUC3845 EquivalentsUC3845 ApplicationsUC3845 PackageUC3845 ManufacturerComponent DatasheetOrdering & Quantity UC3845 PinoutPin Functions:PinTypeDescription NameSOIC, CDIP, PDIP (8)SOIC, CFP (14)LCCC (20)COMP112OError amplifier compensation pin. Connect external compensation components to this pin to modify the error amplifier output. The error amplifier is internally current-limited so the user can command zero duty cycle by externally forcing COMP to GROUND.GROUND5913GAnalog ground. For device packages without PWRGND, GROUND functions as both power ground and analog ground.PWRGND-812GPower ground. For device packages without PWRGND, GROUND functions as both power ground and analog groundISENSE357IPrimary-side current sense pin. Connect to current sensing resistor. The PWM uses this signal to terminate the OUTPUT switch conduction. A voltage ramp can be applied to this pin to run the device with a voltage-mode control configuration.NC-2, 4, 6, 131, 3, 4, 6, 8, 9, 11, 14, 16, 19-Do not connectOUTPUT61015OOUTPUT is the gate drive for the external MOSFET. OUTPUT is the output of the on-chip driver stage intended to directly drive a MOSFET. Peak currents of up to 1 A are sourced and sunk by this pin. OUTPUT is actively held low when VCC is below the turnon threshold.RT/CT4710I/OFixed frequency oscillator set point. Connect timing resistor, RRT, to VREF and timing capacitor, CCT, to GROUND from this pin to set the switching frequency. For best performance, keep the timing capacitor lead to the device GROUND as short and direct as possible. If possible, use separate ground traces for the timing capacitor and all other functions. The frequency of the oscillator can be estimated with the following equations:fosc=1.72/RRT × CCT                                                          (1) where fosc is in Hertz, RRT is in Ohms and CCT is in Farads. Never use a timing resistor less than 5 kΩ. The frequency of the OUTPUT gate drive of the UCx842 and UCx843, fSW, is equal to fOSC at up to 100% duty cycle; the frequency of the UCx844 and UCx845 is equal to half of the fOSC frequency at up to 50% duty cycle.VC-1117IBias supply input for the output gate drive. For PWM controllers that do not have this pin, the gate driver is biased from the VCC pin. VC must have a bypass capacitor at least 10 times greater than the gate capacitance of the main switching FET used in the design.VCC71218IAnalog controller bias input that provides power to the device. Total VCC current is the sum of the quiescent VCC current and the average OUTPUT current. Knowing the switching frequency and the MOSFET gate charge, Qg, the average OUTPUT current can be calculated from:IOUTPUT = Qg × fSW                                                          (2) A bypass capacitor, typically 0.1 µF, connected directly to GROUND with minimal trace length, is required on this pin. An additional bypass capacitor at least 10 times greater than the gate capacitance of the main switching FET used in the design is also required on VCC.VFB235IInverting input to the internal error amplifier. VFB is used to control the power converter voltage-feedback loop for stability.VREF81420O5-V reference voltage. VREF is used to provide charging current to the oscillator timing capacitor through the timing resistor. It is important for reference stability that VREF is bypassed to GROUND with a ceramic capacitor connected as close to the pin as possible. A minimum value of 0.1-µF ceramic is required. Additional VREF bypassing is required for external loads on VREF.UC3845 Functional Block DiagramUCx844 and UCx845 Block Diagram, ToggleUC3845 FeaturesOptimized for off-line and DC-to-DC convertersLow start-up current (< 1 mA)Automatic feedforward compensationPulse-by-pulse current limitingEnhanced load-response characteristicsUndervoltage lockout with hysteresisDouble-pulse suppressionHigh-current totem-pole outputInternally trimmed bandgap referenceUp to 500-kHz operationError amplifier with low output resistanceUC3845 EquivalentsUC3845 ApplicationsSwitching regulators of any polarityTransformer-coupled DC-DC convertersUC3845 PackageUC3845 ManufacturerTexas Instruments Incorporated designs and manufactures analog technologies, digital signal processing (DSP) and microcontroller (MCU) semiconductors. TI is a leader in semiconductor solutions for analog and digital embedded and applications processing. A global semiconductor company, TI innovates through design, sales and manufacturing operations in more than 30 countries.Component DatasheetUC3845 Datasheet

IntroductionLM339 (Quad differential comparator) consist of four independent voltage comparators. It is a common integrated circuit and is mainly used in high-voltage digital logic gate circuits. Using LM339 can easily form various voltage comparator circuits and oscillator circuits.CatalogIntroductionCatalogI Circuit of Single Limit ComparatorII Overheat Detection and Protection CircuitIII Hysteresis ComparatorIV Over-voltage Detection CircuitV Double Limit ComparatorVI Using LM339 to form an OscillatorFAQOrdering & QuantityI Circuit of Single Limit Comparator Figure (a) shows a basic single limit comparator. Add the input signal UIN (i.e. voltage to be compared) to the in-phase input terminal, and connect a reference voltage Ur at the anti-phase input terminal. When the input voltage Uin > Ur, the output is high level UOH. Figure (b) shows its transmission characteristics.Figure 1. Circuit of Single Limit ComparatorII Overheat Detection and Protection CircuitIt is powered by a single power supply. A fixed reference voltage is added to the anti-phase input terminal of 1/4LM339, and its value depends on R1 and R2. UR=R2/（R1+R2）*UCC. The voltage at the in-phase terminal is equal to the voltage drop of the thermistor RT. When the temperature inside the machine is below the set value, the "+" terminal voltage is greater than the "-" terminal voltage, and Uo is a high potential. When the temperature rises above the set value, the "-" terminal voltage is greater than the "+" terminal, and the Uo output is at zero potential, which causes the protection circuit to operate. Adjusting the value of R1 can change the threshold voltage, which sets the temperature value.Figure 2. Overheat Detection and Protection CircuitIII Hysteresis ComparatorThe hysteresis comparator can also be regarded as a single limit comparator with positive feedback. In the single limit comparator described above, if the input signal Uin has slight interference near the threshold, the output voltage will produce corresponding undulation. This shortcoming can be overcome by introducing positive feedback into the circuit..Figure (a) shows a hysteresis comparator. The familiar Schmidt circuit is a comparator with hysteresis. Figure (b) shows the transmission characteristics of the hysteresis comparator.Figure 3. Hysteresis ComparatorIt is not difficult to see that once the output state is changed, the output voltage will be stable as long as the interference near the jump voltage value does not exceed the value of Δ U. Accordingly, it comes to a reduction in resolution. For the hysteresis comparator, it can't distinguish two input voltages whose difference is less than ΔU. The hysteresis comparator with positive feedback can accelerate the response speed of the comparator, which is one of its advantages. In addition, since the positive feedback added by the hysteresis comparator is very strong and much stronger than the parasitic coupling in the circuit, the hysteric comparator can also avoid the self-oscillation caused by the parasitic coupling of the circuit.IV Over-voltage Detection CircuitFigure 4 shows the part of over-voltage detection circuit in an induction cooker circuit. When the grid voltage is normal, 1 / 4lm339 u42.8v, the comparator turns over. The output is 0V and BG1 is cut off. The voltage of U5 is completely determined by the partial voltage value of R1 and R2, which is 2.7V. It makes U4 larger than U5, which makes the state after overturning extremely stable and avoids the instability caused by the small fluctuation of grid voltage near the over-voltage point. Due to certain hysteresis, after overvoltage protection, the induction cooker starts to work again when the grid voltage drops to 242-5 = 237v and U4 < U3.Figure 4. Over-voltage Detection CircuitV Double Limit Comparator The circuit in Figure 5 consists of two LM339 to form a window comparator. When the compared signal voltage Uin is between the threshold voltages (UR1<Uin<UR2), the output is high potential (UO=UOH). When Uin is not between the threshold potential range, (Uin>UR2 or Uin<UR1) the output is low potential (UO=UOL), and the window voltage ΔU=UR2-UR1. It can be used to judge whether the input signal potential is between the specified threshold potential.Figure 5. Double Limit ComparatorVI Using LM339 to form an OscillatorFigure 6 shows the circuit of an audio square wave oscillator composed of 1/4LM339. Changing C1 can change the frequency of the output square wave. In this circuit, when C1=0.1uF, f=53Hz; when C1=0.01uF, f=530Hz; when C1=0.001uF, f=5300Hz.LM339 can also form a high-voltage digital logic gate circuit, and can directly interface with TTL and CMOS circuits.Figure 6. LM339 OscillatorFAQWhat is LM339?LM339 is a voltage comparator IC from LMx39x series and is manufactured by many industries. The devices consist of four independent voltage comparators that are designed to operate from a single power supply.What 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.How does LM339 comparator work?The LM339 is a quad op amp comparator. A comparator works by a simple concept. Each op amp of a comparator has 2 inputs, a inverting input and a noninverting input. If the inverting input voltage is greater than the noninverting input, then the output is drawn to ground.What is comparator ic?A comparator is an electronic circuit, which compares the two inputs that are applied to it and produces an output. The output value of the comparator indicates which of the inputs is greater or lesser. Please note that comparator falls under non-linear applications of ICs.What is the replacement for LM339?LM311, LM324, LM397, LM139, LM239, LM2901What is a comparator circuit?A comparator circuit compares two voltages and outputs either a 1 (the voltage at the plus side; VDD in the illustration) or a 0 (the voltage at the negative side) to indicate which is larger. Comparators are often used, for example, to check whether an input has reached some predetermined value.What is the use of LM339?LM339 is used in applications where a comparison between two voltage signals is required. In addition with four of those comparators on board the device can compare four pairs of voltage signals at a time which comes in handy in some applications.

IntroductionThe CD4066 is a quad bilateral switch which can be applied for switching of analog signals and digital signals. It consists of four independent analog switches, each with three terminals: input, output and control. When the control terminal is applied with high power level, the switch is on. When the control terminal is added with low power level, the switch is closed. The input terminal and output terminal can be used interchangeably. This configuration eliminates the variation of the switch-transistor threshold voltage with input signal and, thus, keeps the on-state resistance low over the full operating-signal range. The advantages over single-channel switches include peak input-signal voltage swings equal to the full supply voltage and more constant on-state impedance over the input-signal range. This article introduces two application examples of CD4066 analog switch.CatalogIntroductionCatalogI Track-and-Hold Circuit of SignalII Interchanging Display Circuit of Four Ways of Electronic SignalFAQOrdering & QuantityI Track-and-Hold Circuit of SignalFigure 1. Track-and-Hold Circuit of SignalThe analog signal Ui is from the in-phase input of the operational amplifier. When the control terminal of the analog switch is at high level, the analog switch is on, and the capacitor C is charged to Ui. This process is called the sampling of the input signal. When the sampling is over, the control terminal of the analog switch is low level and the analog switch is off. Because the resistance is as high as 100M when the analog switch is off, and the input impedance of operational amplifier A2 is also very high, the sampling signal can be maintained on the capacitor C.II Interchanging Display Circuit of Four Ways of Electronic SignalA general single line oscilloscope can only display one continuous signal. But this device can display four continuous signals simultaneously in a single line oscilloscope. It is very convenient to compare the time relation of different signals.Figure 2. Interchanging Display Circuit of Four Ways of Electronic SignalFigure 2 is the circuit diagram of the device. It uses a CD4017 counter and oscillator to form a four-beat circuit to control the four analog switches in two CD4066. Adjustable DC level and one input signal are added respectively on each pair of analog switches. When the control end of the analog switch is high level 1, the analog switch is on. The DC level and input signal are sent to the y-axis input end of the oscilloscope. Because the four signals correspond to different DC levels, the four signals display separately on the oscilloscope. Although the four pairs of analog switches are controlled by the counter's Q0, Q1, Q2, Q3 output terminal, the flicker of the waveform is small due to the high oscillation frequency of the oscillator.FAQWhat is CD4066?The CD4066 is a Quad Bilateral Switch IC, that is, it has four switches which can be controlled individual using a control pin. These switches can conduct in both the directions making it bilateral, it is commonly used for multiplexing analog or digital signals.How to use CD4066?The CD4066 IC consists of four switches. It can switch analog signals through digital control. An analog signal is applied at the input of the switch. If a HIGH or 1 value is fed into the control input, the analog signal will be passed from input to the output of a switch.How CD4066 work?The 4066 really functions as an analog switch. The 4066 is an IC composed of switches which are designed to switch analog signals via digital control. ... The 4066 is a quad bilateral switch circuit, meaning that is composed of 4 switches. Each switch has a single input and a single output terminal.What are the applications of CD4066？The CD4066 is a bi-directional analog switching IC similar to CD4016, it is commonly used in multiplexing applications; it can also be used to isolate signals. The switch is bilateral and hence can be used for both digital and analog signals.What's the difference between CD4016 and CD4066？The major difference between both is that CD4066 has very low internal resistance, according to the datasheet it can only 5Ω of on-state resistance as compared with 200Ω of CD4016 IC.

AD620 is a low cost, high accuracy instrumentation amplifier that requires only one external resistor to set gains of 1 to 10,000. This blog covers AD620 amplifier pinout, datasheet, equivalent, features, and other information on how to use and where to use this device.CatalogAD620 IntroductionAD620 PinoutAD620 Basic ParametersAD620 FeaturesAD620 ApplicationsWhere to use AD620 amplifier?How to use AD620 amplifier?AD620 PackageAD620 Application CircuitAD620 Working PrincipleAD620 Alternative ModelsAD620 ManufacturerFAQOrdering & QuantityAD620 IntroductionADI’s AD620 comes in 8-lead SOIC and DIP packages and are low-cost, high-accuracy instrumentation amplifiers that, with an external resistor, allow the user to set gains of 1 to 10,000. The small footprint design and low power consumption (only 1.3 mA (maximum) supply current) make it a good fit for portable or remote applications that require a battery. The AD620, with its high accuracy of 40 ppm (maximum) nonlinearity, low offset voltage of 50 µV (maximum), and offset drift of 0.6 µV/°C (maximum), is ideal for use in precision data acquisition systems such as weigh scales and transducer interfaces. Furthermore, the low noise, low input bias current, and low power of the AD620 make it well suited for medical applications such as ECG and noninvasive blood pressure monitors. The low input bias current of 1.0 nA (maximum) is made possible with the use of Superϐeta processing in the input stage. The AD620 works well as a preamplifier due to its low input voltage noise of 9 nV/√Hz at 1 kHz, 0.28 μV p-p in the 0.1 Hz to 10 Hz band, and 0.1 pA/√Hz input current noise. Also, the AD620 is well suited for multiplexed applications with its settling time of 15 μs to 0.01%, and its cost is low enough to enable designs with one in-amp per channel.AD620 PinoutThe datasheet provided above is for your reference, so that you can understand the physical dimensions of all packages in more detail. The configuration of all 8 pins and the function of each pin are as follows: The function of all 8 pins are as follows:Pin NumberPin NameDescription1Gain (Rg)Inverting Gain Terminal connected to a resistor to set gain value2Inverting Input (IN-)The Inverting input pin of the Op-Amp3Non- Inverting Input (IN-)The Non - Inverting Input Pin of Amplifier4Power (-Vs)Negative supply terminal5ReferenceOutput reference input. Normally connected to common6OutputAmplifier output pin7Power (+Vs)Positive supply terminal8Gain (Rg)Non - Inverting Gain Terminal connected to resistor to set gain valueAD620 Basic ParametersParametersAD620AAD620BAD620SGain Range10,00010,00010,000Gain Error G=1 (%) 0.100.020.10Gain Error G=1000 (%)0.70.50.7Input Offset (µV)12550125Input Bias current (nA)2.01.02.0Input Offset Current (nA)1.00.51.0Input Voltage Range (V)+ -1.2+ -1.2+ -1.2Input offset current (nA)20050500Input Impedance Differential Common Mode (GΩ_pF)10II210II210II2Common Mode Rejection Ratio G=1 (dB)909090Common Mode Rejection Ratio G=1000 (dB)130130130Slew Rate (V/µs)1.21.21.2Small Signal -3dB Bandwidth G=1 (kHz)100010001000Small Signal -3dB Bandwidth G=1000 (kHz)121212Settling Time to 0.01% G= 1-100 (µs)151515Settling Time to 0.01% G= 1000 (µs)150150150Input Voltage Noise (nV/ Hz)131313Output Voltage Noise (nV/ Hz)100100100Reference Input Resistance (kΩ)202020Reference Input Current (µA)606060Reference Input Voltage Range (V)+ -1.6+ -1.6+ -1.6Output Short Circuit DurationIndefiniteIndefiniteIndefiniteLead Temperature Range for 10sec soldering (°C)300300300Operating Temperature Range (°C)-40 to +85-40 to +85-55 to +125AD620 FeaturesEASY TO USE　　Gain Set with One External Resistor　　(Gain Range 1 to 10,000)　　Wide Power Supply Range (±2.3 V to ±18 V)　　Higher Performance than Three　　Op Amp IA Designs　　Available in 8-Lead DIP and SOIC Packaging　　Low Power, 1.3 mA max SupplyLOW NOISE　　9 nV/√Hz, @ 1 kHz, Input Voltage Noise　　0.28 µV p-p Noise (0.1 Hz to 10 Hz)EXCELLENT DC PERFORMANCE (B GRADE)　　50 µV max, Input Offset Voltage　　0.6 µV/°C max, Input Offset Drift　　1.0 nA max, Input Bias Current　　100 dB min Common-Mode　　Rejection Ratio (G = 10)EXCELLENT AC SPECIFICATIONS　　120 kHz Bandwidth (G = 100)　　15 µs Settling Time to 0.01%AD620 ApplicationsWeigh scalesECG and medical instrumentationTransducer interfaceData acquisition systemsIndustrial process controlsBattery-powered and portable equipmentWhere to use AD620 amplifier?The AD620, with its high accuracy of 40 ppm maximum nonlinearity, low offset voltage of 50 μV max, and offset drift of 0.6 μV/°C max, is ideal for use in precision data acquisition systems, such as weigh scales and transducer interfaces. Furthermore, the low noise, low input bias current, and low power of the AD620 make it well suited for medical applications, such as ECG and non-invasive blood pressure monitors.How to use AD620 amplifier?The AD620 only requires a resistor to set its gain value and can therefore be easily set up. The most basic commonly used circuit for AD620 is shown below.The IC is powered by pin 7 and pin 4 is connected to the ground. Here I used a single supply of +5V. The non-inverting pin (pin 2) and the inverting pin (pin 3) are connected to the signal to be amplified or compared on the basis of the Op-Amp application. The reference pin (pin 5) is normally grounded along with pin 4, the reference pin is used to direct the output to the voltage when the difference voltage between the inverter and the non-inverter pin is 0V. The Gain of the Op-Amp can be set simply by connecting the correct resistance value to the pin +Rg (pin 8) and the pin –Rg (pin 1). Here I have connected a resistor with a value of 500, which will set the Op-Amp to a gain value of 100. The formulas used to calculate the gain value from R have been given below.G = (49.4 k/RG) + 1AD620 PackageAD620 Application CircuitAD620 Working PrincipleThe AD620 is a monolithic instrumentation amplifier based on a modification of the classic three op amp approach. Absolute value trimming allows the user to program gain accurately (to 0.15% at G = 100) with only one resistor. Monolithic construction and laser wafer trimming allow the tight matching and tracking of circuit components, thus ensuring the high level of performance inherent in this circuit. The input transistors Q1 and Q2 provide a single differentialpair bipolar input for high precision (Figure 36), yet offer 10× lower input bias current thanks to Superϐeta processing. Feedback through the Q1-A1-R1 loop and the Q2-A2-R2 loop maintains constant collector current of the input devices Q1 and Q2, thereby impressing the input voltage across the external gain setting resistor RG. This creates a differential gain from the inputs to the A1/A2 outputs given by G = (R1 + R2)/RG + 1. The unity-gain subtractor, A3, removes any common-mode signal, yielding a single-ended output referred to the REF pin potential. The value of RG also determines the transconductance of the preamp stage. As RG is reduced for larger gains, the transconductance increases asymptotically to that of the input transistors. This has three important advantages: (a) Open-loop gain is boosted for increasing programmed gain, thus reducing gain related errors. (b) The gain-bandwidth product (determined by C1 and C2 and the preamp transconductance) increases with programmed gain, thus optimizing frequency response. (c) The input voltage noise is reduced to a value of 9 nV/√Hz, determined mainly by the collector current and base resistance of the input devices. The internal gain resistors, R1 and R2, are trimmed to an absolute value of 24.7 kΩ, allowing the gain to be programmed accurately with a single external resistor. The gain equation is then AD620 Alternative ModelsAD8422Higher BW at 1/3 the power, with RRO and OVP (same pinout as AD8221)AD620 ManufacturerAnalog Devices (NASDAQ: ADI) is a world leader in the design, manufacture, and marketing of a broad portfolio of high performance analog, mixed-signal, and digital signal processing (DSP) integrated circuits (ICs) used in virtually all types of electronic equipment. Since established in 1965, ADI have focused on solving the engineering challenges associated with signal processing in electronic equipment. ADI currently produce a wide range of innovative products—including data converters, amplifiers and linear products, radio frequency (RF) ICs, power management products, sensors based on microelectromechanical systems (MEMS) technology and other sensors, and processing products, including DSP and other processors—that are designed to meet the needs of our broad base of customers.Component DatasheetAD620 DatasheetFAQWhat is AD620?AD620 is a low-cost, high-precision instrumentation amplifier. It only requires an external resistor to set the gain. The gain range is 1 to 10,000.Can I change AD620 to AD623 when making MCU products?Both AD620 and AD623 are single instrumentation amplifiers, and the pin arrangement is exactly the same.The main difference is: AD620 must use positive and negative power supplies, AD623 can be a positive and negative power supply or a single power supply.If the original board is AD620, you can replace it with 623; if the original board is AD623, you may not be able to replace it with 620 (it depends on whether the power supply of the original board circuit is dual power supply or single power supply).After replacing AD620 and AD623 in single-chip products, the program can work normally without modification.What is the difference between AD620BR and AD620AN?Their packages are different.What is the output resistance of AD620? How to adjust it?AD620 is a kind of low power consumption instrument amplifier, its output resistance is about 10K, this is the inherent characteristic of this chip, generally it is difficult to adjust.If you have requirements for output resistance, you can generally use an external circuit to solve it.Is AD620 a positive phase amplification or a reverse phase amplification?AD620 is an instrument amplifier, the output voltage is [(Vin+)-(Vin-)]*gain.If the desired signal is (Vin+)-(Vin-), the gain is positive, which is equivalent to positive amplification.Conversely, if the desired signal is (Vin-)-(Vin+), the gain is equivalent to negative, which is equivalent to reverse amplification.What is an instrumentation amplifier?Instrumentation amplifier, an improvement of the differential amplifier, has an input buffer, does not require input impedance matching, so that the amplifier is suitable for measurement and electronic instruments

This text analyzes the advantages of AD590, and uses the energy-saving temperature and humidity control system as an example to introduce the application of using AD590 to measure two-point temperature difference circuit. AD590 is a current output type two-end temperature sensor made by AD company using the relationship between PN junction forward current and temperature. Because the device has good linear characteristics and interchangeability, it has high measurement accuracy and has the characteristics of eliminating power fluctuations. CatalogI. AD590 Advantages and FeaturesII. Celsius Temperature Measurement CircuitIII. Temperature Difference Measurement Circuit and Its Application3.1 Circuit and Principle Analysis3.2 Application Examples3.3. Measurement of the Lowest Temperature Value at Point N3.4. Measurement of Average Temperature at Point NIV. ConclusionFAQOrdering & QuantityI. AD590 Advantages and FeaturesAD590 type current output integrated temperature sensor, the domestic similar product model is SG590. In practice, the corresponding temperature value can be obtained by measuring the current. The suffix of AD590 is represented by I, j, K, L, M, which essentially refers to different characteristics and different measurement temperature ranges. Its advantages and characteristics are as follows:(1) Linear output current: 1 µA/K(2) Wide temperature range: -55°C to +150°C(3) Ceramic sensor package compatible with probe(4) Two-terminal device: voltage input/current output(5) Laser adjusted to ±0.5°C, calibration accuracy (AD590M)(6) Excellent linearity: full scale range ±0.3°C (AD590M)(7) Wide power supply voltage range: 4 V to 30 V(8) The sensor is insulated from the housing(9) Low costII. Celsius Temperature Measurement CircuitAD590 is a current output integrated temperature sensor. When designing a temperature measurement circuit, the current must be converted into a voltage. For every 1K increase in temperature, the current increases by l µA. The design of the Celsius temperature measurement circuit must complete two tasks: one is to convert the current output by the AD590 into a voltage signal, that is, the current is converted into a voltage circuit. The second is to convert the thermodynamic temperature into Celsius, that is, the absolute temperature is converted to Celsius. The working principle of the Celsius temperature measurement circuit is shown in Figure 1. According to the characteristics of AD590, for every lK thermodynamic temperature increased, the current increases by luA, when the load resistance is 10KΩ, the voltage drop on this resistance is 10mV.  Among them, AD590, potentiometers RPl and R1, and operational amplifier A1 form a current-to-voltage conversion circuit. A1 is connected in the form of a voltage follower, mainly to increase the input resistance of the signal. The operational amplifier A2 is the core device that converts absolute temperature to Celsius. Its conversion principle is that zero Celsius corresponds to 273K thermodynamics. Therefore, the reference voltage must be set to convert thermodynamics to Celsius humidity. The value is 2.73V corresponding to zero Celsius. The realization method is to input a constant voltage to the end of the same name of A2. The constant voltage is provided by the current limiting resistor R2 and the Zener tube. The constant voltage selection Zener tube model is CW385 with a value of 1.235V. A2 amplifies this voltage to 2.73 v, RP2 is to adjust the gain of A2 operational amplifier. Through the conversion circuit, the voltage at the output terminals of A1 and A2 is the voltage value proportional to the temperature in degrees Celsius, that is, the voltage value corresponding to 100mV per degree Celsius. Special note: When debugging, put the integrated temperature sensor AD590 in the zero-degree ice water solution, first adjust the RPl potentiometer to make the A1 operational amplifier output 2.73V, and then adjust the RP2 potentiometer to make the A2 operational amplifier output 2.73V, Therefore, the output voltage of the temperature measurement circuit is 0V at zero degrees Celsius. The changing law is that every degree Celsius corresponds to an output voltage of 10mV. Figure 1. Celsius temperature measurement circuit III. Temperature Difference Measurement Circuit and Its Application3.1 Circuit and Principle AnalysisFigure 2 is a circuit that uses two AD590s to measure the temperature difference between two points. In the case of feedback resistance of 100kW, set the temperature at 1# and 2# AD590 as t1(℃) and t2(℃) respectively, then the output voltage is (t1-t2)100mV/℃. The potentiometer R2 in the picture is used for zero adjustment. Potentiometer R4 is used to adjust the gain of the op amp LF355.Figure 2. Circuit for measuring temperature difference between two pointsFrom Kirchhoff’s current law: I+I2=I1+I3+I4 (1)Known from the characteristics of the operational amplifier: I3=0 (2)(3)adjust zero potentiometer R2 so that: I4=0 (4)From (1), (2), (4), we can get: I=I1-I2Setup: R4=90kWthen: Vo = I(R3+R4) = (I1-I2) (R3+R4) =(t1-t2)100mV/℃ (5)Among them, (t1-t2) is the temperature difference, the unit is °C.Knowing from formula (5), changing the value of (R3+R4) can change the size of VO. 3.2 Application ExamplesTake a certain energy-saving medicinal material warehouse temperature and humidity control system as an example, if the warehouse temperature is required to be lower than T℃, the relative humidity is lower than A1B1%RH. The two control modes adopted are as follows: Control mode 1: When the relative humidity in the warehouse is higher than A1B1%RH and the temperature outside the warehouse is lower than T℃, ventilation inside and outside the warehouse is performed. This method uses the difference in humidity inside and outside the warehouse to exchange air to meet the requirements of dehumidification in the warehouse. Its advantages are high efficiency, energy saving, and money saving.  However, this method is strictly controlled. First of all, the relative humidity outside the warehouse should be lower than that in the warehouse, and the difference between them must be greater than A2B2%RH, so as to effectively ensure timely dehumidification inside the warehouse. Secondly, the temperature difference between the inside and outside of the warehouse should be less than △T℃. This is because if ventilation is performed when the temperature outside the warehouse is much higher than the temperature inside the warehouse, the hot air entering the warehouse area will encounter cold air, which will cause condensation on the surface of the medicines and equipment, then affects the their quality. Conversely, if ventilation is carried out when the temperature inside the warehouse is much higher than the temperature outside the warehouse, cold air will also condense on the surface of the medicine equipment after entering the warehouse. In addition, the outside temperature cannot be close to T°C. This is because if ventilation is performed when the temperature outside the storage is close to T°C, the temperature of the closed storage is likely to rise, thereby exceeding the upper temperature limit T°C. Control mode 2: When the temperature is higher than T℃ or the humidity is higher than A1B1%RH, but the first condition is not met, the refrigerating and air-conditioning unit is turned on to cool and dehumidify in the warehouse. In order to avoid the phenomenon of condensation on the surface of medicines and equipment due to the excessive temperature difference between the inside and outside of the warehouse, the accuracy of the system temperature difference must be strictly controlled. The traditional method of measuring the temperature difference is to process the temperature of the two points separately (conditioning circuit, A/D, arithmetic processing) and then find the difference. This method has low accuracy of the temperature difference. The temperature difference measurement inside and outside the library can use the circuit shown in Figure 2, using the temperature difference value to directly compare with the set value, which can ensure higher accuracy, simplify the software design of the system, and improve the reliability of the system. 3.3. Measurement of the Lowest Temperature Value at Point NConnect several AD590s at different temperature measuring points in series, and the lowest temperature value at all measuring points can be measured. This method can be applied to the occasion of measuring the lowest temperature at multiple points. 3.4. Measurement of Average Temperature at Point NConnect N AD590s in parallel, and then average the current after summing, then the average temperature can be obtained. This method is suitable for the occasions where the average temperature of multiple points is required but the specific temperature of each point is not required.IV. ConclusionAD590 integrated temperature sensor is widely used. It is mainly used in engineering to measure thermodynamic temperature, Celsius temperature, temperature difference between two points, minimum temperature at multiple points, average temperature at multiple points, etc. Therefore, it is not only widely used in daily life, but also widely used in industrial automation control systems and automatic detection process control systems. In addition, due to its high accuracy, low price, no auxiliary power supply, and good linearity, AD590 is often used in temperature measurement and temperature detection and control fields.FAQWhat is AD590?AD590 is a temperature sensor, the current output sensitivity is 1μA/℃, the standard output value is 298.2μA at 25℃, and the working voltage range is 4~30V.What are the characteristics of AD590 temperature sensor?Single function (only temperature measurement), small temperature measurement error, low price, fast response speed, long transmission distance, small size, micro power consumption, etc. It is suitable for remote temperature measurement and temperature control without non-linear calibration. The peripheral circuit is simple.How to detect the quality of AD590?AD590 has a current of 273 mA at 0°. Because 2113 is a Wen sensitive resistor 5261, it means that it is greatly affected by the surrounding temperature 4102. It is very difficult to measure without relying on 1653 other tools. Give you some suggestions.When the ambient temperature rises by one degree, the current of AD590 increases by 1uA. What you have to do is to work with AD590 simultaneously with the help of a high-precision temperature test instrument. After AD590 series 10K resistance, measure its voltage, that is to say, it should be 2.73V at 0°, and 2.98V at room temperature 25°.For higher accuracy, it is recommended that you use the electronic building block software Ardunio for measurement, and put the corresponding data into MATLAB for linear regression. The better the linearity, the more stable the measurement.AD590 is not a high-precision temperature testing device. If high-precision testing is required, other components are recommended.What is the difference between AD590 and PT100?AD590 is a current-type temperature sensor. It converts temperature changes into current conversion. The simplest processing is to pass a resistor (10K) after the output to convert the current into a voltage, and then through the detection voltage, the current at this time can be deduced. Use the relationship between current and temperature in the sensor data to calculate the current temperature.PT100 is a resistance type temperature sensor, which converts temperature changes into resistance changes. The simplest process is to place Pt100 in a bridge, use the voltage difference at the midpoint of the bridge arm, and use a differential amplifier circuit (instrument amplifier circuit) Amplify the voltage, use the amplifier gain and bridge structure data, and use the detected voltage to inversely calculate the current resistance value, and use the relationship between resistance and temperature in the PT100 data sheet to calculate the current temperature.Is AD590 a thermocouple or a thermal resistance?It is neither a thermocouple nor a thermal resistance. The main principle is to detect the temperature according to the temperature change, the output current change, and the current size.