Bench Talk

Today’s wireless charging is like commuting to work by bicycle: great in principle but a pain in practice. Cycling promises fitness, no gas bills and freedom from public transport schedules but the reality involves dodging cars, inhaling truck fumes and arriving in the office disheveled. Similarly, wireless charging has the potential (excuse the pun) to free consumers from the tedium of finding the correct charger from the dozens of incompatible units in the kitchen drawer and to cut through the Gordian knot of power cables lurking under the office desk. Yet wireless charging systems remain thin on the ground and compatible mobile devices are rarer still.

The century-old U.S. electricity grid is the largest interconnected machine on Earth. But this infrastructure––comprising more than 9,200 electric generating units with more than 1,000 gigawatts of generating capacity connected to nearly 300,000 miles (483,000 km) of transmission and distribution lines––is facing the largest disruption in its history as the way power is generated undergoes a revolution.

Designing power supplies for factory-automation equipment such as programmable logic controllers , transmitters, automation machinery and human machine interfaces can come with a lot of challenges. Even as processing power continues to increase, printed circuit board (PCB) area and overall equipment sizes tend to remain the same. To meet these strict space constraints, power-supply designs should be compact but also operate efficiently and quietly; heat and noise are absolutely not permissible. In addition, there are multiple industrial power-supply requirements, including a wide-input voltage range, a small solution size and the ability to operate at a high temperature range. Power-supply designers must keep component counts and costs down while providing a reliable solution that doesn’t require a lot of debugging. So starting with an integrated and robust device is a high priority.

All the hoopla about wireless charging doesn’t hold a candle to what Nikola Tesla had in mind: Providing alternating current through the ground and air and into the world’s products, eliminating transmission lines. If this sounds like fantasy, it indeed turned out to be, but the story of his scheme makes interesting reading.

Back in May 2015, Tesla released the Tesla Power Wall a 7kWh home battery. The idea being that it can be connected to the DC bus in a home and charge from renewables, mainly solar panels and wind turbines, when the production is high but the use is low. Later, they can be discharged during the evening peak times when load demand exceeds supply.

Wireless charging has been less than a spectacular success. Competing (that is, incompatible) standards, a slow reception by smartphone manufacturers, and RF-inhibiting aluminum phone housings and protective cases have resulted in a slow adoption rate by consumers. However, while the prime players have been battling each other, two companies have come up with solutions that eliminate the need for the inductive coils, magnetic resonance, charging pads, and mats that are required by other techniques. Intrigued?

I dread the beep my phone makes when it’s at the end of its charge. Not because I’m uncomfortable without my phone being on at all times, but because, of course, it always seems to die right when I need it most. I’m using my phone’s navigation to drive through some unfamiliar part of town when it’s dark and rainy and I’m almost out of gas and – beep – my phone is about to die.

The story of medical wearables is no different than the story of technology in general. Exponential growth in capability commensurate with the shrinking of size and cost of products is simply converging to a point that the costs of fielding preventative measures like wearables is a solid alternative to just waiting until something inside of us breaks and we are rushed to the emergency room. While medical wearables do offer great promise in helping us become more proactive in our healthcare, they are primarily data collection devices that may perform some rather simple data analysis. They will have to tie into a larger medical ecosystem that has yet to fully materialize.

Since processors are following Moore’s Law and batteries are not, people have to look at the other side of the equation, the load, to increase battery runtime. It can be the user’s choice, like ultra low power modes available on new smartphones. Or it can be an old process that is optimized, like migrating from Bluetooth to BLE. Optimizing old processes is possible because of power management options made available by powerful and efficient processors.

Have you ever tried to use a switch in an application and wondered whether the difference between the AC and DC rating on switches really matters? ­­There is a fallacy that any switch can be used so long as its current rating exceeds the maximum load requirements in the circuit. Who cares if it’s AC or DC, it’s only a 12VDC system right? Wrong; when it comes to switches, the differences in current-carrying capacity are dramatically different between AC and DC circuits and this is typically reflected in the switch’s AC and DC ratings.