Monthly Archives: April 2024

Is Metal Better than Ferrite for Inductors?

Many power and signal conditioning applications use power inductors as a basic component to store, block, filter, or attenuate energy. Today’s power circuits use increasingly higher switching frequencies and high powers that impose challenges in packaging and material levels for component manufacturers. Consequently, power inductors, while shrinking their form factors, are pushing to provide higher-rated currents.

The above presents a dual challenge to component manufacturers and designers alike. For instance, component designers must use materials other than the traditional ferrite core materials to miniaturize these devices, while maintaining other parameters such as DCR and inductance without change. Taiyo Yuden is meeting the dynamic challenges of these applications by using metal for power inductors.

Engineers typically select power inductors primarily by their inductance value, then by their current rating and DCR or DC resistance value, followed by their operating temperature range. They may also consider whether the inductor will require to have shielding or none. The application circuit that will use the inductor requires optimization of the above parameters.

Applications of power inductors can range from filtering EMI at the AC inputs of a power supply to filtering ripples at the output of a DC power supply. Inductors are indispensable for reducing the ripple in voltage and current in switching power supply outputs. DC-DC converters use inductors for their self-inductance property of storing power—as the switching circuit turns off, the inductor discharges its stored current. Almost all types of voltage regulation circuits, for instance, power supplies, DC-DC converters, switching circuits, and others, take advantage of the characteristics of power inductors.

Semiconductor power supplies are transitioning from the higher 3.3 V rails and lower currents to lower voltages of 1-1.2 V rails and higher currents for catering to advances in chip design technology. This entails the need for a high-current handling power inductor. Furthermore, smaller form factors of enclosures following the development of smaller-sized electronic components are increasing the demand for miniaturization of all associated electronic components, including the power inductor.

However, the size of power inductors and their higher current capability present a tradeoff. Withstanding higher currents typically requires a bigger case size, resulting in a change in land patterns on PCBs. On the other hand, a small size translates into saturation current due to insufficient inductance. Taiyo Yuden uses the patented construction of a wire-wound multilayer power inductor with a unique metal alloy. This construction allows the designer to achieve both the required inductance in a small case size and a high saturation current.

Taiyo Yuden create their multilayer inductor by printing a pattern on a ceramic sheet that contains ferrite. They laminate these sheets before firing them. Then they assemble the final piece, pressure bond them and fire them. At the last stage, they form external electrodes at both ends. The use of material with a high magnetic permeability results in an inductor with a high inductance value.

The construction of wire-wound inductors follows the traditional method. The coil is either on the inside or on the outside surface of a magnetic material, such as ferrite. A high number of turns results in a higher inductance and a higher DC resistance.

What are Cold-Cathode Devices?

Some devices, like thermionic valves, contain a cathode that requires heating up before the device can work. However, other devices do not require a hot cathode to function. These devices have two electrodes within a sealed glass envelope that contains a low-pressure gas like neon. With a sufficiently high voltage applied to the electrodes, the gas ionizes, producing a glow around the negative electrode, also known as the cathode. Depending on the gas in the tube, the cathode glow can be orange (for neon), or another color. Since these devices do not require a hot cathode, they are known as cold-cathode devices. Based on this effect, scientists have developed a multitude of devices.

The simplest of cold-cathode devices is the neon lamp. Before the advent of LEDs, neon lamps were the go-to lights. Neon lamps ionize at around 90 V, which is the strike voltage or breakdown voltage of the neon gas within the lamp. Once ionized, the gas will continue to glow at a voltage of around 65 V, which is its maintain or sustain voltage. This difference between the strike voltage and the sustain voltage implies the gas has a negative resistance region in the operating curve of the device. Hence, users often build a relaxation oscillator with a neon lamp, a capacitor, and a resistor.

Another everyday use for the neon lamp is as a power indicator for the AC mains. In practice, as an AC power indicator, the neon lamp requires a series resistance of around 220k – 1M ohms to limit the current flow through it, which also extends its life significantly. Since the electrodes in a neon lamp are symmetrical, using it in an AC circuit causes both electrodes to glow equally.

Neon signs, such as those in Times Square and Piccadilly Circus, also use the same effect. Instead of a short tube like in the neon lamp, neon signs use a long tube shaped in the specific design of the application. Depending on the display color, the tube may contain neon or another gas, together with a small amount of mercury. By applying a fluorescent phosphor coating to the inside of the glass tube, it is possible to produce still more colors. Due to the significant separation between the two electrodes in neon signs, they require a high strike voltage of around 30kV.

Another application of cold-cathode devices is the popular Nixie tube. Although seven-segment LED displays have now largely replaced them, Nixie tubes are still popular due to their effect as a glorified neon tube. Typically, they have ten electrodes, each in the shape of a numeral. In use, the circuit switches to the electrode required for displaying a particular number. The Nixie tube produces very natural-looking displays, hence, people find them beautiful and preferable to the stick-like seven-segment LED displays.

Photographers still use flash tubes to illuminate the scenes they are capturing. They typically use them as camera flashes and strobes. Flash tubes use xenon gas as their filling. Apart from the two regular main electrodes, flash tubes have a smaller trigger electrode near one or both the main electrodes. In use, the main electrodes have a few hundred volts between them. For triggering, the circuit applies a high-voltage pulse to the trigger electrode. This causes the gas between the two electrodes to ionize rapidly, giving off a bright white flash.

Sensors at the Heart of IoT

IoT, or the Internet of Things, depends on sensors. So much so, there would not be any IoT, IIoT, or for that matter, any type of Industry 4.0, at all, without sensors. As the same factors apply to all the three, we will use IoT as a simplification. However, some basic definitions first.

As a simple, general definition, IoT involves devices intercommunicating with useful information. As their names suggest, for IIoT and Industry 4.0, these devices are mainly located in factories. While IIoT is a network of interconnected devices and machines on a plant floor, Industry 4.0 goes a step further. Apart from incorporating IIoT, Industry 4.0 expands on the network, including higher level systems as well. This allows Industry 4.0 to process and analyze data from IIoT, while using it for a wider array of functions, including looping it back into the network for control.

However, the entire network has sensors as its basis, supplying it with the necessary raw data. Typically, the output from sensors is in the form of electrical analog signals, and IoT creates the fundamental distinction between data and information.

This distinction is easier to explain with an example. For instance, a temperature sensor, say, a thermistor, shows electrical resistance that varies with temperature. However, that resistance is in the form of raw data, in ohms. It has no meaning to us, until we are able to correlate it to degrees.

Typically, we measure the resistance with a bridge circuit, effectively converting the resistance to voltage. Next, we apply the derived voltage to a measuring equipment that we have calibrated to show voltage as degrees. This way, we have effectively converted data into information useful to us, humans. However, we can still use the derived voltage to control an electric heater or inform a predictive maintenance system of the temperature of a motor.

But information, once we have derived it from raw data, has almost endless uses. This is the realm of IoT, intercommunicating useful information among devices.

To be useful for IoT, we must convert the analog data from a sensor to a digital form. Typically, the electronics required for doing this is the ADC or Analog to Digital Converter. With IoT applications growing rapidly, users are also speeding up their networks, thereby handling even larger amounts of data, making them more power efficient.

Scientists have evolved a new method for handling large amounts of data that does not require the IoT devices to have large amounts of memory. The devices send their data over the internet to external data centers, the cloud. There, other computers handle the proper storing and analysis of the data. However, this requires higher bandwidth and involves latency.

This is where the smart sensor makes its entry. Smart sensors share the workload. A sensor is deemed smart when it is embedded within a package that has electronics for preprocessing, such as for signal conditioning, analog to digital conversion, and wireless transmission of the data. Lately, smart sensors are also incorporating AI or Artificial Intelligence capabilities.

What is Industrial Ethernet?

Earlier, we had a paradigm shift in the industry related to manufacturing. This was Industry 3.0, and, based on information technology, it boosted automation, enhanced productivity, improved precision, and allowed higher flexibility. Today, we are at the foothills of Industry 4.0, with ML or machine language, M2M or machine-to-machine communication, and smart technology like AI or artificial intelligence. There is a major difference between the two. While Industry 3.0 offered information to humans, allowing them to make better decisions, Industry 4.0 offers digital information to optimize processes, mostly without human intervention.

With Industry 4.0, it is possible to link the design office directly to the manufacturing floor. For instance, using M2M communications, CAD, or computer aided design can communicate directly to machine tools, thereby programming them to make the necessary parts. Similarly, machine tools can also provide feedback to CAD, sending information about challenges in the production process, such that CAD can modify them suitably for easier fabrication.

Manufacturers use the Industrial Internet or IIoT, the Industrial Internet of Things, to build their Industry 4.0 solutions. The network has an important role like forming feedback loops. This allows sensors to monitor processes in real-time, and the data thus collected can effectively control and enhance the operation of the machine.

However, it is not simple to implement IIoT. One of the biggest challenges is the cost of investment. But this investment can be justified through better design and manufacturing processes leading to cost savings through increased productivity and fewer product failures. In fact, reducing capital outflows is one way to accelerate adoption of Industry 4.0. Another way could be to use a relatively inexpensive but proven and accessible communication technology, like the Ethernet.

Ethernet is one of the wired networking options that is in wide use all over the world. It has good IP interoperability and huge vendor support. Moreover, POE or power over internet uses the same set of cables for carrying data as well as power to connected cameras, actuators, and sensors.

Industrial Ethernet, using rugged cables and connectors, builds on the consumer version of the Ethernet, thereby bringing a mature and proven technology to industrial automation. With the implementation of Industrial Ethernet, it is possible to not only transport vital information or data, but also remotely supervise machines, controllers, and PLCs on the shop floor.

Standard Ethernet protocol has high latency, mainly due to its tendency to lose packets. This makes it unsuitable for rapidly moving assembly lines that must run in synchronization. On the other hand, Industrial Ethernet hardware uses deterministic and low-latency industrial protocols, like PROFINET, Modbus TCP, and Ethernet/IP.

For Industrial Ethernet deployment, the industry uses hardened versions of the CAT 5e cable. For instance, the Gigabit Ethernet uses CAT 6 cable. For instance, the CAT 5e cable has eight wires formed into four twisted pairs. This twisting limits cross talk and signal interference, and each pair supports a duplex connection. Gigabit Ethernet, being a high-speed system, uses all four pairs for carrying data. For lower throughput, systems can use two twisted pairs, and the other two for carrying power or for conventional phone service.