Happy Thanksgiving!

To allow our hard-working office staff the ability to spend time with their families during Thanksgiving week, we are closing our office from Monday, November 20 – Friday, November 24. During this time, we will still be shipping orders but phones will not be answered and emails will not be responded to until Monday, November 27th.

We eagerly anticipate serving you again when we reopen on Monday morning, November 27, ready to assist with your electronic component needs. Wishing you a joyous and peaceful Thanksgiving!

West Florida Components Thanksgiving week office hours

Difference Between Power and RF Inductors

In many electronic designs, we have components that consist of only several turns of a wire, with or without a core. These components are inductors. It is customary to find them in many types of electronic devices, including voltage and power conversion circuits to high-frequency microwave and RF circuits. Typically, inductors resist any change in the current flowing through them, by producing an electromagnetic field.

Available in a variety of package styles depending on their current ratings, inductors are essential components in electronic designs. They function as filters, chokes, and impedance-matching functions. For a practical application, it is essential to understand the important performance parameters of inductors.

Any inductor, whether used for power or RF applications, has the same performance parameters. These include the inductance value, its tolerance, current rating, its DC resistance, SRF or self-resonant frequency, Q or quality factor, and temperature range. However, specific applications may stress more on some of these performance parameters as they have more relevance for that application. For instance, an application involving RF frequencies may give more importance to Q and SRF parameters rather than to the current rating, which is more important for power applications.

The size of an inductor—how big or how small it can be—is usually dependent on the inductance value, its current carrying capacity, and acceptable losses. These are critical parameters when selecting inductors. Selecting an inductor usually begins with the inductance value, typically in nH or in mH, and depends on its function in the circuit. Associated with the nominal inductance value is its tolerance, in %, characterizing the amount of variation of the inductance value, and is determined by the application.

For instance, RF applications typically require inductances closely matched by precise inductance values, and with tight tolerances, such as ±2%. On the other hand, power applications may use inductors with inductance values within a larger band, and with wider tolerances, such as ±20%.

Another important parameter for inductors is their ability to handle current, which can vary greatly by application. This is specifically true for inductors in power circuits such as DC-DC converters, where the current values can change widely, with very high peak-to-average current ratios. Inductors selected on the basis of the application’s highest instantaneous current value may provide an inductor much larger than necessary. On the other hand, selecting an inductor based on the average current value in the circuit may lead to a small inductor resulting in inconsistent performance during peak current deliveries.

The quality of an inductor has more relevance in RF circuits than it has for power applications. Quality or the Q factor is a dimensionless parameter that characterizes the inductor’s bandwidth relative to its center frequency. High Q values are typically matched to narrow bandwidths and low losses, more critical in RF applications.

For power applications, the losses in inductors are more important. Here, the DC losses, characterized by the resistance of the wire, are rather more relevant. Therefore, inductors for power applications tend to be made of wires with larger diameters, so as to increase the area for current travel and thereby reduce the resistance.

Difference Between Chokes and Inductors

Industries typically use chokes and inductors for altering, filtering, and delivering electrical current. However, for using these devices effectively for machinery and devices that rely on electrical power, it is essential to understand the difference between chokes and inductors, as the design of these electrical components must meet specific applications’ requirements.

Despite a choke being a type of inductor, it has a design, functionality, and application that sets it apart from other inductor designs. Physically, this electrical component looks like a donut-shaped core and has an insulated wire wrapped around it.

As its name implies, primarily, a choke restricts or cuts off high-frequency components from alternating currents flowing through it. It allows only low-frequency currents, including direct currents to pass through. Therefore, a choke eliminates most of the high-frequency currents and allows only low-frequency and DC currents to pass through to the load.

Another function of the choke is its ability to restrict a steep rise and fall of current and voltage in circuits. A fast rise in voltage can damage insulation. Conversely, a choke can also generate high voltages such as those necessary to strike an arc for starting fluorescent tubes.

On the other hand, inductors primarily store electrical energy as a magnetic field when current passes through them. For this purpose, inductors typically have a magnetic core wrapped with an insulated coil. Therefore, all chokes are inductors, but the reverse is not true—not all inductors are chokes. Many technologies use inductors for various functions.

For instance, inductors are necessary to filter a band of frequencies by increasing the impedance for these frequencies. Inductors also act as proximity sensors without making physical contact, as the magnetic fields of the inductor and the object can interact. Multiple inductors, using the same magnetic field, constitute a transformer that can effectively transform, or step-up or step-down voltages. Inductors typically arranged circularly around a motor shaft, can interact with other stationary inductors to provide the torque necessary to rotate the motor shaft. Switching power supplies use inductors to temporarily store and supply electrical energy in and from their magnetic fields.

An inductor has a much wider functionality as compared to a choke. For instance, an inductor acts as a choke when filtering high-frequency signals. While the choke’s primary function is to remove high-frequency signals and allow low-frequencies and DC signals to pass through, the primary function of an inductor is to store energy in its magnetic field.

In RF circuits, a choke typically protects against the ingress of high-frequency signals, assuring operational stability. On the other hand, an inductor, in parallel or in series with a capacitor can act as a tuned circuit. Such tuned circuits allow the RF circuit to oscillate at a specific band of frequencies as determined by the inductor and capacitor combination.

Both chokes and inductors are critical in circuits that must conform to EMI/EMC or electromagnetic interference and compatibility standards. They block the generation and reception of unwanted signal frequencies in equipment. They prevent the electromagnetic spectrum of the device from increasing beyond a specified level as directed by the standards.

Gate-Drive and Isolation Transformers

Controlling the current flow between the drain and the source of a MOSFET requires the application of a drive voltage to the gate of the MOSFET. Switching power supplies operate the MOSFET as a current switch by applying a pulsed voltage drive to the gate for turning the drain-source current on and off. Delivering the controlling pulse requires a gate drive transformer to provide isolation between the controlling drive circuit and the MOSFET. Companies like Coilcraft offer off-the-shelf gate drive transformers for the purpose.

Gate drive circuits must provide an isolated or floating bias supply for maintaining the necessary turn-on bias when the MOSFET source rises to the input voltage. While driving the MOSFET gate, not only does the gate drive transformer help in isolating the controlling gate drive circuit from the switch node, it may also scale the output voltage via a suitable turns-ratio between its primary and secondary.

Some applications use optocouplers or digital isolators for driving the MOSFET directly. However, the use of a gate drive transformer is preferable, as it can provide a higher voltage requirement, much lower turn-on and turn-off delay times, and it can scale voltages by the ratio of its turns. These advantages make the simple gate driver transformer the best-performing solution for high-frequency and high-voltage applications that require maintaining accurate and fast signal timing.

Typical low-power applications use a simple single-output, transformer-coupled, high-side gate driver circuit. Additional components like capacitors, resistors, and diodes may be necessary depending on the duty cycle and other circuit conditions. These include preventing the development of a DC voltage across the transformer, as this may cause it to saturate. The additional components also help in the coupling capacitance and magnetizing inductance from resonating with specific duty cycle ratios. For single-ended circuits, the highest duty cycle is preferably 0.5.

Higher power applications may require half-bridge and full-bridge configurations coupled with transformers. Double-ended or DC-coupled bridge configurations may use a theoretical maximum duty cycle of 1.0. Designers use isolation transformers for isolation and voltage scaling in power supply applications. These serve three main purposes.

First, the transformer helps to connect circuits with grounds at different potentials—this prevents ground loop formation. Second, the transformer provides galvanic isolation, thereby preventing any flow of direct current. Lastly, the transformer provides voltage transformation—stepping up or stepping down from one voltage to another.

Isolation transformers may be available as signal transformers, power-supply transformers, communication transformers, data-line transformers, and many others. These are versatile and aptly suited for several industrial and commercial data communications and power supply applications.

Using off-the-shelf gate drive and isolation transformers can simplify the design of the gate drive circuit and significantly reduce the design cycle time. Coilcraft transformers typically use high-permeability ferrite cores for maximizing the inductance and minimizing the magnetizing current.

The designer can determine the required transformer size by the volt-time product of the application. This forms the first selection criterion for a gate drive transformer, as the designer can select the appropriate volt-time or V-µsec rating from the datasheet of the transformer. The rating must be equal to or greater than the highest applicable voltage-time product 

Modern RTD-Based Sensors

The popular belief is to not fix things that aren’t broken. The idea is to not tamper with something performing reliably and proving its worth. This advice aptly applies to circuit designs using RTD sensors that efficiently and quietly measure temperature in industrial manufacturing facilities worldwide.

However, in meeting the requirements of Industry 4.0, where smart factories are the norm, it is now evident that the current RTD sensors in use are not fitting the purpose. Automation engineers today want industrial temperature sensors to be of smaller form factors, flexible with communications, and capable of remote reconfigurability. Incumbent solutions, sadly, are unable to support them. However, it is possible to easily redesign these sensors to equip them with the necessary features to meet the new industrial design.

The RTD industrial temperature sensor translates temperature, a physical quantity, into an electrical signal. The typical range of such sensors is between -200 °C and +850 °C, with a highly linear response across it. RTDs commonly use metal elements like copper, nickel, and platinum. Among these, PT1000 and PT100 platinum RTDs are the most popular. While an RTD can use either two, three, or four wires, the 3-wire and 4-wire versions are the most popular. Being passive devices, RTDs require an excitation current for producing an output voltage. A voltage reference generates this current, with an operational amplifier acting as a buffer for driving the current into the RTD, which produces an output voltage signal varying in response to changes in temperature. The voltage signal may vary from tens to hundreds of millivolts depending on the type of RTD in use and the measured temperature.

An AFE or Analog Front End conditions and amplifies the low amplitude voltage signal from the RTD before the ADC or Analog to Digital converter digitizes it. A microcontroller runs an algorithm over the digitized signal, compensating for any non-linearity in it. The microcontroller then sends the processed digital output to a communications interface for transmission to a process controller. A typical implementation of the AFE is by a signal chain of components with each performing a dedicated function.

This discrete approach requires a large PCB or printed circuit board for accommodating all the ICs and power and signal routing, setting a minimum size for the sensor enclosure. Rather, modern RTD-based sensors use a superior and more minimal approach—the AD7124-4, an integrated AFE.

The AD7124-4 is a compact IC in a single package. It includes a multiplexer for accommodating multiple-wire RTDs, a voltage reference, a programmable gain amplifier, and an ADC using the sigma-delta operating principles. The IC has the capability to provide the necessary excitation currents for the RTD. The entire arrangement effectively replaces five of the signal-chain components from the traditional setup. Not only does this significantly reduce the amount of board space necessary, but it also enables the sensor to use a much smaller enclosure.

Next comes the communications interface. Modern RTD-based sensors typically use the IO-Link which eliminates the use of expensive ASICs for implementing specific network protocols. IO-Link is a 3-wire industrial communications standard for linking sensors and actuators with all industrial control networks.

Software Defined Electric Vehicles

Around the world, SDVs or software-defined vehicles are one of the two trends driving the design of new vehicles, the other being EVs or electric vehicles. As a result, vehicle design is undergoing a major transformation. From features and capabilities that were so far defined by hardware, they are now changing over to those being defined by software. This opens up newer opportunities resulting in agile developments, fast and continual improvements, and remote maintenance.

SDVs are ushering in a new approach to the development of vehicles. In turn, that is enabling improvements in the vehicle over time, based on in-depth access to the vehicular data in real time. Cloud processing and machine-learning training is leading to updates over the air for improving the software and related machine-learning models. Along with this continuous deployment and integration, engineers are able to use model-based design tools more effectively for improving and developing software algorithms that, in turn, help to run the vehicles more efficiently.

As a result, carmakers over the world are investing hugely in vehicle electrification for helping to reduce greenhouse gases. They are offering their customers vehicles with acceptable driving ranges along with easy access to charging stations. Many are committing to transitioning their fleets from ICE or internal combustion engines to EVs over the next decades. This is resulting in the swift deployment of EVs. Furthermore, the effect of this shift to a more software-centric and electric future is bringing newer challenges to the automobile industry.

The major beneficiary of this change is the EV motor. With the industry moving to the SDV approach, there is faster access to vehicular data that can monitor the aging and performance of the EV motor. Powerful automotive microcontrollers now support newer features over time, while the deployment of software upgrades is available through wireless updates. This makes the software-defined EV motor a dynamic product that keeps evolving and improving over time. It takes advantage of in-vehicle data in real-time, supporting cloud development along with enhancing features.

Changing over to a software-defined EV motor design affects all the stages of development of the control systems of the EV motor. Not only does this enable faster cycles of development, but also helps enhance the performance, while monitoring for maintenance needs, thereby extending the system’s lifetime.

High-level modeling tools are the trend in motor control design. Designers use modeling tools like Simulink and MATLAB for concentrating on using their key expertise in controlling the EV motor and systems, rather than on programming. This is because modeling tools operate at the algorithm level, where the designers can optimize them to improve vehicular performance and efficiency.

Using modeling tools results in three significant advantages—flexibility, safety, and speed. Designers use modeling tools to test algorithms and quickly analyze software, rather than depend on evaluation through hardware integration. Not only does this bring in flexibility, but also speed when designing the control module of EV motors. For designers, developing at the algorithm level is especially useful when developing strategies for the smooth control of a motor.

Miniature Temperature Sensors

During the COVID19 pandemic, it became necessary to use quick and non-invasive techniques for assessing body temperature. Various locations that included airports, hospitals, schools, and shopping centers used non-contact thermometry. This essentially employs an infrared sensor for measuring the surface temperature but without any physical contact. Not only was this technique very popular, but it is now a typical way of taking body temperature. While providing quick and reliable readings, infrared thermometers are also non-invasive.

The accuracy of infrared thermometers largely depends on variables such as the nature of the surface it is measuring and its surroundings. However, Melexis Microelectronic Integrated Systems has now successfully resolved these problems. They have developed a miniature infrared temperature sensor that offers medical-grade accuracy and temperature compensation.

Melexis specializes in and offers several microelectronic ICs and sensors for various applications. Their sensors are applicable to consumer, automotive, digital health, energy management, and smart device industries. Samsung has deployed one of the Melexis products in their GWS smartwatch series. This is the medical-grade version of the MLX90632 temperature sensor, which operates on FIR or far-infrared technology. The enhanced accuracy of the MLX90632 temperature sensor along with its non-contact temperature measurement technique allows its use for menstrual-cycle tracking. A wide range of new and possible applications in health, sports, and other domains is now possible because of the reliable continuous temperature measuring capabilities of the sensor.

The MLX90632 FIR temperature sensor is an SMD or surface mount device that measures the infrared radiation from the object for reporting the temperature. As the sensor has a tiny SMD packaging, it is suitable for use in a variety of applications, especially in wearables, hearables or in-ear devices, and point-of-care clinical applications. All these applications require high accuracy for measuring the human body temperature.

In comparison to traditional contact methods of measuring temperature, the non-contact temperature measurement methods offer advantages, primarily as they enable sensing and measuring the temperature without directly touching the measured surface or object. This is helpful in specific circumstances where it is undesirable to make physical contact with the object, especially when the object may be fragile, under movement, or located in a hazardous area. When a quick response is necessary, or there is no guarantee of good thermal contact between the object and sensor, a non-contact temperature measurement technique is more accurate. It can also yield better and more reliable results as compared to what the contact temperature measurement techniques can.

The MLX90632 sensor is a minuscule device in a chip size of 3 x 3 x 1 mm QFN package. Within this tiny space, it incorporates the sensor element, the signal processing circuitry, digital interfacing circuitry, and optics. The small size enables quick and easy integration within a huge range of modern applications, typically with limited space.

Melexis calibrates its sensors in-house, thereby ensuring high accuracy. They compensate for harsh external thermal conditions with internal precautions for electrical and thermal operations. After amplifying and digitizing the voltage signal from the thermopile sensing element, the IC filters it digitally and stores the raw measurement data in its RAM. This is accessible via an I2C interface.

MCUs Working Sans Batteries

Nature is exceptionally efficient. It maximizes available and additional resources by using as much of it as possible. Humans are now beginning to follow in nature’s footsteps. Doing this allows us to improve performance, thereby reducing waste and minimizing cost. One of the methods in use today is energy harvesting. We can power electrical devices using ambient energy. For devices operating on batteries, it is possible to use energy harvesting for extending the useful life of the battery, or even replace the energy contribution of the battery entirely.

We have ultra-low-power microcontroller units or ULP MCUs as the logical choice for demonstrating energy harvesting. Many devices like wireless sensors, wearable technology, and edge applications use ULP MCUs because it is essential for these devices to extend their battery lives. Reviewing the working practice of energy harvesting is important to understand its value to ULP MCUs.

The principles of energy harvesting are simple. It must overcome the finite nature of the primary source of energy, here, the battery. However, as no process can be one hundred percent efficient, there will be losses when converting the source power to usable energy, even when there is boundless ambient energy available for capture. This is evident in wind turbines, a renewable large-scale energy source. The wind provides the turbines with potential energy, making the blades rotate. This movement turns a generator, producing electrical power. Other similar large-scale ambient energy sources also exist—geothermal heat, oceanic waves, and solar.

Wearables and other similar small-scale devices harvest thermal, kinetic, or environmental electromagnetic radiation energy. However, each of these makes use of different mechanisms for converting the source power to useful usable energy. It is necessary to consider the utility and practicality of each conversion mechanism, as the application defines the size and mass of the energy conversion technology.

For instance, making use of thermal radiation is more suitable for wireless sensor applications, as the sensor placement and design can take advantage of both forms of energy. Likewise, vehicles can use sensors that make use of radiant heat emanating from the road surface. As engine components like wheels are high-vibration locations, it is possible to harvest motion energy from near them. For wearables using ULP MCUs, harvesting the kinetic energy from the human user’s motion provides the most practical means of conversion to usable energy.

In wearable technology, the primary application of the ULP MCU is to process the edge data gathered by the sensor. And, it is critical to process this data with the minimum power consumption. Energy harvesting supplements the power from the battery, which has a finite amount of energy, and requires periodic replenishment in the form of recharging or replacement as its power depletes. There are three ways of capturing energy for ULP MCUs—using piezoelectric, electromagnetic, or triboelectric generators.

Kinetic forces compressing piezoelectric materials can make it generate an electric field, which can add as much as 10 mW to the battery. Harvesting energy from electromagnetic radiation like infrared, radio, UV, and microwaves can contribute about 0.3 mW of harvested power. Triboelectric generators use friction on dissimilar material surfaces rubbing together from mechanical movements like oscillation, vibration, and rotary motions to generate 1-1.5 mW of electricity.

Improving Power Management Efficiency

Design engineering teams face considerable challenges handling conflicting requirements for portable types of medical devices. Most of these devices are always-on types and must be capable of managing battery life with maximum efficiency and effectiveness. They also must have suitable dimensions tailored to the patient’s comfort, especially as most of these are meant to be worn 24 hours a day. Therefore, not only must their construction be robust, but they must also deliver the highest levels of performance. Designers use PMICs or power management integrated circuits for optimizing the power utilized by the ultra-low architecture, improving the sensitivity of measurements, and keeping the SNR or signal-to-noise figures on the high side.

Wearable technology is benefitting from the growing popularity of mobile networks from the perspective of both, the healthcare and the consumers. Although their design was initially meant for sports and wellness, the medical market is now finding increasing use for wearables. As a consequence, newer generations of medical wearable devices are available using MEMS or micro-electromechanical system sensors, including heart-rate monitors, gyroscopes, and accelerometers. Other sensors are also in use, such as for determining skin conduction and pulse variability. However, the more sensitive the sensor, the more it faces SNR issues so designers need to use better noise reduction techniques along with more efficient energy-saving solutions.

For instance, the accuracy of optical instruments depends on many biological factors. Therefore, design engineers maximize the sensitivity of optical instruments by improving their SNR over a wide range. They use voltage regulator ICs with low quiescent currents along with elements that improve the SNR by reducing ripple and settling times.

Maxim offers a complete SCODAS or single-channel optical data acquisition system, the MAXM86161. They have designed its sensor module for use in in-ear and mobile applications. They have optimized it for SPO2 or oxygen saturation in the blood, HR or reflective heart rate, and continuous monitoring of HRV or heart rate variability. There are three high-current programmable LED drivers on the transmitter part of the MAXM86161. While the receiver part has a highly efficient PIN photo-diode along with an optical readout channel. It features a low-noise signal conditioning ALE or analog front end. It includes a 19-bit ADC or analog to digital converter, a high-performance ALC or ambient light cancellation circuit, and a picket fence type detect-and-replace algorithm.

Optimizing the energy efficiency of an optical measuring instrument is a constraint on its design. Rather than use regular LDO or low-drop-out regulators, designers now use novel switching configurations to improve the efficiency further. The requirement is that the voltage regulation element provides a low level of ripples at high frequencies so that there is no interference when measuring heart rates. To operate LEDs at voltages different from what the Li-ion batteries can supply, designers use new buck-boost converter technologies, thereby curbing energy consumption and saving board space. For instance, they use the SIMO or single-inductor multiple-output buck-boost architecture for reducing the number of inductors and ICs the circuit requires.

The MAXM86161 from Maxim Integrated is a PMIC or power-management integrated circuit and is meant for applications that are space-constrained and battery-powered, where the efficiency must be high within a small space.

Modular Machine Vision

As the AI or Artificial Intelligence scenario changes, in most cases, too fast, industrial vision systems must follow suit. These involve the automated quality inspection systems of today and the autonomous robots of the future.

Whether you are an OEM or Original Equipment Manufacturer, a systems integrator, or a factory operator, trying to get the maximum performance out of a machine vision system requires future-proofing your platform. This is necessary so that you can overcome the anxiety of having launched a design only months or weeks before the introduction of the next game-changing architecture or AI algorithm.

Traditionally, the industrial machine vision system is made up of an optical sensor like a camera, lighting for illuminating the area to be captured, a controller or a host PC, and a frame grabber. In this chain, the frame grabber is of particular interest. This device captures still images at a higher resolution than the camera can. High-resolution images simplify the analysis, whether by computer vision algorithms or by AI or artificial intelligence.

The optical sensor or camera connects directly to the frame grabber over specific interfaces. The frame grabber is typically a slot card plugged into the vision platform or PC. It communicates with the host over a PCI Express bus.

Apart from its ability to capture high-resolution images, the frame grabber also has the ability to trigger and synchronize multiple cameras simultaneously. It can also perform local image processing, including color corrections, as soon as it has captured a still shot. While eliminating latency, it also eliminates the cost of transmitting images to the cloud for preprocessing, while freeing the host processor for running inferencing algorithms, executing corresponding control functions, and other tasks like turning off lights and conveyor belts.

Although the above architecture makes the arrangement more complex than some newer types that integrate various subsystems in the chain, it is much more scalable. It also provides a higher degree of flexibility, as the amount of image-processing performance achieved is limited only by the number of slots available in the host PC.

However, machine vision systems relying on high-resolution image sensors and multiple cameras can face a problem with system bandwidth. For instance, a 4MP camera needs a throughput of about 24 Mbps. PCIe 3.0 interconnects offer roughly 1 Gbps per lane data rate.

On the other hand, Gen4 PCIe interfaces double this bandwidth to almost 2 Gbps per lane. Therefore, you can connect twice as many video channels on your platform without making any other sacrifices.

However, multiple camera systems ingesting multiple streams can consume bandwidth rather quickly. Suppose you are adding one or more FPGA acceleration or GPU cards for higher accuracy, and low latency AI or executing computer vision algorithms. In that case, you have a potential bandwidth bottleneck on your hands.

Therefore, many industrial machine vision integrators make tradeoffs. They may add more host CPU to accommodate the shortage of bandwidth, use a backplane-based system to make the accelerating cards play a bigger role, or change over to a host PC with integrated accelerators. Regardless, the arrangement adds significant cost and increases power consumption and thermal dissipation. Modularizing your system architecture can safeguard against this.