Overview: This article explores LED drivers, their types, design considerations, and applications, highlighting how they ensure efficient, reliable, and long-lasting LED lighting systems.Light-emitting diodes (LEDs) are semiconductor devices that have become the primary technology for modern lighting applications, from smartphone displays to large-scale digital billboards. Beyond visible light applications, LEDs serve various specialized functions. Recent advances have significantly improved their cost-effectiveness and performance, leading to wide adoption across multiple industries.Unlike conventional incandescent or fluorescent lights, LEDs require precise current regulation to function properly. Direct connection to a power source without proper current control can result in device failure or reduced lifespan. LED drivers address this fundamental requirement by providing the necessary current regulation and voltage conversion.What is an LED driver?An LED driver is a power regulation circuit designed to control the electrical characteristics supplied to an LED or LED array. The primary function of an LED driver is to maintain constant current output in varying input voltage and environmental conditions.LED driver performance directly impacts LED system efficiency and reliability. To maximize the advantages of LED technology, drivers must meet several design requirements: high power conversion efficiency, compact form factor, proper construction for extended operation, compliance with electromagnetic compatibility standards, and precise current control across varying load conditions.Types of LED DriversBased on the integration of the driver with the LED systemThere are two types, as shown in Fig. 1Integrated driverExternal driver Fig. 1 Integration of the driver with the LEDs: a) Integrated driver, b) External driver. Source: IEEE AccessIntegrated driverIn an integrated structure, the driver is built into the fixture, offering a simple, compact installation but potential heat management issues as the driver and LEDs share a single housing. There are two types: internal drivers, which are permanently installed and require replacement of the whole fixture if they fail, and plug-and-play drivers, which are replaceable via standard connections. They are ideal for residential and small commercial spaces.External driverExternal structures keep the driver separate from the LEDs, enabling better heat dissipation and a longer lifespan, but installation is more complex due to wiring, electromagnetic interference, and grounding requirements. These are preferred for outdoor, street, and industrial lighting where reliability and longevity are most important.Based on primary operating modes:LED drivers are classified into two typesConstant Current (CC) LED driversConstant Voltage (CV) LED driversThese fundamental approaches determine how the driver maintains stable output characteristics under varying load and input conditions.Constant current driversLEDs are highly sensitive to current changes; excessive current can cause overheating and failure, while insufficient current results in poor brightness. CC LED drivers provide a stable current to LEDs, regardless of fluctuations in their forward voltage or changes in the number of LEDs connected in series, up to the driver’s maximum voltage limit. By maintaining a steady current, CC drivers maximize LED lifespan and ensure consistent performance.CC drivers are preferred for high-power LEDs, such as those used in street lighting, high-bay fixtures, and commercial signage, where consistent brightness and reliability are essential. Typical output currents for commercial CC drivers are 350 mA, 700 mA, 1050 mA, and others. CC drivers are compatible with both constant current reduction (also called analog dimming) and pulse width modulation (PWM) dimming methods.Constant voltage driversConstant voltage drivers maintain a stable voltage output across the LED load while allowing current to vary within specified operating limits. Since LEDs require precise current for optimal operation, CV driver systems typically incorporate impedance elements (such as current-limiting resistors) between the driver output and LED connections.Commercial CV drivers commonly provide standardized output voltages of 12 V and 24 V, corresponding to typical LED strip and module voltage requirements. Unlike CC drivers, CV drivers require only PWM control to maintain proper LED current regulation during dimming operations.Based on different circuit topologiesBoth regulation CC and CV modes can be implemented using various circuit topologies, includingBuckBoostBuck-BoostSEPIC(Single-Ended Primary Inductor Converter)FlybackCukCharge PumpBased on their input power sourceLED systems fall into two main categories, as shown in Fig. 2AC-supplied systemDC-supplied systems Fig. 2 Classification of LED systems based on power source. a) AC-LED system b) DC-LED system Source: IEEE AccessAC-supplied LED systems use different circuit blocks than their DC counterparts and can power both DC-LED modules and AC-LED modules. DC-LED systems are applied in direct current-powered environments, including automotive systems and Power-over-Ethernet applications.ApplicationsAn LED driver has several key applications, each with distinct requirements, which are listed below. General lighting includes indoor systems like bulbs, lamps, and tubes, which are AC-powered, cost-sensitive, and must efficiently manage heat within compact designs. Street lighting is subject to temperature swings and surges, demanding an improved thermal and magnetic design, strong surge protection, and sometimes powers IoT or telecom features for smart city integration.Automotive lighting, including both exterior (headlights, tail lights) and interior (cabin, dashboard), requires high reliability and efficiency, to handle large voltage fluctuations, transients, and low quiescent current to avoid draining batteries.Specialized LED lighting includes grow lights, which offer tunable spectra for plants and require low ripple and humidity-safe, multi-string drivers. UV LEDs are used for curing and disinfection, with flexible power needs. Portable lights prioritize efficiency, robustness, and low weight. Decorative lights focus on low cost and multi-color support. Signage/traffic lights demand high reliability, efficiency, and operation under harsh conditions.Display LED applications cover large billboards and micro-LED panels, which use multiplexing and parallelization for high-quality visuals. LCD backlighting relies on efficient, high-contrast dimming for optimal battery life and image quality. LED animation enables dynamic color mixing and pattern control, while status indication requires precise current for uniform brightness and longevity.Future trends in LED drivers focus on higher efficiency, greater integration, and smart connectivity for IoT and emerging uses like visible light communication.An effective LED driver to considerTexas Instruments TPS92512 It is a highly efficient, integrated buck (step-down) LED driver designed to power high-brightness LEDs in a variety of lighting applications. It operates over a wide input voltage range of 4.5 V to 60 V, making it suitable for both low- and high-voltage systems. The device can deliver up to 2.5 A of output current and features an integrated MOSFET, which simplifies the design and minimizes external components. Fig. 3 TPS92512 Buck LED Driver. Source: Texas InstrumentsThe TPS92512, as shown in Fig. 3, supports analog and PWM dimming, providing flexible brightness control for different lighting needs. Its robust design and precise current regulation makes it ideal for commercial, industrial, emergency, and street lighting applications, where reliability and efficiency are essential.Summarizing the Key PointsLED drivers are essential for regulating current and voltage, ensuring LED longevity, stability, and optimal performance across various lighting applications and environmental conditions.Designing LED drivers involves considerations for efficiency, thermal management, EMI standards, and matching electrical characteristics to prevent system limitations and ensure reliability.Future LED driver developments focus on higher efficiency, greater integration, IoT connectivity, and support for advanced lighting solutions like visible light communication.ReferenceEsteki, M., Khajehoddin, S. A., Safaee, A., & Li, Y. (2023). LED Systems Applications and LED Driver Topologies: A review. IEEE Access, 11, 38324–38358. https://doi.org/10.1109/access.2023.3267673Lamar, D. G. (2020). Latest developments in LED drivers. Electronics, 9(4), 619. https://doi.org/10.3390/electronics9040619LED drivers | TI.com. (n.d.). https://www.ti.com/power-management/led-drivers/overview.htmlFoolish Engineer. (2024, September 15). How to drive LED? What Is LED Driver? Understanding LED Driver | LED Drivers [Video]. YouTube. https://www.youtube.com/watch?v=XDhOvJ_TexETexasInstruments TPS92512- https://www.kynix.com/productdetails/3119083/texasinstruments/tps92512dgqr.htmlTPS92512HV | Buy TI Parts | TI.com. (n.d.). https://www.ti.com/product/TPS92512HV/part-details/TPS92512HVDGQT

Overview: This article explains the working principles and types of solenoid valves, including on-off and proportional, their working mechanisms, and applications in industrial automation and fluid control systems.An electronic actuator is any device that converts electrical energy into mechanical motion or force. These come in many forms, including motors, solenoids, and pneumatic/hydraulic systems controlled electronically. The integration of solenoids into various industries like automotive systems, hydraulic and pneumatic controls, process automation, and home electronics demonstrates their importance in modern technological applications.What is a solenoid?A solenoid is an electromechanical device that converts electrical energy into linear or rotary mechanical motion. The solenoid mechanism has gained widespread adoption due to its operational simplicity, high reliability, and rapid response characteristics.Working Principle of SolenoidIts basic construction consists of a coil wound around a movable ferromagnetic core (plunger), as shown in Fig. 1. When current flows through the coil, a magnetic field is generated, which pulls or pushes the plunger to create mechanical force. The magnetic force increases as the gap between the plunger and core decreases, resulting in a rapid, full-stroke action.Fig. 1 Diagrammatic illustration of the solenoid valve. Source: Rakesh Kumar, Ph.D.Types of SolenoidSolenoid valves are manufactured in numerous configurations and dimensions. Multiple variants exist, differentiated by their flow capacity ratings, operating pressure ranges, and specific internal mechanical designs. They come in two primary categories:On–off typeProportional typeOn-Off SolenoidsOn-off solenoids operate on a binary principle, functioning similarly to basic switches by existing in only two states. Either fully activated (on) or completely deactivated (off). Ideal for simple, binary tasks such as opening/closing valves, activating locks, or switching circuits.Working of Normally On SolenoidsIn a normally open solenoid, the spring holds the plunger in an upward position, maintaining the valve in an open state. When electrical current is applied to the coil, the resulting electromagnetic field pulls the plunger downward, closing the valve. Once the current is interrupted, the electromagnetic force disappears, and the spring pushes the plunger back to its original elevated position, reopening the valve.Working of Normally Off SolenoidsIn a normally closed valve configuration, the spring maintains downward pressure on the plunger, keeping the valve shut. When electricity flows through the coil, it creates an electromagnetic field that overcomes the spring tension, pulling the plunger upward and opening the valve. Upon current stoppage, the electromagnetic field dissipates, allowing the spring to push the plunger back down, returning the valve to its closed position.Though well-suited for simple tasks, these on-off solenoids lack the capability needed for applications that demand exact positioning or adjustable control levels.Proportional SolenoidsProportional solenoids deliver precise, variable control through current modulation. Unlike binary devices, they produce a wide range of outputs, essential for applications demanding accuracy and adaptability. Converting on-off solenoids to proportional operation requires substantial modifications, particularly to their geometric configuration and magnetic pathway design.ApplicationsSolenoid valves are common in controlling the flow of liquids and gases in industrial, medical, and utility applications. They are used to open or close valves in response to electrical signals, automating fluid supply in systems such as HVAC, food processing, pharmaceuticals, and water treatment.They are important in automation and machine control, working with sensors and controllers to synchronize processes in robotics, production lines, and smart infrastructure.Solenoid switches regulate the passage of electricity between power sources and devices, acting as efficient circuit activators and protectors. They enable or interrupt current flow, preventing overloads and optimizing energy use.The automotive sector utilizes solenoids for engine management, fuel injection, braking systems, and transmission control. They also appear in household appliances, aerospace equipment, home automation, etc.Proportional solenoid valves provide precise, variable control of flow rates, making them essential in pneumatic systems, process automation, and applications requiring accurate pressure, level, or temperature regulation.An efficient solenoid valve to considerSMC Series SZ3000 Solenoid ValveThe SMC Series SZ3000 5 Port Solenoid Valve, as shown in Fig. 2, is one of the most efficient solenoid valves. The valve operates on just 0.6 W power consumption (25 mA at 24 VDC), making it significantly more energy-efficient than standard solenoid valves. With a 10-ms response time at 0.5 MPa, the valve provides rapid actuation that enhances system precision and cycle times without sacrificing energy efficiency.Rated for over 50 million operational cycles, this valve delivers extraordinary longevity, reducing maintenance requirements and replacement costs over the system's lifespan. The cassette-type manifold design allows for easy valve replacement without disrupting the entire pneumatic system, minimizing downtime during maintenance.Fig. 2 SZ3000, 5 Port Solenoid Valve Source: SMCWith a manifold height of just 43.5 mm (including DIN rail), the SZ3000 offers space-saving installation while providing full functionality. Available in 2-position, 3-position, and 4-position configurations with various actuation types, the valve adapts to diverse application requirements while maintaining efficiency.These features combine to make the SMC Series SZ3000 (part number SZ3160-5LOZ-C6 for single solenoid or SZ3260-5LOZ-C6 for double solenoid configuration) one of the most efficient and versatile solenoid valve options available for industrial pneumatic applications.Summarizing the Key PointsSolenoids convert electrical energy into mechanical motion, featuring simple design, high reliability, and fast response, making them important in automation and control systems.On-off solenoids operate in binary states, either opening or closing valves, suitable for simple tasks like switches, locks, and circuit manipulation in various industries.Proportional solenoids provide precise, variable control by adjusting current, essential for applications requiring accurate positioning, such as flow regulation and pressure control.Energy-efficient solenoid valves like SMC Series SZ3000 consume minimal power, respond rapidly, and have high durability, reducing maintenance and enhancing system performance.Applications of solenoids include automotive, aerospace, home automation, and industrial systems, where they automate fluid flow, switching, and positioning tasks for enhanced efficiency.ReferenceDüzgün, E., & Şefkat, G. (2024). The Design and Analysis of a Proportional Solenoid with Experimental Validation of Static and Dynamic Behavior. Applied Sciences, 14(24), 11990. https://doi.org/10.3390/app142411990Song, C., & Lee, S. (2015). Design of a Solenoid Actuator with a Magnetic Plunger for Miniaturized Segment Robots. Applied Sciences, 5(3), 595–607. https://doi.org/10.3390/app5030595Wang, S., Weng, Z., & Jin, B. (2020). A performance improvement strategy for Solenoid Electromagnetic actuator in servo proportional valve. Applied Sciences, 10(12), 4352. https://doi.org/10.3390/app10124352The Engineering Mindset. (2019, March 25). Solenoid Basics Explained - working principle [Video]. YouTube. https://www.youtube.com/watch?v=BbmocfETTFoMEP Academy. (2023, February 8). How solenoid valves work [Video]. YouTube. https://www.youtube.com/watch?v=hVVIkQQbSHsSZ3160-5LOZ-C6-https://www.kynix.com/productdetails/33406400/smccorporation/sz31605lozc6.htmlSZ3260-5LOZ-C6-https://www.kynix.com/productdetails/60300474/smccorporation/sz32605lozc6.html

Overview: This article explores the SPI communication protocol, detailing its components, working principles, and applications in IoT and embedded systems for efficient data exchange.The SPI communication protocol is the recommended option for applications needing quick and effective data interchange in IoT sensors, memory modules, and display controllers because it offers excellent data transfer rates.What is an SPI?The serial peripheral interface (SPI) is a 4-wire, serial, synchronous, full-duplex communication protocol for data exchange between a microcontroller and peripheral devices. It was introduced by Motorola and is based on a master-slave architecture featuring one master (controller) and one or more slaves (peripherals).Key ComponentsSPI uses separate clock signals, and the term "4-wire" refers to communication between a master device and one or more slave devices using four signal lines, enabling simultaneous data transmission and reception, as shown in Fig. 1.Fig. 1. Diagrammatic illustration of SPI framework. Source: Journal of Physics Conference SeriesChip Select (CS)The master uses this line to select the specific slave device it wants to communicate with. For systems with multiple slaves, each device can have a dedicated CS line or multiple devices can be managed with fewer CS lines.Serial Clock (SCLK)The master generates this clock signal to synchronize data transfer between devices. Only the master generates the SCLK signal, and the slave cannot initiate communication or adjust the clock.Master Out Slave In (MOSI)This line carries data from the master to the slave. The data is transmitted serially, starting with the most significant bit (MSB).Master In Slave Out (MISO)This line carries data from the slave back to the master. The data is sent serially, often starting with the least significant bit (LSB).Working PrincipleThe data transmission is initiated by pulling the CS line low, and the master directly selects the target device. This CS line eliminates the need for explicit addressing required in protocols like I2C and CAN bus. After the master pulls the CS line low, it generates the clock signal to ensure both master and slave devices are synchronized.MOSI begins to send data from the master to the slave. The data is sent serially, bit by bit, and SPI allows for multiple bytes to be sent sequentially without interruption. This is achieved by keeping the CS line low throughout the data transfer, and the slave remains selected and continues to receive data.While data is being sent from the master to the slave via MOSI, data can simultaneously be sent from the slave to the master via MISO. This full-duplex nature of SPI enables efficient communication.MISO is used by slave devices to send data back to the master, often as a response to commands or queries (e.g., sensor readings and status updates). Some peripherals (e.g., displays, DACs) only receive data and lack MISO. In such cases, SPI operates with three wires (MOSI, SCLK, CS).Key ParametersClock polarity (CPOL) and clock phase (CPHA) are essential parameters in SPI protocol.Clock PolarityThe SPI clock can be idle low, or high.Idle Low (CPOL = 0): The clock signal is held at a low voltage level during idle state.Idle High (CPOL = 1): The clock signal is held at a high voltage level during idle state.Clock PhaseThe clock phase works with CPOL to define whether data is sampled on the rising or falling edge of the clock cycle.CPHA = 0: Data is sampled on the rising clock edge (relative to the idle state).CPHA = 1: Data is sampled on the falling clock edge.Four SPI modes are defined by the combination of CPOL and CPHA values, as shown in Fig. 2.Fig. 2. Four working modes of SPI based on the combination of CPOL and CPHA. Source: Journal of Physics Conference SeriesMode 0 (CPOL = 0, CPHA = 0): In this mode, the clock signal remains low during the idle state, and data sampling occurs on the rising edge.Mode 1 (CPOL = 0, CPHA = 1): In this mode, the clock signal remains low during idle, and data is sampled on the falling edge.Mode 2 (CPOL = 1, CPHA = 0): In this mode, the clock signal remains high during idle, and data is sampled on the falling edge.Mode 3 (CPOL = 1, CPHA = 1): In this mode, the clock signal remains high during idle, and the data is sampled on the rising edge.AdvantagesWith only four primary signal lines, SPI simplifies hardware design compared to more complex protocols like I2C. The SPI protocol enables serial communication where data is transmitted sequentially, one bit at a time, by using a minimal number of cables. It reduces hardware costs and complexity compared to parallel systems.SPI facilitates synchronous communication using a shared clock signal between the sender and receiver. It enables full-duplex communication where devices send and receive data simultaneously through separate lines. It supports configurable data widths, allowing up to 128 bits, which provides adaptability for various applications. It achieves high data rates, typically up to several Mbps or MHz.ApplicationsSPI is more commonly used in consumer electronics, particularly in low-power and cost-effective systems. It interfaces with sensors, displays, memory devices, ADC/DAC converters, real-time clocks, game controllers, wireless modules like Wi-Fi and Bluetooth, EEPROM, flash, digital signal processor, and a digital signal decoder facilitating efficient data exchange. The SPI protocol is more commonly used in wearables and IoT devices.Summarizing the Key PointsSPI is a 4-wire, full-duplex communication protocol that facilitates quick data exchange between microcontrollers and peripherals.The protocol utilizes four main signal lines: MOSI, MISO, SCLK, and CS, simplifying hardware design compared to more complex protocols like I2C.There are four SPI modes determined by clock polarity and clock phase, influencing data sampling and synchronization rates.Typical applications of SPI include interfacing with sensors, displays, memory devices, and wireless modules.ReferenceLiao, C., Yu, H., & Liao, Y. (2025). Verification of SPI protocol using universal verification methodology for modern IoT and wearable devices. Electronics, 14(5), 837. https://doi.org/10.3390/electronics14050837Qiang, J., Gu, Y., & Chen, G. (2020). FPGA implementation of SPI bus communication based on state machine Method. Journal of Physics Conference Series, 1449(1), 012027. https://doi.org/10.1088/1742-6596/1449/1/012027Rohde & Schwarz. (2023, April 12). Understanding SPI [Video]. YouTube. https://www.youtube.com/watch?v=0nVNwozXsIc

Overview: This article covers logic circuits in digital systems, focusing on combination circuits and encoders, their types, functions, and applications for efficient data processing. Logic circuits for digital systems may be combination or sequential.What is a combination circuit?A combination circuit is a memoryless digital circuit consisting of logic gates whose output is determined from only the present combination of inputs. It comprises an interconnection of basic logic gates NAND, NOR, or NOT gates to produce switching circuits.There are no feedback circuits in which changes to the input signal will immediately affect the output. They can be considered decision-making circuits that transform binary information with n inputs to required output data with m number of outputs. Common types of combination circuits includeAdderSubtractorComparatorMultiplexerDemultiplexerEncoderDecoderThe encoder-decoder structure is a popular approach in many deep learning applications, especially for sequence-to-sequence tasks. An overview of encoders is given in this article.What is an encoder?A binary encoder is a combinational circuit that converts information from  input lines into n-bit binary code. Only one input line is activated at a time, depending on which input is high, we get the specific code at the output.Types of EncodersThe most common types of encoders include4-to-2 Encoder8-to-3 Encoder (Octal Encoder)Decimal to BCD EncoderHexadecimal to Binary EncoderPriority Encoder4-to-2 EncoderConverts four input lines into two output lines, as shown in Fig. 1, applicable for data multiplexing and control signal generation. The block diagram of the 4-to-2 encoder is shown in Fig. 1, which converts = 4 input lines into n = 2 output lines.Fig. 1 Block diagram of 4:2 encoder. Source: Rakesh Kumar, Ph.D. Table. 1 Truth table of 4:2 encoder Source: Rakesh Kumar, Ph.D.DOD1D2D3XY100000010001001010000111 D0, D1, D2, and D3 are the input lines, and only one of these lines is active (1) at a time. X and Y are the output lines representing the binary code corresponding to the active input.The logical expression of 4:2 encoder can be derived from the truth table  asX = D2 + D3Y = D1 + D3The logic circuit of the 4:2 encoder can be implemented with the help of the OR gate, as shown in Fig. 2Fig. 2 Logic circuit diagram of 4:2 encoder. Source: Rakesh Kumar, Ph.D.8-to-3 Encoder (Octal Encoder)The octal encoder converts eight input lines into three output lines, often used for octal to binary conversion. The block diagram of the 8-to-3 encoder, in which it converts = 8 input lines into n = 3 output lines, is shown in Fig. 3.Fig. 3 Block diagram of 8:3 encoder. Source: Rakesh Kumar, Ph.D. Table. 2 Truth table of 8: 3 encoder. Source: Rakesh Kumar, Ph.D. DOD1D2D3D4D5D6D7XYZ1000000000001000000001001000000100001000001100001000100000001001010000001011000000001111 The logical expression of 8:3 encoder can be derived from the truth table asX = D4 + D5 + D6 + D7Y = D2 + D3 + D6 + D7Z = D1 + D3 + D5 + D7The logic circuit of the 8:3 encoder can be implemented with the help of the OR gate, as shown in Fig. 4Fig. 4 Logic circuit diagram of 8:3 encoder Source: GeeksforGeeksDecimal to BCD Encoder:Decimal to BCD encoder converts decimal numbers (0–9) into 4-bit Binary-Coded Decimal (BCD).Hexadecimal to Binary EncoderIt converts 16 input lines into four output lines, which is useful for hexadecimal to binary conversion.Priority EncoderA priority encoder is a unique encoder that prioritizes the input with the highest priority when two or more inputs are high simultaneously. The block diagram of the 4:2 priority encoder is shown in Fig. 5.Fig. 5 Block diagram of 4:2 priority encoder Source: Rakesh Kumar, Ph.D. Table. 3 Truth table of 4:2 priority encoder Source: Rakesh Kumar, Ph.D.DOD1D2D3XY100000X10001XX1010XXX111 The logic expression of the priority encoder can be derived from the truth table asX = D3 + D2Y = D3 + D2’D1AdvantagesBinary encoders encode input information into a compact code, effectively reducing the number of bits required to represent the input data. They enable efficient data handling in digital systems. Their ability to reduce the required input/output (I/O) pins makes them invaluable when connecting numerous input devices to microcontrollers or processors.To conclude, encoders are a significant component for many applications, including encoding data for transmission, providing motion feedback for robotics and machinery, converting user actions to digital signals, data multiplexing, and signal generation.Summarizing the Key PointsCombination circuits in digital systems consist of logic gates that produce outputs based on current input combinations without memory of past inputs.Encoders are essential in converting multiple input signals into a compressed binary code, significantly reducing electronic systems' required output lines.Priority encoders prioritize the highest active input when multiple signals are high, ensuring reliable data processing.ReferenceKalamani, C., Murugasami, R., Usha, S., & Saravanakumar, S. (2023). Design of encoder and decoder using reversible logic gates. Measurement Sensors, 31, 100989. https://doi.org/10.1016/j.measen.2023.100989Sofeoul-Al-Mamun, M., Miah, M. B. A., & Masud, F. A. (2017). A novel design and implementation of 8-3 encoder using Quantum-Dot Cellular Automata (QCA) technology. European Scientific Journal ESJ, 13(15), 254. https://doi.org/10.19044/esj.2017.v13n15p254Singha, T. B., Konwar, S., Roy, S., & Vanlalchaka, R. H. (2014). Power efficient priority encoder and decoder. International Conference on Computer Communication and Informatics, 1–5. https://doi.org/10.1109/iccci.2014.6921806ALL ABOUT ELECTRONICS. (2022a, May 1). Encoder in Digital Electronics | Working, application and Logic circuit of Encoder [Video]. YouTube. https://www.youtube.com/watch?v=NWiPVMDh7GEALL ABOUT ELECTRONICS. (2022, May 13). Priority Encoder Explained (with Simulation) | 4 to 2 Priority Encoder | 8 to 3 Priority Encoder [Video]. YouTube. https://www.youtube.com/watch?v=gnoqn705LBg

Overview: This article examines the shift from relay systems to programmable logic controllers in industrial automation, highlighting their key components, workings, and advantages to improve accuracy in control systems across various industries.The trend of automating mechanical and electrical systems in industrial facilities and commercial buildings is advancing rapidly. Before, industrial automation relied heavily on relay-based control systems. These systems were primarily composed of banks of relays, which were electromechanical switches that opened and closed circuits in response to electrical signals.Relay systems presented several significant challenges, including complex wiring for inputs/outputs, making changes time-consuming. Additionally, the size of relay banks is relatively larger, consuming significant floor space and complicating maintenance efforts.The development of solid-state electronics and microchips allowed the command logic of relay-based systems to be replaced with software logic, leading to the rapid adoption of Programmable Logic Controllers (PLCs).What is a PLC?A Programmable Logic Controller is a special-purpose small computer that is an important part of control systems, converting data from sensors and other field devices into values that may operate devices. A PLC carries out pre-programmed actions or outputs such as arithmetic, counting, sequencing, logic, and timing based on inputs and a set of specific rules.Key Components and Working of PLCThe primary components of a PLC, as shown in Fig. 1, includeHardwareProgrammingFirmwareFig. 1 Key components of programmable logic controller Source: MDPIHardwareThe hardware component comprisesInput module: Input modules receive signals from sensors and convert them into a format the PLC can understand. These modules provide the physical connections between a PLC and the external world. They come in two primary types: digital (whether a device is in an on or off state, with no intermediate values) and analog (range of values, providing continuous data that reflects real-world conditions).The input module receives signals from process devices and converts the incoming signal to voltage, which the PLC can use. An isolator block is used to electrically isolate or protect the PLC from fluctuations in the input voltage/current signal. It sends the processed signal to the CPU for further processing.Central processing unit: The CPU is the brain of the PLC that processes input signals from sensors and devices connected to the PLC. It generates output signals based on the programmed logic to control actuators, motors, valves, and other devices. Integrated circuits, such as Modbus and LAN connections, enable remote communication for reprogramming or monitoring.Memory unit: This unit stores the PLC program and data necessary for operation. The two main components of PLC's small memory capacity are system memory configured with the CPU and user memory to store user programs.Power module: The power supply module provides the necessary electrical power to the PLC and its components even in harsh industrial environments where voltage fluctuations are common.Output module: Output modules send signals from the PLC to actuators and other devices to control their operation. These modules execute commands based on the logic defined in the program.Communications module: This module enables communication between the PLC and other systems, such as HMIs (Human-Machine Interfaces), other PLCs, or supervisory control systems.ProgrammingPLC programming involves developing a set of instructions that dictate how the PLC should monitor inputs, process data, and control outputs in an industrial automation process. It uses any of five standard languages defined by the IEC 61131-3 standard, which includeLadder Diagram (LD): LD is a graphical language created to replicate hard-wired relay logic.Structured Text (ST): ST is a textual language that is identical to the BASIC programming language.Sequential Function Chart (SFC): SFC is a graphical language that resembles a flow chart.Function Block Diagram (FBD): FBD is a graphical language that utilizes blocks to illustrate data flow. Logic functions, math functions, schedules, and proportional-integral-derivative (PID) control are all included in the blocks.Instruction List (IL): This is a low-level text-based programming language used for PLC.FirmwarePLC firmware serves as the operating system, governing the PLC's interactions and data exchange with the physical environment. It acts as a bridge between the hardware and software. Firmware interprets code into binary signals influencing inputs, outputs, internal flags, registers, and network communications.AdvantagesPLCs also eliminate the need for complex and expensive wiring. They are simple to replace if they fail, reducing intermission time and production losses.PLCs enable real-time process control, which increases the accuracy of operations and significantly reduces the risk of human errors.PLCs can be easily programmed and reprogrammed to adapt to changing process requirements without the need to rewire the control cabinet.PLCs are designed for rigorous industrial work, offering superior longevity and typically serving for 20 to 30 years.PLCs are designed to be user-friendly and simple to program and monitor using a graphical user interface (GUI) or other software.They are easily expandable by adding more modules and replacing them whenever more I/O capacity is neededApplicationsPLCs are employed in commercial and industrial applications, such as automation, robotics, and smart technologies, to automate processes with minimal, and sometimes even zero, manual intervention. The operation can range from simple on/off control based on the status of inputs to more advanced responses based on calculations, sequences, and logic.PLCs are used in a wide range of industrial automation applications, including the manufacturing industry, oil and gas power generation, water and wastewater treatment, transportation, etc.Summarizing the Key PointsThe transition from relay-based control systems to PLCs has revolutionized industrial automation, simplifying wiring and enhancing efficiency in control processes across various sectors.PLCs serve as special-purpose small computers in control systems, converting sensor data into digital values to execute pre-programmed tasks, thereby improving operational accuracy and reliability.Key components of PLCs include input/output modules, a central processing unit, memory, and communication interfaces, all working together to enable efficient data processing and control.ReferenceYao, K., Lin, C., & Pan, C. (2024). Industrial Sustainable Development: The development trend of Programmable Logic Controller technology. Sustainability, 16(14), 6230. https://doi.org/10.3390/su16146230Wang, Z., Zhang, Y., Chen, Y., Liu, H., Wang, B., & Wang, C. (2023). A survey on programmable Logic controller vulnerabilities, attacks, detections, and forensics. Processes, 11(3), 918. https://doi.org/10.3390/pr11030918Walters, E., & Bryla, E. (2016). Software Architecture and Framework for Programmable Logic Controllers: A Case Study and Suggestions for research. Machines, 4(2), 13. https://doi.org/10.3390/machines4020013

Overview: This article explores FinFET technology, detailing its structure, working principles, types, and advantages in modern semiconductor design, highlighting its impact on performance and miniaturization. Over decades, transistors have greatly reduced in size from millimeters to tens of nanometers, allowing for greater functionality within microchips, which results in increased density and speed. A MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistors) is a type of transistor with four terminals: the Gate (G), Source (S), Drain (D), and Body (B), as shown in Fig. 1. The gate is the control terminal, while the source and drain are the terminals through which charge carriers enter and exit the channel. When a voltage is applied to the gate terminal, it creates an electric field that influences charge carriers in the substrate, and current flows from the source to the drain. Fig. 1 Diagrammatic illustration of a structure and working of MOSFET. Source: Rakesh Kumar, Ph.D. The amount of current flowing through this channel is controlled by varying the gate voltage. Additionally, when the length (L), depicted in Fig. 1 of the gate electrode is reduced, the control of the gate over the channel region is also reduced, which lowers the transistor performance. However, the short-channel effect is one of the important challenges of miniaturization. When the channel length is reduced to a point where it becomes comparable to the depletion layer widths of the source and drain junctions, the electrical characteristics of the device are impacted. Several other challenges include gate-induced drain leakage, diminished low power performance, threshold voltage shifts, etc. Overcoming Challenges with Miniaturization of Transistors Multi-gate field-effect transistors (MuGFETs) have emerged as an advancement in overcoming the limitations of traditional MOSFETs. This design minimizes short-channel effects by enhancing gate control over the channel region, which is important as devices scale down to sub-20 nm nodes. The most common type of MuGFET includes Fin Field-Effect Transistors. FinFET FinFET, or Fin Field-Effect Transistor, is an advanced type of MOSFET characterized by its three-dimensional structure where the channel forms vertical "fins" for enhanced electrical performance. This non-planar transistor design addresses the limitations of traditional planar MOSFETs. The FinFET design incorporates multiple gates that wrap around the channel, as shown in Fig. 2, providing improved electrostatic control over the channel. This configuration significantly reduces leakage currents and enhances drive current capabilities. Fig. 2 A comparison of the structure of a)MOSFET and b) FinFET Source: MDPI Structure of FinFET The channel is formed by thin vertical fins made of semiconductor material, typically silicon. These fins extend upwards from the substrate, providing a larger effective channel area for current flow. The gate wraps around the fins on three sides (in tri-gate configurations), allowing superior electrostatic control over the channel. A silicon dioxide layer (SiO₂) acts as an insulator between the gate and the channel, preventing direct electrical contact and enabling the gate to influence the channel’s conductivity through an electric field. The substrate is the base for the entire structure and can be either bulk silicon or silicon-on-insulator (SOI). The lightly doped p-type substrate supports the fins and helps isolate individual devices on a chip. Working of FinFET When a positive voltage is applied to the gate of an n-channel FinFET, it generates an electric field that attracts electrons from the source region to form an inversion layer in the p-type substrate beneath the gate oxide. As the gate voltage exceeds a threshold (threshold voltage), this inversion layer allows current to flow between the source and drain. The channel formed by this inversion layer provides a conductive path for charge carriers. Current flows from the source to the drain when a voltage is applied across these terminals. The amount of current flowing through this channel can be controlled by varying the gate voltage. If the gate voltage is below the threshold, no channel forms, resulting in no current flow (cutoff region). As voltage increases further, the current reaches saturation and stabilizes. Types of FinFET FinFETs may be divided into two primary groups according to the thickness of their dielectric, as shown in Fig. 3 as Double-gate FinFETTri-gate FinFET Double-Gate FinFET A double-gate FinFET features a single-gate electrode that controls the channel from two opposite sides of the fin (front and back). This design is enhanced with a dielectric layer positioned above the fin, often called a hard mask. This layer inhibits the electric field from affecting the top of the fin, thereby preventing parasitic inversion channels at the corners of the fin. Tri-Gate FinFET In contrast, a tri-gate FinFET has a single gate electrode that wraps around three sides of the fin. This allows full control over the channel from three directions without any dielectric layer inhibiting the electric field above the fin. Double-gate and tri-gate FinFET are known for their lower parasitic capacitance, less complex structure, and manufacturing process. Fig. 3 Illustration of types FinFET a) Double-gate and b) Tri-gate FinFET. Source: MDPI One of the advanced transistor architectures that enhances control over the channel by surrounding it with a gate on all sides is a gate all around FET. Gate-all-around FET Gate-all-around FET (GAA-FET) has improved gate coupling and enables precise channel tuning and lower short-channel effects. Unlike FinFETs, where the gate wraps around the channel on three sides, GAAFETs surround the channel on all four sides, as shown in Fig. 4. This provides superior electrostatic control over the channel, significantly reducing leakage currents and enhancing performance. Fig. 4 Diagrammatic illustration of the structure of MOSFET, FinFET, and Gate all around FET. Source: Semiconductor Engineering   Among gate-all-around FinFET topologies, nanosheets, as shown in Fig. 5, offer more "on" current and improved electrostatic control than FinFETs. In contrast, nanowires offer the greatest electrostatic control among various structures. There are two primary forms of FinFET technology based on structural and functional characteristics, as shown in Fig. 6, which are Bulk FinFETsSOI (silicon on insulator) FinFETs Fig. 6 Illustration of FinFET types a) Bulk FinFETs b) SOI (silicon on insulator). Source: MDPI Bulk FinFETs These FinFETs are built on bulk silicon and use fins etched directly onto the silicon substrate. They can perform well in sub-20 nm technology nodes while maintaining effective electrostatic control. The transition from planar MOSFETs to Bulk FinFETs is a relatively simple procedure because Bulk FinFETs closely resemble the traditional planar MOSFET structure. SOI (silicon on insulator) FinFETs These FinFETs are constructed on a silicon-on-insulator substrate, physically isolated fins that do not come into direct contact, allowing for better device isolation. Due to their reduced substrate coupling effects, SOI FinFETs can reduce parasitic capacitance and improve performance in high-speed applications. Applications FinFETs have a unique 3D structure and enhanced electrostatic control. In biosensing, they excel at detecting biomolecules like DNA and proteins through various configurations, including negative capacitance and junctionless designs, making them valuable for medical diagnostics. Their chemical sensing capabilities are used in gas detection (particularly H₂ and PH₃), pH measurement, and ion sensing, with specialized designs like ion-sensitive floating gate FinFETs achieving high sensitivity. In physical applications, they've found great use in temperature sensing, especially in quantum computing, where bulk FinFETs operating in the Coulomb blockade regime provide precise temperature measurements in cryogenic environments. Summarizing the Key Points FinFETs enhance transistor performance by minimizing short-channel effects, improving electrostatic control, and reducing leakage currents, which are important for sub-20 nm technology nodes in microchips.Gate-all-around FETs improve gate coupling and channel tuning, offering superior control over short-channel effects compared to traditional FinFET designs and enhancing overall device performance.The transition from planar MOSFETs to FinFETs represents a significant advancement in semiconductor technology, enabling higher density and speed in microchips while addressing miniaturization challenges. Reference Karimi, K., Fardoost, A., & Javanmard, M. (2024). Comprehensive review of FinFET Technology: history, structure, challenges, innovations, and emerging sensing applications. Micromachines, 15(10), 1187. https://doi.org/10.3390/mi15101187 Madhavi, K. B., & Tripathi, S. L. (2020). Strategic Review on different materials for FinFET Structure Performance Optimization. IOP Conference Series Materials Science and Engineering, 988(1), 012054. https://doi.org/10.1088/1757-899x/988/1/012054 Review on Fin Shape Channel Field Effect Transistor (FinFET)-Journal of Electronics Electromedical Engineering and Medical Informatics Gate-All-Around FET (GAA FET)-Semiconductor Engineering GAA Structure Transistors- Samsung