The Kynix Components

LM338 is an adjustable 3-terminal positive voltage regulator which capable of supplying in excess of 5A over a 1.2V to 32V output range. This blog will introduce LM338 from its pinout, features to its application circuits, datasheet and including some other information.CatalogLM338 DescriptionLM338 PinoutLM338 FeaturesLM338 ParameterLM338 Functional Block DiagramLM338 Schematic DiagramLM338 CircuitLM338 ApplicationLM338 PackageLM338 ManufacturerComponent DatasheetFAQLM338 DescriptionThe LM338 is an adjustable 3-terminal positive voltage regulator which capable of supplying in excess of 5A over a 1.2-V to 32-V output range. It is exceptionally easy to use and require only 2 resistors to set the output voltage. Careful circuit design has resulted in outstanding load and line regulation, comparable to many commercial power supplies. The LM338 voltage regulator offers full overload protection. The LM338 supplied in a standard 3-lead transistor package. Normally, no capacitors are needed unless the device is situated more than 150 mm (6 inches) from the input filter capacitors in which case an input bypass capacitor is required. An optional output capacitor can be added to improve transient response. The adjustment terminal of the regulator can be bypassed to achieve very high ripple rejection. Refer to the adjustable regulator data sheets below for more information about the LM338 adjustable voltage regulator.LM338 PinoutLM338LM338 PinoutLM338 FeaturesSpecified 7-A Peak Output CurrentSpecified 5-A Output CurrentAdjustable Output Down to 1.2 VSpecified Thermal RegulationCurrent Limit Constant With TemperatureP+ Product Enhancement TestedOutput is Short-Circuit ProtectedLM338 ParameterManufacturer:Texas InstrumentsSeries:-Packaging:TubePart Status:ActiveOutput Configuration:PositiveOutput Type:AdjustableNumber of Regulators:1Voltage - Input (Max):40VVoltage - Output (Min/Fixed):1．24VVoltage - Output (Max):32VVoltage Dropout (Max):-Current - Output:5APSRR:75dB ~ 60dB (120Hz)Control Features:-Protection Features:Over Temperature Short CircuitOperating Temperature:0°C ~ 125°CMounting Type:Through HolePackage / Case:TO-220-3Supplier Device Package:TO-220-3Base Part Number:LM338LM338 Functional Block DiagramLM338 Schematic DiagramYou can use this Voltage Regulator Calculator to vary the value of the program resistor (R1) and output set resistor (R2) and calculate the output voltage for the LM338 of three terminal adjustable voltage regulator.  This Voltage Regulator Calculator will work for all voltage regulators with a reference voltage (VREF) of 1.25. For the LM338 and LM350 regulators, 120 ohms is typically used for the program resistor R1. However, other values such as 150 or 220 ohms can also be used for R1. The LM338 voltage regulator can also be configured to regulate current in a circuit.LM338 Schematic diagramLM338 CircuitThe following schematics show typical circuit applications for the LM338 voltage regulator.Note: The dropout voltage of the IC regulator is about 1.5 to 2.5 Volts, depend on the output current (IOUT). Therefore, the input voltage to the  LM338 regulator will need to be at least 1.5V to 2.5V greater than the desired output voltage. Plan to be about 3V of  the desired output voltage. You don't want to use too high an input voltage as the excess will need to be dissipated as heat through the regulator.  See the datasheets of the voltage regulator above for specific details on the voltage drop-off and heatsink requirements.Figure 1. 1.2 to 25V Adjustable Voltage RegulatorWhen using external capacitors with a voltage regulator it may be necessary to use protection diodes to prevent the capacitors from discharging through low current points into the voltage regulator. Even small capacitors can have a low enough internal series resistance to be able to deliver 20A spikes when shortened. Although the surge is very short in duration, there is enough energy to damage parts of the regulator IC. No protection diodes are required for output voltages of less than 25V or greater than 10 uF capacitance. Figure 2 shows the LM338 with protection diodes included for use with voltage outputs greater than 25V and high values of output capacitance.Figure 2. Adjustable Voltage Regulator with Protection DiodesSolid tantalum capacitors can be used on the voltage output to improve the ripple rejection of the voltage regulator.Figure 3. Adjustable Voltage Regulator with Improved Ripple RejectionLM338 ApplicationAdjustable Power SuppliesConstant Current RegulatorsBattery ChargersLM338 PackageLM338 ManufacturerTexas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog chips and embedded processors, which account for more than 80% of its revenue. TI also produces TI digital light processing technology and education technology products including calculators, microcontrollers and multi-core processors. The company holds 45,000 patents worldwide as of 2016.Component DatasheetLM338 Voltage Regulator DatasheetFAQWhat is lm338?The LM138/LM238/LM338 are adjustable 3-terminal positive voltage regulators capable of supplying in excess of 5A over a 1.2V to 32V output range.What is the current rating of voltage regulator IC LM338 K?The LM317 / LM338 / LM350 family of adjustable 3-terminal positive voltage regulators can take a input of 3 to 40 Volts DC and provide a regulated voltage over a 1.2V to 37V output range. The LM317 voltage regulators can provide up to 1.5 Amperes (A) of output current.What is adjustable voltage regulator?An adjustable voltage regulator produces a DC output voltage, which can be adjusted to any other value of certain voltage range. Hence, adjustable voltage regulator is also called as a variable voltage regulator. The DC output voltage value of an adjustable voltage regulator can be either positive or negative.What is function of voltage regulator?A voltage regulator generates a fixed output voltage of a preset magnitude that remains constant regardless of changes to its input voltage or load conditions. There are two types of voltage regulators: linear and switching.How do you test a voltage regulator?The best way to test a voltage regulator is with a multimeter, and what you do is you put your multimeter clamps directly on the battery terminals. Positive read to positive and black to negative. And you said it to voltage, and with the car off, you should have a little over 12 volts. That's that's a healthy battery. 

MAX3232 is a commonly used rs232 to ttl converter ic. This blog will provide you as much information as possible about the MAX3232, including its pinout, features, its differences between MAX232, where and how to use it, etc. Hope this blog helps! This is a tutorial video showing how to convert ttl to rs232 using MAX3232 in details.CatalogMAX3232 DescriptionMAX3232 PinoutMAX3232 FeaturesMAX3232 ParameterMAX3232 SchematicMAX3232 vs MAX232MAX3232 EquivalentWhere to use MAX3232 icHow to use MAX3232 icMAX3232 ApplicationMAX3232 PackageComponent DatasheetMAX3232 DescriptionMAX3232 is a commonly used rs232 to ttl converter ic. It consists of two line drivers, two line receivers, and a dual charge-pump circuit with terminal to terminal ESD protection of 15 kV. (serial-port connection terminals, including GND).  The device complies with TIA/EIA-232-F standards and provides the electrical interface between an asynchronous communication controller and a serial-port connector. The charge pump and four small external capacitors allow the device to operate from a single 3V to 5.5V supply. The devices have data signaling rates of up to 250 kbit/s and a maximum driver output slew rate of 30V/s. When powered from a 3.0V to 5.5V power supply, the max3232 uses a proprietary low-dropout transmitter output stage with dual charge pumps to achieve true RS232 performance. The device only requires four 0.1uF external small size charge pump capacitors. max3232 maintains the RS-232 output level while ensuring a data rate of 120kbps.MAX3232 PinoutMAX3232MAX3232 Pinout Pin NumberPin NameDescription1C1 +Positive lead of C1 capacitor2V+Positive charge pump output for storage capacitor only3C1 -Negative lead of C1 capacitor4C2+Positive lead of C2 capacitor5C2-Negative lead of C2 capacitor6V-Negative charge pump output for storage capacitor only7DOUT2RS232 line data output (to remote RS232 system) 8RIN2RS232 line data input (from remote RS232 system) 9ROUT2Logic data output (to UART)10DIN2Logic data input (from UART)11DIN1Logic data input (from UART) 12ROUT1Logic data output (to UART)13RIN1RS232 line data input (from remote RS232 system)14DOUT1RS232 line data output (to remote RS232 system)15GroundConnects to the ground of the circuit16VccSupply Voltage, Connect to external 3V to 5.5V power supplyMAX3232 FeaturesRS-232 Bus-Terminal ESD Protection Exceeds±15 kV Using Human-Body Model (HBM)Meets or Exceeds the Requirements of TIA/EIA-232-F and ITU V.28 StandardsOperates With 3-V to 5.5-V VCC SupplyOperates up to 250 kbit/sTwo Drivers and Two ReceiversLow Supply Current: 300 µA TypicalExternal Capacitors: 4 × 0.1 µFAccepts 5-V Logic Input With 3.3-V SupplyAlternative High-Speed Terminal-Compatible Devices (1 Mbit/s): SN65C3232 (–40°C to 85°C)/SN75C3232 (0°C to 70°C)MAX3232 ParameterManufacturer:Texas InstrumentsSeries:-Packaging:Tape & Reel (TR)Part Status:ActiveType:TransceiverProtocol:RS232Number of Drivers/Receivers:2/2Duplex:FullData Rate:250kbpsVoltage - Supply:3V ~ 5．5VOperating Temperature:0°C ~ 70°CMounting Type:Surface MountPackage / Case:16-SOIC (0．154" 3．90mm Width)Supplier Device Package:16-SOICReceiver Hysteresis:300mVBase Part Number:MAX3232MAX3232 SchematicMAX3232 vs MAX232MAX232MAX232 is a  single power supply level conversion chip for the RS-232 standard serial port. It uses +5v single power supply. The device is ideal for battery-powered systems due to its low-power shutdown mode, which can reduce power consumption to less than 5uW. The MAX225, MAX233, MAX235, and MAX245/MAX246/MAX247 do not require any external components and are ideal for applications with limited printed circuit board space. There is no difference in performance between the two. Differences:MAX232 is powered by 5V voltage, and max3232 is powered by 5V or 3.3V voltage.The power consumption of MAX232 is large, when the supply voltage is 5V, the power consumption is 5mA; while the power consumption of MAX3232 is small, when the supply voltage is 5V or 3.3V, the power consumption is 0.3mA.MAX232 externally connected with four 1uF capacitors; while MAX3232 externally connected with four 0.1uF capacitors.MAX232 general civilian product application; and MAX3232 general military use (such as aerospace and other places with strict power consumption requirements).The price is slightly different.MAX3232 EquivalentThe equivalent ic to MAX3232 is MAX232. Both ICs have the same pin-out and package style, so they are a direct substitute. The main improvement in MAX3232 is that it can support both 3.3V and 5V systems, whereas the predecessor MAX232 could only support 5V systems. As a result, if you are working with a 3.3V system, MAX3232 is a better choice than MAX232 because it avoids the problem of logic level conversion.Where to use MAX3232 icMAX3232 is a TTL/CMOS to RS232 converter. Most of our microcontrollers (PIC/ARM/Atmel) operate on TTL/CMOS logic, which means they communicate via 0V or +5V, whereas our computers use RS232, which operates at logic levels -24V or +24V.  So, in order to connect these microcontrollers to a computer, we must convert the TTL/CMOS logic to RS232 logic. As a result, if you're looking for an IC to perform this conversion and interface a Microcontroller with your computer, this is the one.How to use MAX3232 icThis integrated circuit is simple to set up and use. The IC operates on 3.3V/+5V, so power the Vcc with the required voltage and connect the ground pin to the circuit ground. The IC also requires four capacitors, which can range in value from 1uF to 22uF. The IC can assist you in converting two logic levels, which means you can use two Microcontrollers, but to get started, we will use only one MCU and connect it to a computer; the complete circuit is shown below. Because we are not using the second module, the pins (T2 out, R2 in, T2 in, R2 out) are left free.Every microcontroller that supports serial communication will have a Tx and a Rx pin. These two pins should be connected to the T1 in (pin 10) and R1 out (pin 13) pins. This is the TTL/CMOS logic inputs, and the converter RS232 logic signals can be obtained from R1 in (pin 13) and T1 out (pin 14). You may be wondering how a 3.3V/5V signal is converted to a +25V signal when the IC is powered by 3.3V/5V. This is made possible by a charge pump method, which consists of a capacitor that charges up to provide 25V.MAX3232 ApplicationBattery-Powered SystemsPDAsNotebooksLaptopsPalmtop PCsHand-Held EquipmentMAX3232 PackageComponent DatasheetMAX3232 Datasheet 

What is ULN2803?The ULN2803 is a relay driver. The ULN2803 is a relay driver with a Darlington transistor array that can operate at high voltages and currents. The Darlington pairs are connected in a parallel configuration to increase current capability. The component contains eight NPN Darlington pairs with high-voltage outputs and common-cathode clamp diodes that are directly related to switching inductive loads. Each Darlington pair has a collector-current rating of around 500 mA.This blog provides you with a basic overview of the ULN2803 transistor, including its pin descriptions, functions and specifications, alternative products, etc., to help you quickly understand what ULN2803 is. We will be glad to find that this blog can be useful for people loving electronic components.CatalogULN2803 PinoutULN2803 CircuitULN2803 ApplicationsULN2803 FeaturesULN2803 AdvantageULN2803 PackageULN2803 ParametersULN2803 EquivalentsWhere to use ULN2803ULN2803 ManufacturerHow is ULN2803 WorkingComponent DatasheetFAQULN2803 PinoutPin NumberDescriptionBASE CONNECTIONS for DARLINGTON ARRAYs11B-Base of 1st Transistor22B- Base of 2nd Transistor33B- Base of 3rd Transistor44B- Base of 4th Transistor55B- Base of 5th Transistor66B- Base of 6th Transistor77B- Base of 7th Transistor88B- Base of 8th TransistorSHARED TERMINALS9GND- Emitter of all Transistor s10COM- Common cathode (Negative) node for flyback diodes. COLLECTOR CONNECTIONS for DARLINGTON ARRAYs118C-Collector of 8th Transistor127C-Collector of 7th Transistor136C-Collector of 6th Transistor145C-Collector of 5th Transistor154C-Collector of 4th Transistor163C-Collector of 3rd Transistor172C-Collector of 2nd Transistor181C-Collector of 1st TransistorULN2803 CircuitULN2803 Circuit 1ULN2803 Circuit 2ULN2803 ApplicationsULN2803 is widely used in the following applications:Hammer driversDisplay driversLogic BuffersGas & LED dischargerLogic buffersRelay driversLamp driversLine driversULN2803 FeaturesThe specifications, as well as features of ULN2803, are as follow:The allowed maximum voltage between emitter & collector for each and every Darlington transistor is 50 volts.The maximum current that is allowed to flow through the collector of every Darlington pair is 500 mA.Between the emitter and base of the Darlington pair, the maximum voltage that is allowed is 30 volts.In each Darlington pair, a fly-back diode is present and the maximum current that is allowed to pass through that is 500 mA.The rise time is 130 ns.Typically, the fall time is 20micro-second.The operating temperature of ULN2803 lies in the range of -65°C – 150°C.In order to operate this chip, no additional power is needed.ULN2803 AdvantageULN2803 ChipULN2803 is a high-voltage, high-current transistor array IC, especially for microcontrollers that need to drive high-power loads. The IC consists of eight NPN Darlington-connected transistors and a common clamp diode to switch the load connected to the output. This IC is widely used to drive high loads, such as lamps, relays, motors, etc. Its rated current is usually 50v / 500mA.ULN2803 PackageHere we take ULN2803A as an example to introduce ULN2803 package.ULN2803 ParametersDrivers per package8Switching voltage (Max) (V)50Output voltage (Max) (V)50Peak output current (mA)500Delay time (Typ) (ns)130Input compatibilityCMOS, TTLVol @ lowest spec current (Typ) (mV)900Iout/ch (Max) (mA)500Iout_off (Typ) (uA)50RatingCatalog ULN2803 EquivalentsThere are no PIN-to-PIN replacements for ULN2803 but there are similar functioning ICs like ULN2003, ULN2004. You can remodel eight Darligngton Transistors or eight MOSFETs to substitute for ULN2803.Where to use ULN2803The ULN2803 chip can be used in the following cases:To control the inductive loads those are making use of the logic obtained by the control unit. In ULN2803, the Darlington array act as separate 8 individual switches and thus can be turned off and on as desired. Each set of these Darlington pair is capable of driving high power loads that use logic from the control unit.If you are willing to drive multiple loads, then this chip can be used as it is capable of driving eight loads at a time. However, the MOSFETs, as well as transistors that are being used in this chip, will suffice and also placing eight loads at the same time will be a cumbersome job but this chip is widely used in order to replace the bulk switching devices.This chip can also be used for programmable load sharing. if we are having one low power load as well as one high power load then multiple arrays can be connected in parallel in order to drive the high power load.ULN2803 ManufacturerTexas Instruments Inc. (TI)  is an American technology company that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. Its headquarters are in Dallas, Texas, United States. TI is one of the top ten semiconductor companies worldwide, based on sales volume. Texas Instruments's focus is on developing analog chips and embedded processors, which accounts for more than 80% of their revenue. TI also produces TI digital light processing (DLP) technology and education technology products including calculators, microcontrollers and multi-core processors. To date, TI has more than 43,000 patents worldwide.How is ULN2803 WorkingThe ULN2803 IC consists of eight NPN Darlington pair which provides the proper current amplification required by the loads. We all know that the transistors are used to amplify the current but here Darlington transistor pairs are used inside the IC to make the required amplification.A Darlignton pair is two transistors that act as a single transistor providing high current gain. In this pair the current amplified by the first transistor is further amplified by the next transistor providing high current to the output terminal.When no base voltage is applied that when is no signal is given to the input pins of the IC , there will be no base current and transistor remains in off state. When high logic is fed to the input both the transistors begin to conduct providing a path to ground for the external load that the output is connected. Thus when an input is applied corresponding output pin drops down to zero there by enabling the load connected to complete its path.Component DatasheetULN2803A DatasheetFAQWhat is ULN2803?ULN2803 is a high-voltage and high-current Darlington transistor array and is mainly used as a relay driver with an ability to handle 8 relays at a time.It comes with a collector-emitter voltage around 50 V and input voltage residing at 30 V.What is the use of ULN2803 in driving a relay?Explanation: We need a ULN2803 for driving a relay because the relay coil requires 10mA or more current to be energized. If microcontroller pins are not able to provide sufficient current to drive relays then we need ULN2803 for driving relays.How do you use ULN2803?ULN2803 is a High voltage, high current Transistor Array IC used especially with Microcontrollers where we need to drive high power loads. Thic IC consists of a eight NPN Darlington connected transistors with common Clamp diodes for switching the loads connected to the output. 

I Introduction In this blog, we compare the LM339 and LM339N produced by TI. The content of comparison includes component parameters, packaging, application areas, and their circuit diagrams, etc. Hope this blog is helpful to those interested in LM339 or LM339N.LM339NCatalogI IntroductionII Component DatasheetIII Difference Between LM339 and LM339NIV ParametersV FeaturesVI ApplicationsVII PinoutFAQOrdering & QuantityII Component DatasheetComponent Datasheet 1LM339N DatasheetComponent Datasheet 2LM339 DatasheetIII Difference Between LM339 and LM339N◾LM339N is a quad voltage comparator. It adopts dual in-line 14-pin package. The maximum operating voltage is ±18V and the power consumption is 265mW. It is used in induction cookers and other products.◾LM339 (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. LM339 common mode range is very large, from 0v to the power supply voltage－1.5v; wide supply voltage range: single power supply is 2-36V; dual power supply voltage is ±1V~±18V.IV ParametersParametersLM339NLM339Number of channels (#)44Output typeOpen-collector, Open-drainOpen-collectorPropagation delay time (µs)0.70.3Vs (Max) (V)3630Vs (Min) (V)22Vos (offset voltage @ 25 C) (Max) (mV)55Iq per channel (Typ) (mA)0.20.2Input bias current (+/-) (Max) (nA)25050Rail-to-railOutOutRatingCatalogCatalogOperating temperature range (C)0 to 700 to 70FeaturesStandard comparatorStandard comparatorVICR (Max) (V)3428.5VICR (Min) (V)00Approx. price (US$)1ku | 0.241ku | 0.05V FeaturesLM339NLM339Wide Supply Voltage RangeLM139/139A Series 2 to 36 VDC or ±1to ±18 VDCLM2901-N: 2 to 36 VDC or ±1 to ±18 VDCLM3302-N: 2 to 28 VDC or ±1 to ±14 VDCVery Low Supply Current Drain (0.8 mA) –Independent of Supply VoltageLow Input Biasing Current: 25 nALow Input Offset Current: ±5 nAOffset Voltage: ±3 mVInput Common-Mode Voltage Range IncludesGNDDifferential Input Voltage Range Equal tothe Power Supply VoltageLow Output Saturation Voltage: 250 mV at 4 mAOutput Voltage Compatible With TTL, DTL, ECL,MOS, and CMOS Logic SystemsWide Supply RangesSingle Supply: 2 V to 36 V(Tested to 30 V for Non-V Devices and32 V for V-Suffix Devices)Dual Supplies: ±1 V to ±18 V(Tested to ±15 V for Non-V Devices and±16 V for V-Suffix Devices)Low Supply-Current Drain Independent ofSupply Voltage: 0.8 mA (Typical)Low Input Bias Current: 25 nA (Typical)Low Input Offset Current: 3 nA (Typical) (LM139)Low Input Offset Voltage: 2 mV (Typical)Common-Mode Input Voltage RangeIncludes GroundDifferential Input Voltage Range Equal to Maximum-Rated Supply Voltage: ±36 VLow Output Saturation VoltageOutput Compatible With TTL, MOS, and CMOSOn Products Compliant to MIL-PRF-38535,All Parameters Are Tested Unless Otherwise Noted. On All Other Products, Production Processing Does Not Necessarily Include Testing of All Parameters.VI ApplicationsLM339NLM339High-Precision Comparators Reduced VOS Drift Overtemperature Eliminates Need for Dual Supplies Allows Sensing Near GND Compatible With All Forms of Logic Power Drain Suitable for Battery OperationIndustrialAutomotiveInfotainment and ClustersBody Control ModulesPower SupervisionOscillatorsPeak DetectorsLogic Voltage TranslationVII PinoutLM339 and LM339N share the same pinout diagramFAQWhat 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.

The PCF8574T IO Expansion Board is used as remote 8-bit I/O expander for I2C-bus. CatalogProduct OverviewCAD ModelProduct PinoutPCF8574T AttributesFamily OverviewApplicationsPCF8574T-DatasheetPCF8574T CircuitPCF8574T Raspberry PiReferencePCF8574T FAQProduct OverviewThe PCF8574T IO Expansion Board is used as remote 8-bit I/O expander for I2C-bus.Up to 8 PCF8574T IO Expansion Board can be connected to the I2C-bus, providing up to 64 I/O ports. The PCF8574T IO Expansion Board features allowing the use of multi module connected to the I2C bus at the same time by connecting the pinheader and connector.There is a small potentiometer onboard, which can adjust the backlight of LCD1602 or LCD2004, and a jumper cap to control the switch of the LED light. CAD Model PCF8574T-Part Symbol  PCF8574T-Footprint  PCF8574T-3D-Model Product Pinout PCF8574T-Pinout PCF8574T AttributesSource Content uid:PCF8574TManufacturer Part Number:PCF8574TPart Life Cycle Code:ActiveIhs Manufacturer:NXP SEMICONDUCTORSPart Package Code:SOICPackage Description:SOP, SOP16,.4Pin Count:16Reach Compliance Code:compliantECCN Code:EAR99HTS Code:8542.39.00.01Manufacturer:NXP SemiconductorsRisk Rank:1.53Samacsys Description:NXP - PCF8574T. - IC, SM I/O EXPANDER 8-BITSamacsys Manufacturer:NXPClock Frequency-Max:0.1 MHzExternal Data Bus Width:1JESD-30 Code:R-PDSO-G16Length:10.3 mmMoisture Sensitivity Level:2Number of Bits:8Number of I/O Lines:8Number of Ports:1Number of Terminals:16Operating Temperature-Max:85 °COperating Temperature-Min:-40 °CPackage Body Material:PLASTIC/EPOXYPackage Code:SOPPackage Equivalence Code:SOP16,.4Package Shape:RECTANGULARPackage Style:SMALL OUTLINEPeak Reflow Temperature (Cel):260Power Supplies:3/5 V Family OverviewFamily overview The Philips family of I2C/SMBus General Purpose parallel Input/Output (GPIO) devices provides a simple solution for application requiring more I/Os. About 20 different devices can be chosen from two sub-families, commonly called ‘quasi bi-directional General Purpose I/Os’ and ‘totem-pole General Purpose I/Os’. Devices can be chosen with 4-bit, 8-bit or 16-bit width. Additional features (not available on all the devices) are active-LOW Interrupt output, active-LOW Reset input, programmable I2C address pins and low power consumption. Finally, some devices come with additional functions (EEPROM, DIP switch) providing integrated and price attractive combination solutions. Quasi bi-directional GPIOs use a push-pull I/O port with an internal weak current-source pull-up to keep the port HIGH since the upper transistor is on for only 1⁄ 2 clock cycle. Totem-pole GPIOs use a configuration register that programs an I/O port as either an input or output. Devices with a Reset input pin (RESET) can be set to a known default state by a master device when, for instance, an ‘I2C-bus hung’ situation occurs, thus allowing the master to take control of the bus without having to cycle power to the device. Devices with an Interrupt output pin (INT) are able to provide an ‘input change’ status to a master device anytime an I/O used as an input changes its logic state. Programmable I2C address pins allow more than one device in the same I2C-bus without any address conflicts. Low power consumption GPIOs are attractive for portable applications or in general any application where current consumption is a key parameter. The following is a selection guide that provides the designers and engineers with an overview of the similarities and important differences, allowing them to select the best port expander for the job. Even though important technical details are explained in this application note, the reader is encouraged to thoroughly review the data sheets for specific information on the device. ApplicationsKeypad and switch controlACPI power switch, relays, timerLED controlSignal monitoringSensors, fan control PCF8574T-DatasheetYou can download the datasheet from the link given below:PCF8574T-Datasheet PCF8574T CircuitInterfacing Arduino with I2C LCD circuit:Example circuit diagram is shown in the image below.The main component of the I2C LCD display is the PCF8574 I/O expander, with only two pins SDA and SCL we get a maximum of 8 pins from P0 to P7. PCF8574A also can be used but it has a different address.All LCD data pins are connected to the PCF8574 where: RS, RW, E, D4, D5, D6 and D7 are connected to P0, P1, P2, P4, P5, P6 and P7 respectively.PCF8574 I/O expander SDA and SCL pins are connected to Arduino pin A4 and A5 respectively (Arduino SDA and SCL pins).PCF8574 I/O expander A0, A1 and A2 pins are the address pins which decide the I2C address of the chip. In this example each pin is connected to +5V through a 10k ohm resistor (the 10k resistor is optional, each pin can be connected directly to +5V).The I2C address of the PCF8574 is: 0x20 | A2 A1 A0 ( | means OR)In our circuit A2, A1 and A0 are connected to +5V (through 10k resistors) which means the I2C address is equal to 0x20 | 7 = 0x27If the PCF8574A is used instead of the PCF8574 the I2C address is: 0x38 | 7 = 0x3F. PCF8574T Raspberry PiComimark 3Pcs PCF8574 PCF8574T I2C 8 Bit IO GPIO Expander Module for Arduino & Raspberry PiI2C interface, I / O expansion module, two I / O scalability 8 I / O (up to 8 simultaneous use the PCF8574 expanded to 64 I / O)Typical application: I / O resource shortage MCU I / O expansionMain resources: the PCF8574 I2C interface, 8-bit parallelPackage Included: 3 x PCF8574 IO Expansion Board I/O Expander I2C-Bus Evaluation Development Module ReferencePCF8574T Chip Datasheet: File:PCF8574T Datasheet.pdfWiringPi: [ http://wiringpi.com/extensions/i2c-pcf8574/ ]telecnatron:[ https://telecnatron.com/articles/Utility-To-Control-1602-LCD-On-Raspberry-Pi-Via-A-PCF8574-I2C-Backpack-Module/index.html]Circuitbasics:[ https://www.circuitbasics.com/raspberry-pi-i2c-lcd-set-up-and-programming/ ] PCF8574T FAQWhat is pcf8574t?The PCF8574/74A provides general-purpose remote I/O expansion via the two-wire bidirectional I2C-bus (serial clock (SCL), serial data (SDA)). The devices consist of eight quasi-bidirectional ports, 100 kHz I2C-bus interface, three hardware address inputs and interrupt output operating between 2.5 V and 6 V. How connect PCF8574 to Arduino?1.Use PCF8574(A) I2C GPIO to add more digital pins to Arduino.2.Components.3.Set the PCF8574/PCF8574A I2C Address.4.Connect the PCF8574/PCF8574A GPIO Module to the Arduino.5.Connect the Button and the LED Modules.6.Connect the Power Wires together.7.Step 6: Connect the Ground Wires together. How do I program PCF8574?After connecting the I2C Module to LCD, connect the GND and VCC pins of the PCF8574 Module to GND and 5V pins of Arduino. Finally, the SDA and SCL Pins. Connect them to pins A4 and A5 pins of Arduino UNO respectively. What is I2C IO Expander?The I2C-bus allows easy two-line communication between two devices using a serial data line (SDA) and a serial clock line (SCL) and, as a result, is a popular choice for computing, consumer electronics, communication, and industrial systems. What is the function of an IO Expander?NXP's general-purpose input/output (GPIO) expanders are a simple, cost-effective way to monitor and control several peripheral signals. They make it easy for designers to add extra I/O to their design and thereby free up the microprocessor's GPIO for other, more important functions. 

I DescriptionThis blog will introduce 8 simple and easy to understand circuits that using TL431 as the main component. Such as TL431 Precision Reference Voltage Circuits, TL431 Adjustable Regulated Power Supply Circuit, etc. Hope this blog can help beginners to better understand TL431 Shunt Regualtor.Electronics Tutorial - The TL431 Part 1/3 - Getting to know the componentI DescriptionII TL431 Precision Reference Voltage SourceIII TL431 Adjustable Regulated Power SupplyIV TL431 Overvoltage Protection CircuitV TL431 Constant Current Source CircuitVI TL431 ComparatorVII TL431 Voltage MonitorVIII TL431 Controllable Shunt CharacteristicsIX TL431 Switching Power SupplyComponent DatasheetFAQOrdering & QuantityII TL431 Precision Reference Voltage SourceThe precision reference voltage source circuit has good temperature stability and large output current. But when connecting capacitive loads, we should pay attention to the value of CL to avoid self-excitation.Figure 1. TL431 Circuit: Precision Reference Voltage SourceIII TL431 Adjustable Regulated Power SupplyAs shown in the figure, Vo can be adjusted between 2.5~36V.V0=Vref(1+R1/R2)(Vref=2.5v).Since the withstand voltage is related to (Vi -Vo), when the voltage difference is large, the power consumption of R increases.Figure 2. TL431 Circuit: Adjustable Regulated Power SupplyIV TL431 Overvoltage Protection CircuitAs shown in the figure, when Vi exceeds a certain voltage, TL431 triggers. At this time, the thyristor is turned on and generates a large instantaneous current, which blows the fuse, thereby protecting the rear circuit. V protection point = (1+R1/R2)Vref.Figure 3. TL431 Circuit: Overvoltage ProtectionV TL431 Constant Current Source CircuitAs the picture shows. The constant current value is related to Vref and the external resistance, and the margin should be considered when selecting the power transistor. This constant current source can be used as a current limiter if it is connected to a stabilized circuit.Figure 4. TL431 Circuit: Constant Current SourceVI TL431 ComparatorAs shown in the figure, it cleverly uses the critical voltage of Vref=2.5v. Due to the small internal resistance of the TL431, the input and output waveforms track well. Figure 5. TL431 Circuit: ComparatorVII TL431 Voltage MonitorAs shown in the figure, use the transfer characteristics of TL431 to form a practical voltage monitor. When the voltage is between the upper and lower limit voltages, the LED power and upper and lower limit voltages are (1+R1/R2)Vref and (1+R3/R4)Vref respectively. Figure 6.TL431 Circuit: Voltage MonitorVIII TL431 Controllable Shunt CharacteristicsIt can be seen from the functional module diagram of TL431 that when the voltage at the REF terminal changes slightly, the shunt from the cathode to the anode will change within 1-100mA. With this controllable shunt feature, small voltage changes can be used to control relays, indicator lights, etc., and even directly drive audio current loads. The picture shows a simple 400mW mono power amplifier circuit for this application. Figure 7. TL431 Circuit: Controllable Shunt CharacteristicsIX TL431 Switching Power SupplyIn the past ordinary switching power supply design, the output voltage is usually fed back directly to the input terminal after error amplification. This voltage control mode can also work well in some applications. However, with the development of technology, most of the world's power supply manufacturing industry has adopted a scheme with a similar topology.The switching power supply of this kind of structure has the following characteristics:The output is fed back by TL431 (controllable shunt reference) and the error is amplified. The sinking end of TL431 drives the light-emitting part of an optocoupler. The feedback voltage obtained by the photosensitive part of the photocoupler on the main side of the power supply is used to adjust the switching time of a current mode PWM controller. Thus, a stable DC voltage output is obtained.Figure 8. TL431 Circuit: Switching Power SupplyThe picture above is a practical 4W switch type 5V DC regulated power supply circuit. This circuit adopts this kind of topological structure and uses TOPSwitch technology at the same time.In the picture:C1, L1, C8 and C9 constitute an EMI filter;BR1 and C2 rectify and filter the input AC voltage;D1 and D2 are used to eliminate the spike voltage caused by transformer leakage inductance;U1 is a current mode PWM controller chip with built-in MOSFET, which accepts feedback and controls the operation of the entire circuit;D3 and C3 are the sub-pole rectifier filter circuit;L2 and C4 form a low-pass filter to reduce the output ripple voltage;R2 and R3 are output sampling resistors, and the divided voltage of the output is controlled by the REF terminal of TL431 to control the shunt of the device from the cathode to the anode.This current directly drives the light-emitting part of the optocoupler U2.Then when the output voltage has a tendency to increase, the Vref will increase and the current flowing through the TL431 will increase. Therefore, the light-emitting of the optocoupler is strengthened, and the feedback voltage obtained by the photosensitive terminal is also greater. U1 will change the switching time of the MOSFET after receiving this increased feedback voltage, and the output voltage will drop with the change. In fact, the process described above will reach equilibrium in a very short time. When balanced, Vref=2.5V, and R2=R3, so the output is stable 5V.It should be noted here that the output voltage can no longer be changed by simply changing the values ​​of the sampling resistors R2 and R3. Because, the parameter of each component in the switching power supply will have a great influence on the working state of the whole circuit. According to the parameters shown in the figure:The circuit can be within the input range of 90VAC～264VAC (50/60Hz);Output +5V;The accuracy is better than ±3%;The output power is 4W;The maximum output current can reach 0.8A;The typical conversion efficiency is 70%.Component DatasheetTL431 DatasheetFAQWhat is the Use of TL431?The TL431 is a "Programmable Precision Reference" and is commonly used in switching power supplies, where it provides feedback indicating if the output voltage is too high or too low. By using a special circuit called a bandgap, the TL431 provides a stable voltage reference across a wide temperature range.What is TL431 Transistor?The TL431 is a Regulator Diode whose output voltage can be programmed by changing the value of resistors connected to it. It acts almost like a Zener diode except for that the voltage rating of this IC is programmable. It is commonly used to provide negative or positive voltage references.How does a Shunt Regulator Work?The Shunt Regulator or Shunt Voltage Regulator is a form of voltage regulator where the regulating element shunts the current to ground. The shunt regulator operates by maintaining a constant voltage across its terminals and it takes up the surplus current to maintain the voltage across the load.